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  • Volume 19 January-March 2013

    1. THE INTERVIEW with Allard Mosk

      See-through science. <b>Allard Mosk</b> (1970) received his Ph.D. from the University of Amsterdam in 1999. Since 2002 he has been a member of the Complex Photonic Systems (COPS) group at the MESA+ Institute for Nanotechnology at the University of Twente in the Netherlands. His main fields of research are atomic quantum gases, thermodynamics, optics, and nanophotonics. His method has always been to complement experiments with deep theoretical knowledge of the phenomena involved. He enjoys enthusiastically presenting science to specialist and non-specialist audiences alike, and especially to students. With the support of the COPS group he has pioneered wavefront shaping to control light in opaque scattering media, an experimental method that many prominent groups worldwide are now following.Imaging through Scattering MediaSee-through science. <b>Allard Mosk</b> (1970) received his Ph.D. from the University of Amsterdam in 1999. Since 2002 he has been a member of the Complex Photonic Systems (COPS) group at the MESA+ Institute for Nanotechnology at the University of Twente in the Netherlands. His main fields of research are atomic quantum gases, thermodynamics, optics, and nanophotonics. His method has always been to complement experiments with deep theoretical knowledge of the phenomena involved. He enjoys enthusiastically presenting science to specialist and non-specialist audiences alike, and especially to students. With the support of the COPS group he has pioneered wavefront shaping to control light in opaque scattering media, an experimental method that many prominent groups worldwide are now following.Thanks to recent advances in Optics, looking trough turbid materials is no longer just a simple dream of few. In the following interview, Allard Mosk from the University of Twente takes us through a backstage tour of this fast emerging research field.
    2. DNA in a droplet on a super-hydrophobic surface. Artistic view of the evaporation process: the water cannot adhere to the super-hydrophobic surface, while the DNA bundles remain suspended and well tense.Close up on DNADNA in a droplet on a super-hydrophobic surface. Artistic view of the evaporation process: the water cannot adhere to the super-hydrophobic surface, while the DNA bundles remain suspended and well tense.We know quite a bit about our genetic code, the DNA. We know its composition, its structure, and also its function. However, we have not yet been able to look at the famous double-helix directly. Using some powerful microscopy techniques it is now possible to actually look at the primary windings of a DNA bundle.
    3. Optically activated medium. Many naturally occurring systems are Optically UnbalancedOptically activated medium. Many naturally occurring systems are Out-of-equilibrium phenomena can be the source of many a novel discovery. They are wondrous to work with, yet tough at the same time. And their very complexity is what makes them an interesting, albeit exacting challenge. The interaction between Brownian motion and optical forces now comes to provide us with new insights into these phenomena.
    4. A temperature portrait. The thermal (Boltzmann) distribution can be illustrated with balls distributed on a hilly landscape. The landscape provides both a lower and upper bound for the potential energy of the balls. At positive temperatures (left figure), common in everyday life, most balls lie in the valley around minimum potential energy. They barely move and therefore also possess minimum kinetic energy. States with small total energy are therefore more likely than those with large total energy -- the usual Boltzmann distribution. At infinite temperature (central figure) the balls spread evenly over low and high energies in an identical landscape. Here, all energy states are equally probable. At negative temperatures (right figure), however, most balls wander on top of the hill, at the upper limit of potential energy. Also their kinetic energy is maximal. Energy states with large total energy are occupied more than those with small total energy -- the Boltzmann distribution is inverted.Hot Science Below Absolute ZeroA temperature portrait. The thermal (Boltzmann) distribution can be illustrated with balls distributed on a hilly landscape. The landscape provides both a lower and upper bound for the potential energy of the balls. At positive temperatures (left figure), common in everyday life, most balls lie in the valley around minimum potential energy. They barely move and therefore also possess minimum kinetic energy. States with small total energy are therefore more likely than those with large total energy -- the usual Boltzmann distribution. At infinite temperature (central figure) the balls spread evenly over low and high energies in an identical landscape. Here, all energy states are equally probable. At negative temperatures (right figure), however, most balls wander on top of the hill, at the upper limit of potential energy. Also their kinetic energy is maximal. Energy states with large total energy are occupied more than those with small total energy -- the Boltzmann distribution is inverted.Ultracold atoms afford scientists incredible control over the behavior of gas particles. And near impossible physics, in the form of negative absolute temperatures, for example, ensues!
    5. Detecting the twist of light. The orbital angular momentum (OAM) of light can be detected after having been converted into surface waves, known as surface plasmons. This is the principle behind the new detector of OAM proposed by researchers at Harvard University.A New Twist to Optical DetectorsDetecting the twist of light. The orbital angular momentum (OAM) of light can be detected after having been converted into surface waves, known as surface plasmons. This is the principle behind the new detector of OAM proposed by researchers at Harvard University.A new arrival in the family of optical detectors gives a new twist to the detection of the orbital angular momentum of light. This could make classical and quantum optical communications even easier.
  • Volume 18 September-December 2012
    1. The light and the brain. The combination of the speed of light and the interconnectivity of the brain promises to deliver novel and more powerful computational devices that might soon be employed to complement the capabilities of today’s computers.Photonic BrainsThe light and the brain. The combination of the speed of light and the interconnectivity of the brain promises to deliver novel and more powerful computational devices that might soon be employed to complement the capabilities of today’s computers.Thinking at the speed of light may soon acquire new meaning — inspired by how the brain processes information, researchers present an optical system capable of recognizing spoken words.
    2. Inside the quantum wind tunnel. The individual ions (dots) behave like tiny magnet bars (spins) which can orient themselves according to their neighbors and reproduce very complex quantum phenomena.A Wind Tunnel for Quantum PhysicsInside the quantum wind tunnel. The individual ions (dots) behave like tiny magnet bars (spins) which can orient themselves according to their neighbors and reproduce very complex quantum phenomena.Simulating quantum phenomena on today’s computers can be extremely challenging. Yet, just like the wind tunnel changed the trajectory of modern aviation, new specially built quantum simulators may soon guide the design of tailor-made quantum materials.
    3. Peeking through turbid media. The top of the figure shows a sketch of the experiment: thanks to an SLM, it is possible to reconstruct the image of an object (the letter A) illuminated with standard illumination and hidden behind a turbid medium. The three images in the bottom row respectively show the direct image of the object, the image after the turbid medium where no reconstruction technique is applied, and, finally, the reconstructed image using the SLM (left to right).Outclassing SuperheroesPeeking through turbid media. The top of the figure shows a sketch of the experiment: thanks to an SLM, it is possible to reconstruct the image of an object (the letter A) illuminated with standard illumination and hidden behind a turbid medium. The three images in the bottom row respectively show the direct image of the object, the image after the turbid medium where no reconstruction technique is applied, and, finally, the reconstructed image using the SLM (left to right).Superheroes, watch out! A new rival, such as you have never come up against before, is in town. Progress is the name! And the exclusivity of your superpowers may well be at stake.
    4. Computed image of a hidden object. By carefully combining the multi-bounce image data at each point in the laser scan, Velten and colleagues were able to recover an image of the hidden object.Peeking Around CornersComputed image of a hidden object. By carefully combining the multi-bounce image data at each point in the laser scan, Velten and colleagues were able to recover an image of the hidden object.Until now cameras have only been able to see what is in front of them. Thanks to recent developments in ultra-fast imaging and computational photography, they may also soon be able to see objects out of the line of sight.
    5. The <i>reverse phi motion</i> optical illusion. Rapid changes of brightness engender a sensation that an object is moving in a direction opposite to the one in which it is actually moving. Here, when the circles change from black to white on alternate frames, they appear to be moving counterclockwise, while in reality they are actually moving clockwise, as you will notice if you focus (your attention) on one of them.Your Eyes Can WriteThe <i>reverse phi motion</i> optical illusion. Rapid changes of brightness engender a sensation that an object is moving in a direction opposite to the one in which it is actually moving. Here, when the circles change from black to white on alternate frames, they appear to be moving counterclockwise, while in reality they are actually moving clockwise, as you will notice if you focus (your attention) on one of them.Our eyes perceive our surroundings, convey emotion and, some may say, that they can even speak, loud and clear. Now, with the help of an optical illusion, our eyes can also write.
    6. How to generate random numbers. The setup toggles between two complementary fringe patterns (heads or tails). The center (white line) will coincide with a minimum or maximum of the pattern, which can be interpreted as a random 0 or 1.Quantum Randomness on a ChipHow to generate random numbers. The setup toggles between two complementary fringe patterns (heads or tails). The center (white line) will coincide with a minimum or maximum of the pattern, which can be interpreted as a random 0 or 1.Online banking, e-commerce and data protection are currently secured by pseudo-random numbers which could, eventually, one day be cracked due to the fact that they are not truly random. A new approach based on quantum optics may soon allow for safer operations by efficiently generating truly random numbers.
  • Volume 17 April-August 2012
    1. Artistic representation of an X-ray laser. X-rays interact with the electrons of the atom, which leads to the emission of another X-ray photon.Towards Better X-ray LasersArtistic representation of an X-ray laser. X-rays interact with the electrons of the atom, which leads to the emission of another X-ray photon.Red, green and blue lasers all produce extremely good-quality light and therefore play a key role in everyday life. X-ray lasers, in comparison, are still in their infancy. Building on the principles of visible-light lasers, however, it is possible to produce better X-rays.
    2. Evolution in black and white. The polarization pattern of the light reflected by a zebra’s coat looks very unattractive to bloodsucking horseflies, who are strongly polarotactic.Baffle the Bug!Evolution in black and white. The polarization pattern of the light reflected by a zebra’s coat looks very unattractive to bloodsucking horseflies, who are strongly polarotactic.Puzzled by the zebra’s appearance? Experimental data of recent research supports the idea that zebras developed their striped coat to stave off horseflies.
    3. Jumping spider and its 4 eyes. A jumping spider (<i>H. adansoni</i>) has well-developed camera-type eyes, seemingly like human eyes. This is in striking contrast to the compound eyes -- eyes made of many small and simple photoreceptors -- of other arthropods such as shrimps and insects.A Seriously Defocused SpiderJumping spider and its 4 eyes. A jumping spider (<i>H. adansoni</i>) has well-developed camera-type eyes, seemingly like human eyes. This is in striking contrast to the compound eyes -- eyes made of many small and simple photoreceptors -- of other arthropods such as shrimps and insects.A jumping spider about to pounce on its prey needs to be able to accurately measure its distance from its target in order to be able to hit it with precision. This is possible thanks to a visual approach previously unknown to exist in nature.
    4. A close look at an ancient paper. The way ancient paper absorbs light gives clues as to its chemical composition, which is key information in choosing the most effective technique to preserve and restore ancient manuscripts.Anti-aging Treatment for Ancient BooksA close look at an ancient paper. The way ancient paper absorbs light gives clues as to its chemical composition, which is key information in choosing the most effective technique to preserve and restore ancient manuscripts.Ancient manuscripts offer a fascinating glimpse into the knowledge and technology of times long gone. Alas, these cultural treasures fade over time as a result of the slow oxidation of cellulose. A combination of optical techniques and numerical studies may soon aid in their preservation and restoration.
    5. Visible image. A standard picture of a fresco painting shows the features we can see with the unaided naked eye. Detail of a fresco model, copied from Ghirlandaio, taken around 1930 by the restorer Benini.The Artistic Touch of LightVisible image. A standard picture of a fresco painting shows the features we can see with the unaided naked eye. Detail of a fresco model, copied from Ghirlandaio, taken around 1930 by the restorer Benini.Art masterpieces reveal surprising facets when we look at them through different eyes. Visible light is not always enough to disclose all of the details they hide. Use thermal radiation, however, and a good deal of their mysteries can be unveiled.
    6. How to challenge our current understanding of physics. Artistic illustration of a proposed experiment to probe quantum gravity: a laser pulse is used to measure the position of a mirror and look for possible quantum gravitational effects.Towards Reconciling Einstein and PlanckHow to challenge our current understanding of physics. Artistic illustration of a proposed experiment to probe quantum gravity: a laser pulse is used to measure the position of a mirror and look for possible quantum gravitational effects.Quantum physics and general relativity have completely changed our understanding of nature and kick-started the 20th century’s technological revolution — be that as it may, these two theories sometimes deliver contradictive results. A new proposal may finally be able to shed light on this issue.
    7. A random illumination pattern. The image shows a random intensity light pattern, or speckle pattern. A similar pattern can be generated by shining a laser through an opaque medium, such as a piece of paper or plastic.A Rather Random MicroscopeA random illumination pattern. The image shows a random intensity light pattern, or speckle pattern. A similar pattern can be generated by shining a laser through an opaque medium, such as a piece of paper or plastic.A new recipe from the microscopy world. Take a standard microscope, add a pinch of noise. Mix it all together and voilà: an image with improved resolution is served!
  • Volume 16 January-March 2012
    1. Quantum hacker’s toolkit. A toolbox small enough to fit in a suitcase is enough to counterfeit quantum measurements.QSI: Quantum Scene InvestigationQuantum hacker’s toolkit. A toolbox small enough to fit in a suitcase is enough to counterfeit quantum measurements.What do police detectives and quantum physicists have in common? They both often need to interpret evidence, and distinguish between false and real clues. After all, evidence pointing to a quantum phenomenon can be rigged, just like evidence pointing to a crime suspect can.
    2. Spot the cuttlefishes. The cuttlefish in the image (<i>Sepia officinalis</i>) show two distinct body patterns: non-camouflaged (top) and camouflaged (bottom). Can you spot them both?Hide and SeekSpot the cuttlefishes. The cuttlefish in the image (<i>Sepia officinalis</i>) show two distinct body patterns: non-camouflaged (top) and camouflaged (bottom). Can you spot them both?Every morning, on the seabed, a cuttlefish wakes up. It knows it must camouflage itself to fool its predators. Every morning, on the seabed, a predator fish wakes up. It knows it must keep its eyes peeled, if it wants to eat. The game for survival is on. Who will win?
    3. Wave-like behavior: A rafting experience. A probe pulse (arrow on the top left) fills the cavity with photons. A control laser pulse (arrow on the left) takes the system from the ground state to its first excited state. The internal state of the atom changes to the tune of the light waves of the photons in the cavity, where it is in a <i>strong coupling regime</i>: it oscillates between the first and second excited states, while emitting and reabsorbing photons. These oscillations are called <i>Rabi oscillations</i>. The photons emitted (arrow on the top right) by the cavity behave like waves.Sailing through the Waves of LightWave-like behavior: A rafting experience. A probe pulse (arrow on the top left) fills the cavity with photons. A control laser pulse (arrow on the left) takes the system from the ground state to its first excited state. The internal state of the atom changes to the tune of the light waves of the photons in the cavity, where it is in a <i>strong coupling regime</i>: it oscillates between the first and second excited states, while emitting and reabsorbing photons. These oscillations are called <i>Rabi oscillations</i>. The photons emitted (arrow on the top right) by the cavity behave like waves.The difference in the interaction between an atom and light can be as wide as that between a pleasant, relaxing canoe ride, and a whitewater rafting experience. It is now possible to switch back and forth between the two, ultraquickly, at the touch of a laser pulse.
    4. Breast cancer. The yellow mass in the illustration depicts a tumor located in a glandular tissue of the breast.Traffic Lights for ChemotherapyBreast cancer. The yellow mass in the illustration depicts a tumor located in a glandular tissue of the breast.Many cancer patients do not respond to chemotherapy and have to endure harmful side effects even when the treatment itself does not prove effective. A new technique could, as of the very first day, give the green or red light to continuing with the treatment.
    5. A cone cell. Schematic representation of a cone cell. The photosensitive part is the outer segment of the cell: the upper part where the various layers of cell membrane can be seen.Restless Cells in the Human EyeA cone cell. Schematic representation of a cone cell. The photosensitive part is the outer segment of the cell: the upper part where the various layers of cell membrane can be seen.The cone cells in the human eye make it possible for us to enjoy a world full of color. A new technique helps us understand these cells better by measuring their growth in the eyes of a living person.
    6. A cellular spy cam. The nanowire in the center channels light into a living cell. This light can excite fluorescent markers inside the cell and otherwise be reflected back into the nanowire. A detection system then allows us to capture the light and thus to gain insight into processes inside the living cell.Spying on Living CellsA cellular spy cam. The nanowire in the center channels light into a living cell. This light can excite fluorescent markers inside the cell and otherwise be reflected back into the nanowire. A detection system then allows us to capture the light and thus to gain insight into processes inside the living cell.Undercover agents have been using tiny spy cameras for decades. Now, thanks to nanotechnology, researchers can also go undercover and spy on living cells from the inside.
    7. Water and information distribution. Water and information is distributed through channels. Pipes transport water, communication channels, such as fiber-optic cables, transport information.Pipes Unclogged The Quantum Physics Way!Water and information distribution. Water and information is distributed through channels. Pipes transport water, communication channels, such as fiber-optic cables, transport information.Quantum effects are often portrayed as far more fragile than classical physics effects. However, classical physics sometimes lets us down when it comes to errorless transfer of data; when this is the case, quantum physics could come to the rescue!
    8. Shedding light in the dark. Zhengwei Pan and Feng Liu stand in a darkened room, using nothing but their recently invented ceramic discs that emit infrared light as a source of illumination. The image was taken using a digital camera with a night vision monocular. Their phosphorescent material was also mixed into the paint that was used to create the UGA logo behind them. There is no other source of illumination in the room; without the aid of a night vision device, the image would be completely dark.Glowing, Enchanted MaterialsShedding light in the dark. Zhengwei Pan and Feng Liu stand in a darkened room, using nothing but their recently invented ceramic discs that emit infrared light as a source of illumination. The image was taken using a digital camera with a night vision monocular. Their phosphorescent material was also mixed into the paint that was used to create the UGA logo behind them. There is no other source of illumination in the room; without the aid of a night vision device, the image would be completely dark.Never underestimate the magic of a glowing object. From the flare of a fire deep in the darkness of a cave, to the flashy neon illuminations in Times Square, luminescent materials have fascinated mankind for centuries. This enchantment continues with novel materials that can go on glowing for days without receiving continuous power from an energy source.
    9. Metal or Insulator? The image shows the charge density in the rock-salt structure of FeO. At room temperature and pressure this mineral is electrically insulating, but at the temperature and pressure conditions of Earth’s lower mantle it behaves like a metal.Journey to the Center of the EarthMetal or Insulator? The image shows the charge density in the rock-salt structure of FeO. At room temperature and pressure this mineral is electrically insulating, but at the temperature and pressure conditions of Earth’s lower mantle it behaves like a metal.What happens when we put an electric insulator, such as iron oxide, under pressure and temperature conditions as extreme as those of the Earth’s interior? The insulator turns into a conductor: a notion that will help us to refine our current understanding of the Earth’s magnetism.
    10. The unsteady world of a Brownian particle. For a microscopic particle, life is quite an adventure. Molecules come and go from its surface incessantly and its charge continues changing. Measuring these charging and discharging events is quite a challenge, which has now been met.Charge Goes Up, Charge Comes Down The unsteady world of a Brownian particle. For a microscopic particle, life is quite an adventure. Molecules come and go from its surface incessantly and its charge continues changing. Measuring these charging and discharging events is quite a challenge, which has now been met.What a wonderful world it is when looked at from the perspective of a microscopic particle! All at once, a whole lot of small things take on new importance – not least so, the behavior of the electric charges around the particle.
  • Volume 15 October-December 2011
    1. Blue light refracted from the sky. A consequence of modern life today is that we spend large amounts of time indoors, in spaces lit with white light. We are, however, biologically <i>programmed</i> for the outdoors.Blue Light Beats the BluesBlue light refracted from the sky. A consequence of modern life today is that we spend large amounts of time indoors, in spaces lit with white light. We are, however, biologically <i>programmed</i> for the outdoors.We all appreciate how a walk in the sun can do wonders for lifting our spirits, even though we may not know the exact scientific reasons behind the fact that sunshine helps fight the blues. Recent evidence sheds new (blue) light onto this mystery.
    2. Optical component made of organogels. A cylinder and a cone made of organogels are combined to produce this optical tower, which can be held safely in the palm of a hand, and which remains stable for months.Soft, Oily and Self-healingOptical component made of organogels. A cylinder and a cone made of organogels are combined to produce this optical tower, which can be held safely in the palm of a hand, and which remains stable for months.Optical components made of materials other than glass are very much sought after when it comes to engineering devices that are flexible, adaptable, and self-healing. Amongst an array of possible materials, organogels now take to the field.
    3. Little escape for light. Artistic conception of TrES-2, a Jupiter-sized gas giant that reflects less than one percent of the incident light and is, therefore, darker than acrylic paint or coal.Light from the Darkest PlanetLittle escape for light. Artistic conception of TrES-2, a Jupiter-sized gas giant that reflects less than one percent of the incident light and is, therefore, darker than acrylic paint or coal.The different colors reflected by carrots, green leaf salad, or even blueberries, give us clues as to their composition. Interestingly, the composition of exoplanets can also be inferred from their reflected light. But, what if a planet is far darker than we had ever thought possible?
    4. A nano rainbow. The LED device (on the left side) is made of an Indium Gallium Nitride (InGaN) nanodisk held between two Gallium Nitride (GaN) nanorods. The InGaN nanodisk is responsible for the emission of light spanning through the entire visible range, from violet to red.Roy G. Biv Goes NanoA nano rainbow. The LED device (on the left side) is made of an Indium Gallium Nitride (InGaN) nanodisk held between two Gallium Nitride (GaN) nanorods. The InGaN nanodisk is responsible for the emission of light spanning through the entire visible range, from violet to red.Roy G. Biv: Red, Orange, Yellow, Green, Blue, Indigo and Violet… the colors of the rainbow. New LED devices make them shine on the nanoscale.
    5. Optical pulling force. Solar radiation <i>pushes</i> comet tails away from the Sun. This is exactly the opposite of what can be seen in this artistic, and plainly unphysical, representation of a Sun exerting a <i>pulling</i> force on comet tails.Light’s Pull and PushOptical pulling force. Solar radiation <i>pushes</i> comet tails away from the Sun. This is exactly the opposite of what can be seen in this artistic, and plainly unphysical, representation of a Sun exerting a <i>pulling</i> force on comet tails.That light can exert forces by pushing objects has been known for a while. But would you have guessed that light can also pull towards the light source, just like the optical tractor beams in Star Trek?
    6. Artistic representation of a photon router. Top: Without a photon router, the photon pairs pass unobstructed. Bottom: With the photon router, one photon of each pulse is reflected and the other photon passes.The Photon BouncerArtistic representation of a photon router. Top: Without a photon router, the photon pairs pass unobstructed. Bottom: With the photon router, one photon of each pulse is reflected and the other photon passes.Technology based on individual photons may soon open the door to new ways of quantum computing. Controlling quantum systems, however, is extremely subtle and difficult. The most common model currently in use, as it now turns out, is simply insufficient — a slightly more complex approach is required.
    7. A patchy summer landscape. In summer, off the north coast of Alaska, the Chukchi and Beaufort Seas are a mosaic of open water, bare ice and melt ponds.A Brighter Summer under the IceA patchy summer landscape. In summer, off the north coast of Alaska, the Chukchi and Beaufort Seas are a mosaic of open water, bare ice and melt ponds.While Venice and other coastal cities around the world are slowly sinking, during the Arctic summer the waters underneath the ice become brighter and brighter. Are these two scenarios connected to the continuous thinning of Arctic ice?
    8. Constants of Nature. Constants of Nature have long fascinated scientists and philosophers alike. What is the reason behind their numerical values? The speed of light (which physicists familiarly call <i>c</i>) is 299 792 458 meters per second, the charge of the electron (<i>e</i>) is 0.000 000 000 000 000 000 160 217 656 5 coulombs, the Planck constant (<i>h</i>) is 0.000 000 000 000 000 000 000 000 000 000 000 662 606 957 Joules times seconds. Certainly, the logic behind these numbers is not what strikes us at first glance. In fact, generations of great scientists have racked their brains looking for any indications of regularity, for any signs of an underlying logic, for any evidence of a set of principles from which these numbers could have been derived. Unfortunately, all efforts have, to date, been unfruitful.The Number of LifeConstants of Nature. Constants of Nature have long fascinated scientists and philosophers alike. What is the reason behind their numerical values? The speed of light (which physicists familiarly call <i>c</i>) is 299 792 458 meters per second, the charge of the electron (<i>e</i>) is 0.000 000 000 000 000 000 160 217 656 5 coulombs, the Planck constant (<i>h</i>) is 0.000 000 000 000 000 000 000 000 000 000 000 662 606 957 Joules times seconds. Certainly, the logic behind these numbers is not what strikes us at first glance. In fact, generations of great scientists have racked their brains looking for any indications of regularity, for any signs of an underlying logic, for any evidence of a set of principles from which these numbers could have been derived. Unfortunately, all efforts have, to date, been unfruitful.1/137… give or take: the value of the fine-structure constant. Our Universe, our life and everything we know depend on this number. What would the consequences be, if this were to change?
  • Volume 14 July-September 2011
    1. Eyeball Camera. The image shows an adjustable-zoom camera that fits into a small, eyeball-shaped package.Eyeball Cameras: Beyond BiologyEyeball Camera. The image shows an adjustable-zoom camera that fits into a small, eyeball-shaped package.The flexibility of today’s commercial cameras is limited by the use of solid lenses and rigid detector chips. Biologically-inspired eyeball cameras with deformable imaging elements could soon revolutionize the way our devices capture the world.

    2. QEOD THESIS PRIZES

      The 2011 QEOD Thesis Prize winners. (top row from the left) Maiken Mikkelsen, Simon Gröblacher and Albert Schliesser. (bottom row from the left) Pavel Ginzberg, Alex Hayat and Alberto Politi.EPS QEOD Thesis Prizes: The Winners of 2011The 2011 QEOD Thesis Prize winners. (top row from the left) Maiken Mikkelsen, Simon Gröblacher and Albert Schliesser. (bottom row from the left) Pavel Ginzberg, Alex Hayat and Alberto Politi.Six promising young scientists have received the prestigious QEOD Thesis Prize, awarded by the Quantum Electronics and Optics division (QEOD) of the European Physical Society (EPS), for their fundamental and applied work in optics and photonics. The ceremony took place at the CLEO/Europe-EQEC meeting in Munich, in May2011. Congratulations!
    3. A 3D full color hologram of an apple. The image shown here is a photograph of a hologram that records the three dimensional structure of an apple and leaf in full color. This frame is part of a video that demonstrates how changing the viewer’s perspective of the hologram alters its appearance, as would happen when viewing the original object.Holography Goes Beyond 3DA 3D full color hologram of an apple. The image shown here is a photograph of a hologram that records the three dimensional structure of an apple and leaf in full color. This frame is part of a video that demonstrates how changing the viewer’s perspective of the hologram alters its appearance, as would happen when viewing the original object.3D vision devices are one of the biggest technology gimmicks of the day. Holography is an inherently three-dimensional technology that now supports full color. It could, therefore, provide the ultimate 3D experience, with images and movies appearing identical to the real world… and without the need for 3D glasses.
    4. Artistic view of a self-healing material at work. Novel materials attempt to mimic the unique ability of biological tissues to self-heal after receiving a wound. The new results show how the combination of supramolecular polymers with a light-heat conversion scheme is a particularly effective approach when it comes to making healable materials.Long Live the Polymer!Artistic view of a self-healing material at work. Novel materials attempt to mimic the unique ability of biological tissues to self-heal after receiving a wound. The new results show how the combination of supramolecular polymers with a light-heat conversion scheme is a particularly effective approach when it comes to making healable materials.A new class of polymer that self-heals when exposed to ultraviolet light has been developed. Could this be the dawn of a technological future with self-healing materials?
    5. A lasing cell. Certain fluorescent protein producing cells can be made to emit laser light if placed inside an appropriate optical cavity. Malte Gather and Seok Hyun Yun have obtained a green laser by placing a GFP-producing mammalian cell between two highly reflective Bragg mirrors.Bionic LasersA lasing cell. Certain fluorescent protein producing cells can be made to emit laser light if placed inside an appropriate optical cavity. Malte Gather and Seok Hyun Yun have obtained a green laser by placing a GFP-producing mammalian cell between two highly reflective Bragg mirrors.In the dawn of the third Millennium, lasers are fast becoming man’s best friend. Be that as it may, the world still perceives them as cold, lifeless devices. Can that image be shaken off, or even turned around? Can lasers be perceived as something that is, on the contrary, warm and full of life?
    6. Broadband graphene polarizer. Artistic view of a graphene polarizer turning unpolarized light (left) to horizontally polarized light (right) at multiple wavelengths (colors) simultaneously.Flat Light from a Flat DiamondBroadband graphene polarizer. Artistic view of a graphene polarizer turning unpolarized light (left) to horizontally polarized light (right) at multiple wavelengths (colors) simultaneously.The possibility to polarize light in optical fibers comes to establish graphene as a likely key player in the future of optical technologies; a new application emerges for this material that rocked the scientific world due to its fascinating properties.
    7. The atomic hologram. The experimental setup developed in Japan uses electrons to excite the emission of x-rays from titanium atoms in strontium titanate (molecular formula SrTiO<sub>3</sub>). The emitted x-ray waves interfere with the waves scattered by the surrounding atoms, thus forming a hologram of the 3D atomic arrangement in the material.A Close Up on MatterThe atomic hologram. The experimental setup developed in Japan uses electrons to excite the emission of x-rays from titanium atoms in strontium titanate (molecular formula SrTiO<sub>3</sub>). The emitted x-ray waves interfere with the waves scattered by the surrounding atoms, thus forming a hologram of the 3D atomic arrangement in the material.The deeper we try to look into matter, the larger the experimental facilities seem to become. Paddling against the flow, a new technique from Japan could soon make 3D atomic images affordable by any small laboratory around the world.
  • Volume 13 April-June 2011

    1. THE VIEWPOINT by Zuleykhan Tomova

      Why organize an IONS Conference? <br /><br />Organizing and participating in an IONS conference helps students connect with their colleagues in other countries. Participants and organizers also gain valuable experience such as presentation skills, learning about research in diverse areas, starting collaborations, and finding PhD and postdoctoral positions. For the organizers it is an excellent way to learn how to build their own team and organize group work, find sponsors and create marketing plans. Organizers also establish ties between academic and industrial communities.<br /><br /> New organizers always receive advice and suggestions from previous organizers, as well as “IONS Manual” notes, consistently updated after each event by the organizing team. “Organizing a good IONS conference is challenging (something that increases with each edition!), and very similar to what the same organizers will face later in their careers when organizing conferences, meetings or events,” says Silvia Carrasco, Knowledge & Technology Transfer Director at ICFO. “To succeed in their careers, regardless of what they decide to do, students will need leadership, management, and presentation skills, entrepreneurial spirit, networking experience, etc. All chapter activities constitute an essential part of this training. Organizing or participating in IONS makes students grow.”<br /><br /> The Optical Society of America (OSA) has sponsored the <i>IONS Project</i> from the very beginning; The International Society for Optics and Photonics (SPIE) and the European Physical Society (EPS) have recently also joined the list of sponsors. The IONS ProjectWhy organize an IONS Conference? <br /><br />Organizing and participating in an IONS conference helps students connect with their colleagues in other countries. Participants and organizers also gain valuable experience such as presentation skills, learning about research in diverse areas, starting collaborations, and finding PhD and postdoctoral positions. For the organizers it is an excellent way to learn how to build their own team and organize group work, find sponsors and create marketing plans. Organizers also establish ties between academic and industrial communities.<br /><br /> New organizers always receive advice and suggestions from previous organizers, as well as “IONS Manual” notes, consistently updated after each event by the organizing team. “Organizing a good IONS conference is challenging (something that increases with each edition!), and very similar to what the same organizers will face later in their careers when organizing conferences, meetings or events,” says Silvia Carrasco, Knowledge & Technology Transfer Director at ICFO. “To succeed in their careers, regardless of what they decide to do, students will need leadership, management, and presentation skills, entrepreneurial spirit, networking experience, etc. All chapter activities constitute an essential part of this training. Organizing or participating in IONS makes students grow.”<br /><br /> The Optical Society of America (OSA) has sponsored the <i>IONS Project</i> from the very beginning; The International Society for Optics and Photonics (SPIE) and the European Physical Society (EPS) have recently also joined the list of sponsors. Over the past few years, a new network of young researchers has taken the world by storm: IONS. The International OSA Network of Students is a global network for young scientists, which enables them to connect, exchange ideas, and learn directly from the stars of science.
    2. Implementing a continuous quantum walk. Optical micrograph of the 21 coupled waveguides (center) with three input waveguides (bottom) and 21 output waveguides where the quantum walk occurs.The Random Walk towards Quantum ComputingImplementing a continuous quantum walk. Optical micrograph of the 21 coupled waveguides (center) with three input waveguides (bottom) and 21 output waveguides where the quantum walk occurs.Subtle quantum effects will be at the heart of the quantum computers of the future. Very few existing setups, however, offer the necessary stability and control to exploit such effects at the moment. As it turns out, arrays of waveguides meet this challenge, and they, therefore, serve as test beds for studying quantum computing.
    3. The extreme light-bender. The metamaterial, which shows a refractive index of more than 30, was fabricated by placing many metallic <i>I</i> shapes very close to each other onto a hosting medium with a refractive index of only 1.8.Extreme Light-BendersThe extreme light-bender. The metamaterial, which shows a refractive index of more than 30, was fabricated by placing many metallic <i>I</i> shapes very close to each other onto a hosting medium with a refractive index of only 1.8.Common materials have only limited light-bending power. A new, manmade material can bend light to the extreme thanks to the ultra-high value of its refractive index.
    4. The reaction chamber where sunlight becomes chemical energy. This picture shows the reaction chamber of the new solar collector illuminated by light coming from a solar simulator. A quartz window at the top allows both infrared and ultraviolet radiation to enter the chamber where the cerium oxide is deposited.Solar Fuel: No More Drilling!The reaction chamber where sunlight becomes chemical energy. This picture shows the reaction chamber of the new solar collector illuminated by light coming from a solar simulator. A quartz window at the top allows both infrared and ultraviolet radiation to enter the chamber where the cerium oxide is deposited.The Earth’s reserve of fossil fuels is limited, and their production and use pollute our environment. Solar collectors offer a possible solution to the increasingly pressing demands for economically and environmentally sustainable energy.
    5. Red light turns blue. In Dam and colleagues’ experiment, the red emission of a light bulb was converted into blue using a nonlinear crystal inside a laser cavity. After the conversion, the blue image was captured with high resolution using a standard CCD camera.Upconversion ReloadedRed light turns blue. In Dam and colleagues’ experiment, the red emission of a light bulb was converted into blue using a nonlinear crystal inside a laser cavity. After the conversion, the blue image was captured with high resolution using a standard CCD camera.Recent results give new life to an old, almost forgotten technique: upconversion imaging could soon make possible the wide use of light technology for infrared detection.
    6. Detecting the twist of a black hole. The light emitted near a rotating black hole acquires a characteristic orbital angular momentum, which may be detected from Earth by using an appropriate set of radio telescope arrays and data analysis techniques.Astronomical TwistersDetecting the twist of a black hole. The light emitted near a rotating black hole acquires a characteristic orbital angular momentum, which may be detected from Earth by using an appropriate set of radio telescope arrays and data analysis techniques.Black holes are enigmatic astronomical objects, which remain, as of yet, unobserved. We may, however, be in a position to trace their trail. It is possible that a rotating black hole imparts small twists to photons passing nearby, which we may be able to detect from Earth.
    7. Superfluid light. An array of parallel (horizontal) waveguides can mimic a superfluid moving through a pipe with an obstacle at the entrance (green dots, exaggerated in size). The light intensity inside the array of waveguides is shown as rainbow colors (black: no light; yellow: highest intensity). The top panel shows the superfluid motion of light, which keeps its overall shape even after it has passed the obstacle.The bottom panel shows the light moving through the array like a dissipative fluid, for which an obstacle clearly changes the shape of the flow.Superfluid PhotonsSuperfluid light. An array of parallel (horizontal) waveguides can mimic a superfluid moving through a pipe with an obstacle at the entrance (green dots, exaggerated in size). The light intensity inside the array of waveguides is shown as rainbow colors (black: no light; yellow: highest intensity). The top panel shows the superfluid motion of light, which keeps its overall shape even after it has passed the obstacle.The bottom panel shows the light moving through the array like a dissipative fluid, for which an obstacle clearly changes the shape of the flow.Superfluidity is a peculiar quantum state of matter that resembles a liquid, albeit with no viscosity. Usually, this phenomenon is studied at ultra-low temperatures using very delicate setups. However, light can also mimic superfluid behavior, a fact which could make experiments considerably more accessible.
  • Volume 12 January-March 2011

    1. THE VIEWPOINT by Iain Ross

      DI3D™ facial 3D capture system. Why We Need Young Scientists to Interact with CompaniesDI3D™ facial 3D capture system. Today we are in a world where, although necessary, neither academic excellence nor corporate muscle are sufficient to deliver an economy where innovation thrives and hence profits can be made and quality of life be maintained. It is only where there is strong interaction between companies large and small and the academic sector that innovation can flourish. There is increasing realisation by companies, governments and the universities that “open innovation” is an essential element of any progressive industrial economy. Young researchers have a significant part to play in this by embracing the challenges at the boundaries of academic and industrial research and development.
    2. A meandering nanowire. The photon detector devised by Bitauld and coworkers is a meandering superconducting nanowire with a constriction at its center. Counting Photons at the NanoscaleA meandering nanowire. The photon detector devised by Bitauld and coworkers is a meandering superconducting nanowire with a constriction at its center. Photon detection and counting is crucial, for example, for optical communications and quantum optics. Recent advances in nanotechnology allow nanoscale detection with single photon sensitivity.
    3. Twisting phase. The phase of an electron or optical vortex twists spirally around the direction of propagation of the beam. Because of this spiral movement, the light waves cancel each other out at the center of the beam, so that the optical vortex looks like a doughnut, a ring of light with a dark hole at its center.Twisted ElectronsTwisting phase. The phase of an electron or optical vortex twists spirally around the direction of propagation of the beam. Because of this spiral movement, the light waves cancel each other out at the center of the beam, so that the optical vortex looks like a doughnut, a ring of light with a dark hole at its center.Recent experiments lend a brand new twist to the tale unfolding in the field of electron microscopy. Promising electron vortices have made their appearance at the crossroads between nanotechnology and magnetism.
    4. Quantum key distribution hack. <i>Unsuccessful hack</i>: (a) Alice sends the key to Bob; Eve interferes with the communication (here represented by a change in color). Alice and Bob detect the attack. <i>Successful hack</i>: (b) Eve blinds Bob with bright pulses; (c) Alice and Bob think that the communication channel is safe.Hack Me If You CanQuantum key distribution hack. <i>Unsuccessful hack</i>: (a) Alice sends the key to Bob; Eve interferes with the communication (here represented by a change in color). Alice and Bob detect the attack. <i>Successful hack</i>: (b) Eve blinds Bob with bright pulses; (c) Alice and Bob think that the communication channel is safe.Quantum cryptography promises inherently secure communications… in theory! But what actually happens in practice? Recent studies show how weaknesses in a real system can be exploited to perform an “undetectable” quantum hack.
    5. Inside a fluorescent molecule. The molecule shown in the picture belongs to the group of porphyrins; <i>heme</i>, the red pigment in blood cells, also belongs to the same group. Ho and collaborators have demonstrated that they are able to <i>zoom in</i> on a single molecule and create a map of its fluorescence, with a resolution never achieved before, thus showing, in quite fine detail, how the molecule works inside.The Ultimate ResolutionInside a fluorescent molecule. The molecule shown in the picture belongs to the group of porphyrins; <i>heme</i>, the red pigment in blood cells, also belongs to the same group. Ho and collaborators have demonstrated that they are able to <i>zoom in</i> on a single molecule and create a map of its fluorescence, with a resolution never achieved before, thus showing, in quite fine detail, how the molecule works inside.Even the best microscopes in the world are not powerful enough to see the details of single molecules. Now, researchers have found a way to image these details, paving the way to a better understanding of molecular physics, and taking another step towards designer molecules.
    6. Mechanical automated feedback. James Watt’s famous centrifugal governor illustrates the use of an intrinsic classical feedback mechanism to stabilize a system. The heavy balls at the end of the levers are driven away from the rotational axe as the rotational speed increases. This increases the rotational energy of this device, and stabilizes the angular speed of the machine, which drives the centrifugal governor.Quantum Circuits: Fast and CoolMechanical automated feedback. James Watt’s famous centrifugal governor illustrates the use of an intrinsic classical feedback mechanism to stabilize a system. The heavy balls at the end of the levers are driven away from the rotational axe as the rotational speed increases. This increases the rotational energy of this device, and stabilizes the angular speed of the machine, which drives the centrifugal governor.In the 20th century information technologies based on microelectronics changed the world. In the 21st century nanophotonics looks very likely to become a key factor in the building of quantum information technologies.
    7. The sensor. The system at the core of LIDAR technology is a sensor called the HDL-64E, that uses 64 spinning lasers and accumulates 1.3 million points per second in order to reconstruct a virtual map of its surroundings.LIDAR in the Driver's SeatThe sensor. The system at the core of LIDAR technology is a sensor called the HDL-64E, that uses 64 spinning lasers and accumulates 1.3 million points per second in order to reconstruct a virtual map of its surroundings.New devices based on a concept similar to that of RADAR could revolutionize your daily commute. Light detection and ranging (LIDAR) technologies are providing the vision for a new generation of driverless vehicles.
    8. Anderson localized modes of light. The high intensity peaks show the random positions where the light emitted in a disordered photonic crystal waveguide becomes strongly localized. These are signatures of Anderson localization of light.Quantum Devices to Thrive on DisorderAnderson localized modes of light. The high intensity peaks show the random positions where the light emitted in a disordered photonic crystal waveguide becomes strongly localized. These are signatures of Anderson localization of light.It is usually assumed that a greater effort to perfect control and order in a device is rewarded by better results. However, imperfection and disorder could be a state of contentment when it comes to photon trapping.
    9. A Fairy Penguin. Fairy Penguins live along the coastline of Southern Australia and New Zealand. They are the world’s smallest penguins and their feather barbs have characteristic blue shades.Fairy Penguins Know BestA Fairy Penguin. Fairy Penguins live along the coastline of Southern Australia and New Zealand. They are the world’s smallest penguins and their feather barbs have characteristic blue shades.Mirror, mirror on the wall, who is the bluest of them all? The Fairy Penguin, of course! A newly discovered biophotonic structure causes the blue shades in the feathers of the penguins found along the coastline of Southern Australia and New Zealand.
  • Volume 11 October-December 2010

    1. THE VIEWPOINT by Lulu Rodriguez

      A problem demanding a solution. One of the major limiting factors in crop production in Asia is the heavy infestation of the corn borer, Ostrinia furnacalis, yielding a 30-40% reduction of productivity. This pest already limits the food production in several asiatic countries and has a significant impact on the development of the region.Why We Should All Care about Science WritingA problem demanding a solution. One of the major limiting factors in crop production in Asia is the heavy infestation of the corn borer, Ostrinia furnacalis, yielding a 30-40% reduction of productivity. This pest already limits the food production in several asiatic countries and has a significant impact on the development of the region.The mass media are considered the most available and sometimes the only source for most of the public to gain information about scientific discoveries, controversies, events, and the work of scientists. Science reporters play a crucial role in developing a public that is literate about science so that people are able to make wise choices about issues with scientific underpinnings and become active participants in defining policy options.
    2. A subnanometer ruler for fluorescence. Different super-resolution imaging techniques based on fluorescence have been successful in measuring distances between fluorescent molecules that are only a few nanometers apart. By carefully characterizing systematic errors, it is possible to increase the resolution of these techniques to less than a nanometer.Subnanometer PerfectionA subnanometer ruler for fluorescence. Different super-resolution imaging techniques based on fluorescence have been successful in measuring distances between fluorescent molecules that are only a few nanometers apart. By carefully characterizing systematic errors, it is possible to increase the resolution of these techniques to less than a nanometer.According to French philosopher Voltaire (1694-1778) the perfect is the enemy of the good, thus not exactly desirable. As recent results show, however, where scientific research is concerned this may not always hold true.
    3. An artistic view of a light syringe. Energetic laser pulses may soon become a painless means to administer drugs directly into tissues.Light SyringesAn artistic view of a light syringe. Energetic laser pulses may soon become a painless means to administer drugs directly into tissues.Scared of needles? Fear no more! A new injection technique could make the needle obsolete by replacing it with a flash of light.
    4. Laser versus dasar. The story goes that Charles H. Townes first thought of how to implement a working laser while sitting on a bench. In 1960, the laser –- light amplification by stimulated emission of radiation -- was eventually invented. As a parody, the dasar -– darkness amplification by stimulated absorption of radiation -- was also invented in Townes’s lab.Darkness Amplification by Stimulated Absorption of Radiation, No Kidding!Laser versus dasar. The story goes that Charles H. Townes first thought of how to implement a working laser while sitting on a bench. In 1960, the laser –- light amplification by stimulated emission of radiation -- was eventually invented. As a parody, the dasar -– darkness amplification by stimulated absorption of radiation -- was also invented in Townes’s lab.In the 60s, the anti-laser concept was invented alongside the laser concept. It was a joke then, but recent research shows how interesting physics does lie within this concept.
    5. Shining light on a rat’s brain. This image is representative of the experiment preformed by Johansen and colleagues, where a specific region in a live rat’s brain was illuminated with laser light via an optical fiber.Spooky LightShining light on a rat’s brain. This image is representative of the experiment preformed by Johansen and colleagues, where a specific region in a live rat’s brain was illuminated with laser light via an optical fiber.Many are afraid of darkness, but who gets spooked by light? Light has now been used to condition rats to fear, teaching us about fear memory formation.
    6. Colors of a sunset. Aerosols in the atmosphere scatter light, creating impressive colorful sceneries.Tiny Mirrors in the Sky to Fight Global WarmingColors of a sunset. Aerosols in the atmosphere scatter light, creating impressive colorful sceneries.Tiny particles in the atmosphere play a decisive role in determining the Earth’s temperature. Can nanoparticles be deployed to fight global warming?
    7. Illusion of depth in a flat image. Is the cube engraved or embossed on the screen? The brain uses the shading patterns to recreate the third dimension and therefore the illusion of depth. Whether you perceive the cube as being engraved or embossed depends on where your brain is assuming the light is coming from. In fact, with a little effort you can even train your brain to “see” either image on command.Shades of 3D VisionIllusion of depth in a flat image. Is the cube engraved or embossed on the screen? The brain uses the shading patterns to recreate the third dimension and therefore the illusion of depth. Whether you perceive the cube as being engraved or embossed depends on where your brain is assuming the light is coming from. In fact, with a little effort you can even train your brain to “see” either image on command.How does the brain recreate a 3D world from the 2D images the eyes capture? Recent evidence shows that shadows and light may be even more important than was originally thought when it comes to the recreation of a 3D world in the brain.
  • Volume 10 July-September 2010
    1. The optical trap and the speed of a Brownian particle. The focused green laser holds a Brownian particle. The scattering from the particle gives information about the instantaneous position of the particle and it is recorded 75 million times per second using a novel photodetector. The position increments tell show the researchers the instantaneous speed of the particle.Brownian SpeedcamThe optical trap and the speed of a Brownian particle. The focused green laser holds a Brownian particle. The scattering from the particle gives information about the instantaneous position of the particle and it is recorded 75 million times per second using a novel photodetector. The position increments tell show the researchers the instantaneous speed of the particle.Brownian particles, mind the speedcam! It is now possible to measure the instantaneous speed of a Brownian particle. Not only are these measurements of fundamental importance for statistical physics, they also open up new perspectives for the study of quantum systems.
    2. 3D tomography of a nanoparticle. The 3D shape of a nanoparticle can be reconstructed from many 2D SEM images of the same. Once the 3D morphology of the nanoparticle is known, its optical response can be calculated with the algorithm developed by the researchers at the National University of Córdoba.When Shape Really Matters3D tomography of a nanoparticle. The 3D shape of a nanoparticle can be reconstructed from many 2D SEM images of the same. Once the 3D morphology of the nanoparticle is known, its optical response can be calculated with the algorithm developed by the researchers at the National University of Córdoba.Particles in the nanoworld have mostly been modeled on unrealistically ideal shapes. A recent research takes advantage of a more complex and realistic model of the complex 3D shape of a nanoparticle.
    3. How does the momentum of a photon change when it interacts with matter? Does it increase or decrease? Both viewpoint are actually correct, depending on which momentum is being considered.Abraham vs. Minkowski 1-1How does the momentum of a photon change when it interacts with matter? Does it increase or decrease? Both viewpoint are actually correct, depending on which momentum is being considered.Does a photon gain or does it lose momentum when it enters a glass slab? Both may be the simple, yet ingenious answer to this centenary dilemma.
    4. Laser spectroscopy to see the proton size. A complex laser system is needed to perform the muonic hydrogen experiment. The picture shows frequency doubling optics transforming infrared to green light.Updating the Size of the Proton: Small Difference, Big ConsequenceLaser spectroscopy to see the proton size. A complex laser system is needed to perform the muonic hydrogen experiment. The picture shows frequency doubling optics transforming infrared to green light.The proton is one of the building blocks of matter and now latest studies suggest it is considerably smaller than previously measured. This is a result that may well challenge our current understanding of nature.
    5. Tumor imaging by Cerenkov Luminescence Tomography. Reconstructed Cerenkov luminescence tomography images fused with the computed tomography image of mouse. On the left, heart and bladder. On the right, cross-section revealing the presence of a tumor.Cerenkov Photons: A Cancer SearchlightTumor imaging by Cerenkov Luminescence Tomography. Reconstructed Cerenkov luminescence tomography images fused with the computed tomography image of mouse. On the left, heart and bladder. On the right, cross-section revealing the presence of a tumor.Millions of people fall victim to cancer every year. A great number of these lives could be saved if a simple, inexpensive tool for the early detection of cancer were available. Now, a new technique called Cerenkov luminescence tomography, looks likely to offer a ray of hope in that direction.
    6. Cylindrical invisibility cloak in action. 3D view of the z-component of the electric field associated with a surface plasmon at a wavelength 600nm propagating along a 50nm-high gold film and through an invisibility cloak that surrounds a metallic cylinder. The surface plasmon continues to propagate without any distortion in the field profile.Plasmons: Transform!Cylindrical invisibility cloak in action. 3D view of the z-component of the electric field associated with a surface plasmon at a wavelength 600nm propagating along a 50nm-high gold film and through an invisibility cloak that surrounds a metallic cylinder. The surface plasmon continues to propagate without any distortion in the field profile.Latest experiments demonstrate an easy way to freely transform electromagnetic waves moving on metals. This yields promise of powerful applications, ranging from computers and biomedical devices, to solar cells and cell phones.
    7. Stop-motion to see the electrons move. The ultra-high temporal resolution of 150 attoseconds enables the reconstruction of the evolution of the electron distribution of the krypton atoms right after ionization. Notice that this evolution occurs within a few femtoseconds only.Snapshots of Electrons in MotionStop-motion to see the electrons move. The ultra-high temporal resolution of 150 attoseconds enables the reconstruction of the evolution of the electron distribution of the krypton atoms right after ionization. Notice that this evolution occurs within a few femtoseconds only.Recent, groundbreaking experiments using ultrashort laser pulses have permitted the study of the motion of electrons in atoms right after ionization. This leads the way to a better understanding and control of the motion of electrons in atoms and molecules.
  • Volume 9 April-June 2010
    1. Reconstruction of a synapse. A 3D representation of the presynaptic neuron. The yellow spheres are the vesicles filled with neurotransmitter. The different types of filaments are in red and blue, the membranes of the presynaptic and postsynaptic neuron are in purple, and the synapse is in green. The postsynaptic neuron cotent is represented in dark yellow.Neurons, Freeze!Reconstruction of a synapse. A 3D representation of the presynaptic neuron. The yellow spheres are the vesicles filled with neurotransmitter. The different types of filaments are in red and blue, the membranes of the presynaptic and postsynaptic neuron are in purple, and the synapse is in green. The postsynaptic neuron cotent is represented in dark yellow.Neurons are the building block of the arguably most complex structure of the Universe: the human brain. Recent experiments show innovative ways to shock-freeze neurons while they are communicating with each other.
    2. Oil-water Illustration of spin gradient thermometry. At low temperatures, oil and water do not mix and form clearly separated phases with a tiny interface (left). At higher temperatures, the interface region is considerably larger, allowing one to deduce the temperature of the fluids (right).The Coolest ThermometerOil-water Illustration of spin gradient thermometry. At low temperatures, oil and water do not mix and form clearly separated phases with a tiny interface (left). At higher temperatures, the interface region is considerably larger, allowing one to deduce the temperature of the fluids (right).Temperature measurements are key in science and technology. Close to absolute zero, however, they are extremely difficult. A new method now allows the measuring of some of the coolest temperatures ever produced.

    3. THE VIEWPOINT by Alejandra Valencia

      LaserFest 2010. Year-long celebration of the 50<sup>th</sup> anniversary of the invention of the laser.Happy Birthday Laser!LaserFest 2010. Year-long celebration of the 50<sup>th</sup> anniversary of the invention of the laser.May 16, 1960. A day like many others, except, of course, for the fact that on this day the laser was born. A candy store owner, a photographer, and at least four American and two Russian scientists took part in the story that led to this accomplishment. This was a humble event, which could not foreshadow the future success of the newborn laser. This year the world celebrates the 50th birthday of the laser through an initiative jointly organized by various optics and photonics organizations: the LaserFest. Happy birthday laser!
    4. A random guess. Attempting to guess the random draw of the lottery is a matter of pure luck, even though, in principle, these draws can be described by deterministic laws of physics.Truly Random Results: You Can Bet on It! A random guess. Attempting to guess the random draw of the lottery is a matter of pure luck, even though, in principle, these draws can be described by deterministic laws of physics.True randomness can hardly ever be proved. However, latest experiments on quantum systems deliver truly random results — guaranteed!

    5. THE VIEWPOINT by Jean-luc Doumont

      How noise enters our communication. Claude Shannon’s communication model places the noise source exclusively on the channel [1]. In an oral presentation, however, much worse is the noise that comes from the transmitter (the speaker).Fighting the Noise in Your CommunicationHow noise enters our communication. Claude Shannon’s communication model places the noise source exclusively on the channel [1]. In an oral presentation, however, much worse is the noise that comes from the transmitter (the speaker).One of the best-known rules of telecommunication — maximize the signal-to-noise ratio — applies equally well to professional communication and can help us greatly improve our oral presentations, written documents, and graphs.
    6. Neutrophil tracks a pseudo-bacterium. A single neutrophil tracks a microbead as it mimics a slow-moving bacterium.In Pursuit of Bacteria: A Cat-and-Mouse GameNeutrophil tracks a pseudo-bacterium. A single neutrophil tracks a microbead as it mimics a slow-moving bacterium.Cells in the immune system seem to have a sixth sense for tracking down invasive bacteria. A new technique for manipulating single cells could revolutionize our understanding of their tactics and eventually lead to new strategies for mobilizing our body's defenses against disease.
    7. An x-ray view on a yeast cell. By employing lensless x-ray diffraction microscopy, this image of a group of yeast cells has been acquired with a resolution of ten nanometers -- approximately the length of 50 water molecules in a row. This is the highest resolution ever obtained with this method for biological samples. In this image the letters represent possible structures of the cell, such as vacuoles (V), mitochondria (M), and nucleus (N).Cells through X-RaysAn x-ray view on a yeast cell. By employing lensless x-ray diffraction microscopy, this image of a group of yeast cells has been acquired with a resolution of ten nanometers -- approximately the length of 50 water molecules in a row. This is the highest resolution ever obtained with this method for biological samples. In this image the letters represent possible structures of the cell, such as vacuoles (V), mitochondria (M), and nucleus (N).Thanks to their ability to see through solid objects, X-rays are one of the most powerful tools of modern medicine. They may soon enable us to see inside a single cell with a stunning resolution of ten nanometers.
  • Volume 8 January-March 2010
    1. The unit of the Bokode. A Bokode is composed of a tiny optical lens which hides a series of miniaturized 2D barcodes. Surprisingly, a camera taking an out-of-focus picture is able to create a sharp image of the Bokode.The Future of BarcodesThe unit of the Bokode. A Bokode is composed of a tiny optical lens which hides a series of miniaturized 2D barcodes. Surprisingly, a camera taking an out-of-focus picture is able to create a sharp image of the Bokode.Thanks to barcodes, computers can extract a lot of information on our everyday lives. A new technology by MIT, the Bokode, greatly enhances barcode technology, from interactive shopping to inexpensive motion capture.
    2. A photo-acoustic image. <i>In vivo</i> Multi Spectral Opto-acoustic Tomography (MSOT) image of a section of an adult zebrafish that expresses the fluorescent protein mCherry in its brain.Listen to the Light and See Deeper A photo-acoustic image. <i>In vivo</i> Multi Spectral Opto-acoustic Tomography (MSOT) image of a section of an adult zebrafish that expresses the fluorescent protein mCherry in its brain.Imaging fluorescent proteins in thick biological samples has always been a challenge. Now a new technique has harnessed the opto-acoustic effect in order to make deep tissue imaging easier for biologists.
    3. A terahertz tunable laser. In this artistic representation, the laser is the yellow wire, which is mounted on the grey support block. The electromagnetic field inside the laser reaches beyond the transversal dimensions of the wire, which makes it possible to influence the lasing frequency by moving objects close to the wire.A New Instrument for the Laser OrchestraA terahertz tunable laser. In this artistic representation, the laser is the yellow wire, which is mounted on the grey support block. The electromagnetic field inside the laser reaches beyond the transversal dimensions of the wire, which makes it possible to influence the lasing frequency by moving objects close to the wire.Laser physics and music share surprising analogies: lasers and flutes, for example, have been tuned in a very similar way until now. Recent experiments show that lasers can also be tuned in a way that does not find a counterpart in music, well not yet at least.
    4. Light. Is the speed of light changing over time? which evidence supports such hypotesis? and which could be the consequences?Is Light Slowing Down?Light. Is the speed of light changing over time? which evidence supports such hypotesis? and which could be the consequences?The speed of light is a universal constant — or is it? Some evidence seems to suggest it might actually be slowing down. Will we soon have to revise our cosmological beliefs?
    5. Dark pulse emission. Dark pulses appear as intensity dips in a continuous light emission, as opposed to bright pulses, which are intense bursts of light.The Dark Side of LasersDark pulse emission. Dark pulses appear as intensity dips in a continuous light emission, as opposed to bright pulses, which are intense bursts of light.Some scientific discoveries completely change how we look at things: it certainly was the case for Dirac’s theory on antimatter or Einstein’s theory of relativity. Now, our existing scientific ideas are set to change once more; new experiments show that laser theory should be extended to include dark pulse emission.
    6. Strains of hair. A laser removes the outer parts and creates an aerosol of the inner, clean constituents of the hair. Isotope analysis of the constituting atoms then reveals if a subject has traveled recently or not.Forensic Optics: Transforming a Hair into a Travel LogStrains of hair. A laser removes the outer parts and creates an aerosol of the inner, clean constituents of the hair. Isotope analysis of the constituting atoms then reveals if a subject has traveled recently or not.Solving crimes usually requires a lot of time and complicated investigations in order to find clear evidence. Now, it is possible to obtain information about a suspect's travel history simply by analyzing their hair.
    7. A twisted trap. An artist depiction of a nanoparticle optically trapped using a plasmonic vortex.Tiny Plasmonic WhirlpoolsA twisted trap. An artist depiction of a nanoparticle optically trapped using a plasmonic vortex.Scientists can twist light to create tiny typhoons on metal surfaces. Particles close to the light swirls can get trapped and pulled to the center of the whirlpool, like an autumn leaf is pulled to the center of a pond whirlpool.
  • Volume 7 October-December 2009
    1. Detecting surface plasmons as electrons. Schematic of the device that converts surface plasmons into an electric current. It consists of a silver nanowire along which the surface plasmons propagate, and a crossing germanium nanowire, that converts the surface plasmons to electron-hole pairs. A quantum dot can be used to launch the surface plasmons along the nanowire.Plasmon Harvesting: A Route to Plasmonic Circuitry Detecting surface plasmons as electrons. Schematic of the device that converts surface plasmons into an electric current. It consists of a silver nanowire along which the surface plasmons propagate, and a crossing germanium nanowire, that converts the surface plasmons to electron-hole pairs. A quantum dot can be used to launch the surface plasmons along the nanowire.What cannot be seen can often be felt, even in the case of physics. Invisible electromagnetic oscillations, known as surface plasmons, trapped inside a nanowire can now be detected by converting them into an electrical current.
    2. A molecular integrated circuit. An artistic representation of a fully optical circuit created on building bocks such as the single molecule optical transistor. In the black circle, a molecule is amplifying a light signal (yellow), exactly as a transistor does on electronic signals. The control over the amplification is given by a second light beam (green), which decides whatever the molecule is amplifying, attenuating or leaving the input signal unaltered.What a Molecular Transistor!A molecular integrated circuit. An artistic representation of a fully optical circuit created on building bocks such as the single molecule optical transistor. In the black circle, a molecule is amplifying a light signal (yellow), exactly as a transistor does on electronic signals. The control over the amplification is given by a second light beam (green), which decides whatever the molecule is amplifying, attenuating or leaving the input signal unaltered.How far can a single, tiny molecule go? Exceeding most people's imagination, researchers have shown that a single molecule can actually work as a transistor for photons.
    3. Pyrochlore lattice. The pyrochlore lattice is a crystalline structure formed by a network of corner-sharing tetrahedra. The magnetic moments reside on the vertices (red points) and always point towards the center of a tetrahedron. The minimum energy arrangement is the one in which two spins point into and two spins point out of each tetrahedron. The flip of a spin generates two magnetic charges that are then free to wander around the crystal independently of each other.Magnetic Break UpPyrochlore lattice. The pyrochlore lattice is a crystalline structure formed by a network of corner-sharing tetrahedra. The magnetic moments reside on the vertices (red points) and always point towards the center of a tetrahedron. The minimum energy arrangement is the one in which two spins point into and two spins point out of each tetrahedron. The flip of a spin generates two magnetic charges that are then free to wander around the crystal independently of each other.We usually think of the north and south magnetic poles as an inseparable couple. Experiments have now shown that under the appropriate conditions they can, in fact, break up.

    4. THE VIEWPOINT by Banqiu Wu & Ajay Kumar

      ASML Alpha Demo Tool. The sketch represents a developmental full-field EUVL scanner recently developed by ASML. The UV light source (based on a discharge-produced plasma DPP) is placed on the left. The generated UV light is directed by a series of Bragg mirrors to the reflective mask used to pattern the resist (on the right). The entire tool is kept in vacuum conditions to prevent the absorption of the UV light by the air.Extreme Ultraviolet Lithography: Towards the Next Generation of Integrated Circuits ASML Alpha Demo Tool. The sketch represents a developmental full-field EUVL scanner recently developed by ASML. The UV light source (based on a discharge-produced plasma DPP) is placed on the left. The generated UV light is directed by a series of Bragg mirrors to the reflective mask used to pattern the resist (on the right). The entire tool is kept in vacuum conditions to prevent the absorption of the UV light by the air.Lithography is the most challenging technology in the semiconductor industry. The most promising next generation lithography technology is extreme ultraviolet lithography (EUVL). EUVL was proposed long ago, in 1988, but its implementation has been postponed several times. Presently, most "showstoppers" are gone, but there are still several challenges that need to be addressed. The semiconductor industry is now getting ready to use EUVL in a pre-production phase, and EUVL might be implemented for 32 nm and 22 nm technological nodes. High volume manufacturing EUVL printers will be delivered to multiple end-users from 2010.
    5. How a spaser looks like. The spaser is formed by a gold core, which is surrounded by a glasslike shell filled with green dye molecule to create a sphere of 44 nanometers in diameter.The Smallest Laser EverHow a spaser looks like. The spaser is formed by a gold core, which is surrounded by a glasslike shell filled with green dye molecule to create a sphere of 44 nanometers in diameter.A year before the 50th anniversary of the invention of the laser, laser physicists present a new breakthrough: the nanolaser. It is the smallest laser ever, which makes a whole new range of applications in nanophotonics possible.
    6. The heart of the quantum computer. This is where the ions are physically stored and processed, surrounded by lasers, electronics and vacuum systems. Tiny trap segments located at the end of this bar confine and control the ions. Quantum information processing and cooling are done by shining laser beams onto the ions.The Dawn of Scalable Quantum ComputersThe heart of the quantum computer. This is where the ions are physically stored and processed, surrounded by lasers, electronics and vacuum systems. Tiny trap segments located at the end of this bar confine and control the ions. Quantum information processing and cooling are done by shining laser beams onto the ions.How close are we to the quantum computational revolution? Quantum computers promise drastic speedups for tackling the most complex mathematical problems. Nonetheless, current precursors of quantum computers cannot be scaled efficiently to reasonably sized systems. Now, researchers have realized a new setup that can be scaled more easily than ever before.
    7. A hollow-core photonic crystal fiber (PCF). Scanning electron microscope (SEM) image of the cross-section of a hollow-core PCF. Most of the light is transmitted in the hollow-core.Two Colors is Better than OneA hollow-core photonic crystal fiber (PCF). Scanning electron microscope (SEM) image of the cross-section of a hollow-core PCF. Most of the light is transmitted in the hollow-core.Standard optical fibers have revolutionized our lives. Now new perspectives can be envisioned for a new generation of photonic crystal fibers capable of transmitting two different colors at the same time.
    8. Check out my blood! <i>Ex vivo</i> stimulated emission image of microcapillaries of a mouse ear based on endogenous hemoglobin contrast (in red color), showing individual blood cells in the vessel network (inset) surrounding sebaceous glands (green overlay based on confocal reflectance).Colors Beyond the NoiseCheck out my blood! <i>Ex vivo</i> stimulated emission image of microcapillaries of a mouse ear based on endogenous hemoglobin contrast (in red color), showing individual blood cells in the vessel network (inset) surrounding sebaceous glands (green overlay based on confocal reflectance).We need eyes to see, but we need contrast to discern. A new technique for optical microscopy can now detect molecules even when their fluorescence is overwhelmed by background noise.
  • Volume 6 July-September 2009
    1. The five dimensions of optical storage. 18 different patterns recorded on the same space using three wavelengths (700 nm, 840 nm, and 980 nm) and two states of polarizations (vertical and horizontal) each.The Five Dimensions of Optical StorageThe five dimensions of optical storage. 18 different patterns recorded on the same space using three wavelengths (700 nm, 840 nm, and 980 nm) and two states of polarizations (vertical and horizontal) each.Can 300 DVDs be squeezed into a single optical disc? Ground breaking research in the field of surface plasmon physics seems to suggest so.
    2. The core of high refraction. The picture displays the core of the metamaterial with high index of refraction proposed by the researchers at Stanford University. Both high electric permittivity and magnetic permeability are needed in order to achieve a high refractive index in a metamaterial. Metallic inclusions allowing electric charge migration give a high permittivity, but usually a small permeability because of electric currents. The shape of the metallic inclusion needs to, therefore, be optimized in order to allow electric charges to move in non-loopy paths alone.Refractive Index: To the Limits and BeyondThe core of high refraction. The picture displays the core of the metamaterial with high index of refraction proposed by the researchers at Stanford University. Both high electric permittivity and magnetic permeability are needed in order to achieve a high refractive index in a metamaterial. Metallic inclusions allowing electric charge migration give a high permittivity, but usually a small permeability because of electric currents. The shape of the metallic inclusion needs to, therefore, be optimized in order to allow electric charges to move in non-loopy paths alone.Beyond what is naturally possible... metamaterials offer new unexplored opportunities to manipulate light. Researchers show the possibility to enhance the index of refraction of a material beyond natural limits.
    3. A zero mode waveguide used for real time sequencing of a DNA molecule. A single molecule of DNA bound to DNA polymerase is immobilized at the bottom of a zero mode waveguide, which is illuminated from below by laser light. The color of the emitted fluorescence indicates the present nucleotide being added to the chain.Decoding the Code of LifeA zero mode waveguide used for real time sequencing of a DNA molecule. A single molecule of DNA bound to DNA polymerase is immobilized at the bottom of a zero mode waveguide, which is illuminated from below by laser light. The color of the emitted fluorescence indicates the present nucleotide being added to the chain.Reading information stored by genes — also known as gene sequencing — is a vital task to the study of life itself. A radically new technology has set the stage for a revolution in the deciphering of DNA strands.
    4. Drawing with atoms. Quickly steering a laser on a BEC, it is possible to arrange the ultracold atoms in any shape. This technique can clear the way for new ultra-sensitive miniature sensors for atomic interactions. The Ultracold Laser ShowDrawing with atoms. Quickly steering a laser on a BEC, it is possible to arrange the ultracold atoms in any shape. This technique can clear the way for new ultra-sensitive miniature sensors for atomic interactions. In nightclubs and live concerts, figures or text are often outlined by quickly steering one single laser beam. The same principle has now been applied to drawing potentials onto ultracold gases: a new technique that could soon make its way into laboratories.
    5. A LEGO optical setup. Beam-expander system -- He-Ne laser, beam stopper, polarizer, 2 mirrors, concave lens, convex lens, screen -- built using standard LEGO components. The mount system is more compact than older ones and all optical parts are on rotating stages in order to make the adjustment of the optical axis easier. This is a well-known Galileo type beam expander (4X magnification). Inset: path of the beam.LEGO-OpticsA LEGO optical setup. Beam-expander system -- He-Ne laser, beam stopper, polarizer, 2 mirrors, concave lens, convex lens, screen -- built using standard LEGO components. The mount system is more compact than older ones and all optical parts are on rotating stages in order to make the adjustment of the optical axis easier. This is a well-known Galileo type beam expander (4X magnification). Inset: path of the beam.When I hear, I forget; when I see, I remember; but only when I do, do I understand. When it is not possible to let students play with expensive optical setups, LEGO comes into play.
    6. Negative refraction. The picture on the left shows how a spoon in a glass of water appears to break at the air-water interface, and then continues inside the liquid slightly shifted to one side, but still keeping the same orientation as in air -- left-to-right in this case. This optical illusion is due to the fact that the refractive index of water is different from the one of air -- still positive though, as in any other natural material. On the right, there is a basic illustration of what would happen by filling the glass with a liquid with a negative index of refraction: the orientation of the spoon inside the liquid would appear to be diametrically opposite to the spoon in the air, namely right-to-left instead of left-to-right.Magical MetamaterialsNegative refraction. The picture on the left shows how a spoon in a glass of water appears to break at the air-water interface, and then continues inside the liquid slightly shifted to one side, but still keeping the same orientation as in air -- left-to-right in this case. This optical illusion is due to the fact that the refractive index of water is different from the one of air -- still positive though, as in any other natural material. On the right, there is a basic illustration of what would happen by filling the glass with a liquid with a negative index of refraction: the orientation of the spoon inside the liquid would appear to be diametrically opposite to the spoon in the air, namely right-to-left instead of left-to-right.Magic lies in the beauty of a powerful illusion. This is what the latest achievements in optics seem to suggest; metamaterials are now able to optically turn one object into another.
    7. A contact lens with integrated circuitry. A researcher of the University of Washington holds a contact lens which embeds LEDs and other electrical components and which is manufactured using their newly developed self-assembly technique.Much More than a Contact LensA contact lens with integrated circuitry. A researcher of the University of Washington holds a contact lens which embeds LEDs and other electrical components and which is manufactured using their newly developed self-assembly technique.Super contact lenses which display background information onto your real world view seem like a gadget taken from the latest Spielberg movie. Thanks to a recently developed technique, this scenario may soon be real.
    8. Transparent ILED display. The transparent micro-ILED array is placed in front of the logo pattern of the University of Illinois at Urbana-Champaign (USA).A Brighter Future for LED Displays Transparent ILED display. The transparent micro-ILED array is placed in front of the logo pattern of the University of Illinois at Urbana-Champaign (USA).The displays of the future will be stretchable, twistable, deformable into any shape, and, perhaps more importantly, durable, efficient, and cheap. This is the promise of a new approach for manufacturing inorganic light emitting devices (ILEDs).
    9. A view through a METATOY. A sheet covered with tiny Dove prisms acts almost like a homogeneous surface and mimicks negative refraction in metamaterials. Here, a straight line perpendicular to the sheet appears bent into a hyperbola.From Fascination to RealityA view through a METATOY. A sheet covered with tiny Dove prisms acts almost like a homogeneous surface and mimicks negative refraction in metamaterials. Here, a straight line perpendicular to the sheet appears bent into a hyperbola.A deep fascination with the flight of birds inspired the invention of the airplane. A deep fascination with the stars inspired the invention of the telescope. What will fascination with metamaterials inspire?
  • Volume 5 April-June 2009
    1. Thermal nanoimage. By illuminating with a laser a surface where gold nanorods are unevenly placed, sharp temperature gradients can be created on microscopic scales. Here such gradients are measured on a 30x30 microns area. The temperature varies between 24º(black) and 31º (yellow). Inset: microscope image of the same area where the nanorod density can be seen.Thermal Images at the NanoscaleThermal nanoimage. By illuminating with a laser a surface where gold nanorods are unevenly placed, sharp temperature gradients can be created on microscopic scales. Here such gradients are measured on a 30x30 microns area. The temperature varies between 24º(black) and 31º (yellow). Inset: microscope image of the same area where the nanorod density can be seen.How would you measure the temperature of a nanoscopic object? How would you build a nano-thermometer? A new technique offers a solution.
    2. Looking inside the trap. The electron beam is scanned through the BEC very quickly. Since only few atoms are ionized during each run (left), this process is repeated 300 times to acquire an image of the spatial distribution of the atoms (right).Spying on Quantum GasesLooking inside the trap. The electron beam is scanned through the BEC very quickly. Since only few atoms are ionized during each run (left), this process is repeated 300 times to acquire an image of the spatial distribution of the atoms (right).A detective can only guess what mafia clans discuss inside their hideout. In a similar way, scientists usually only have indirect access to the behavior of trapped ultracold atomic gases. A novel microscopy technique now offers the possibility to directly observe what is happening inside the trap.
    3. Dynamically generated micro-channels. An arbitrary array of channels -- in this case the letters The Ice Age of MicrofluidicsDynamically generated micro-channels. An arbitrary array of channels -- in this case the letters The vision of shrinking a full lab into a chip is gradually becoming a reality. Now the possibility to dynamically generate microchannels with a laser spot in a slab of ice opens new possibilities towards a reconfigurable lab-on-a-chip.
    4. Brick by brick. Nanowalls with different shapes at the desired position built from the bottom-up, laying them down brick by brick.Another Brick in the NanowallBrick by brick. Nanowalls with different shapes at the desired position built from the bottom-up, laying them down brick by brick.Scientists, just as nano-architects would, are exploring different ways to design nanostructures with fine control over shape and position. A brand-new approach now allows one to build 2D nanowalls up by laying them down brick by brick.

    5. THE VIEWPOINT by Yaroslav Kartashov

      Possible applications of discrete solitons. Upper row: A nonlinear array network involving consecutive bends. The waveguide cross-sections are shown in green. A discrete soliton, shown in red, is set in motion in this system by appropriately tilting the beam. Computer simulations indicate that discrete soliton can successfully negotiate a sequence of bends. Lower row: An X-switching junction that uses two different discrete soliton families, signal (red) and blockers (blue). Unlike signal, which are highly mobile, blockers tend to retain their position after a collision event. After incoherent collision, the signal soliton is routed toward the lower branch, because of the presence of the two blockers at the entries of the respective pathways.Optical Lattice Solitons: Guiding and Routing Light at WillPossible applications of discrete solitons. Upper row: A nonlinear array network involving consecutive bends. The waveguide cross-sections are shown in green. A discrete soliton, shown in red, is set in motion in this system by appropriately tilting the beam. Computer simulations indicate that discrete soliton can successfully negotiate a sequence of bends. Lower row: An X-switching junction that uses two different discrete soliton families, signal (red) and blockers (blue). Unlike signal, which are highly mobile, blockers tend to retain their position after a collision event. After incoherent collision, the signal soliton is routed toward the lower branch, because of the presence of the two blockers at the entries of the respective pathways.Optical solitons are localized nonlinear excitations, which exist due to the mutual balance of diffraction and nonlinearity (in the case of spatial solitons) or dispersion and nonlinearity (in the case of temporal solitons). Moreover, they can propagate undistorted over indefinitely long distances. Being nonlinear objects, solitons may interact with each other, sometimes elastically, as if they were mechanical particles, or inelastically, when several solitons may merge together or give birth to new solitons after interaction. In the case of spatial solitons, the transverse modulation of the refractive index of the nonlinear material drastically affects their properties and affords new tools for the control of soliton propagation dynamics. Here, we review some possibilities for soliton control offered by periodic lattices and lattices produced by nondiffracting light beams.
    6. Teaming up in the right number. In rowing a given number of athletes join forces to compete. No deviation from this number could prevail during a competition. Similarly, in Efimov physics only certain numbers of bosons can bind together.Forging Quantum TeamsTeaming up in the right number. In rowing a given number of athletes join forces to compete. No deviation from this number could prevail during a competition. Similarly, in Efimov physics only certain numbers of bosons can bind together.A rowing team consists of a given number of athletes; adding or subtracting one would make it impossible for the team to compete. Recent experiments have shown that conditions exist under which quantum particles can also team up in a controlled number.
  • Volume 4 January-March 2009

    1. THE VIEWPOINT by Niek van Hulst

      STORM vs. Fluorescence Microscopy. Mitochondrial network in a mammalian cell visualized by 3D STORM. Conventional fluorescence image (left), 3D STORM image with colors denoting z location (middle) and single xy cross-section from the 3D STORM image (right).Many Photons get More out of DiffractionSTORM vs. Fluorescence Microscopy. Mitochondrial network in a mammalian cell visualized by 3D STORM. Conventional fluorescence image (left), 3D STORM image with colors denoting z location (middle) and single xy cross-section from the 3D STORM image (right).Nanoscopy, optical microscopy with 10-30 nm detail, has become a reality; in fact it has been chosen “Method of the year 2008” by Nature Methods [1]. We are all aware of the wave nature of light and the ensuing diffraction limit for resolution. So have the rules of physics been broken? What’s the trick and where’s the catch?
    2. Weak quantum questions. The researchers verified that a series of two weak quantum measuments can lead to restore the original state. The second measurement effectively undoes the effect of the first one. The picture shows the heart of the setup, where the qubits were generated and handled.Asking Twice, Yet Knowing NothingWeak quantum questions. The researchers verified that a series of two weak quantum measuments can lead to restore the original state. The second measurement effectively undoes the effect of the first one. The picture shows the heart of the setup, where the qubits were generated and handled.Have you ever been confused by an answer? Usually answers increase our knowledge, but latest experiments now show that asking two weak questions can leave us with less information than asking only one.
    3. An example of optical nanocircuit. Several nanostructures arranged next to each other at the nanoscale could become the present electronic circuits, allowing to rescale down radio-frequencies concepts such as the one of resistance (R), capacitance (C) and inductance (L).Twisting the Knob of LightAn example of optical nanocircuit. Several nanostructures arranged next to each other at the nanoscale could become the present electronic circuits, allowing to rescale down radio-frequencies concepts such as the one of resistance (R), capacitance (C) and inductance (L).Tuning nano-antennas may soon become as simple as tuning a radio to our favorite station — this is the new promise of nano-photonics.
    4. Experimental setup. A silica filament hanging in vacuum is observed while the light bends it.Pouring Oil on Troubled Light-MomentumExperimental setup. A silica filament hanging in vacuum is observed while the light bends it.What happens when light enters a medium? Does it gain or lose momentum? More than 100 years after its initial formulation, this dilemma is now being revitalized by new experiments.
    5. Over-squeezing. After a certain point, the squeezing does not improve the measurement anymore, but the opposite happens and more squeezing results in an increased uncertainty. The orange area on the surface of the sphere represents the polarization of the three-photon state. If the uncertainty for the polarization in one direction is squeezed hard, the uncertainty in the other direction wraps around the sphere.Squeezing the Most out of PhotonsOver-squeezing. After a certain point, the squeezing does not improve the measurement anymore, but the opposite happens and more squeezing results in an increased uncertainty. The orange area on the surface of the sphere represents the polarization of the three-photon state. If the uncertainty for the polarization in one direction is squeezed hard, the uncertainty in the other direction wraps around the sphere.Science relies on precise measurements. But how precise can a measurement be in principle? A new experiment shows a surprising new limit, together with a way around that limit.
    6. Nanotomography. The novel optical tomography technique allows the reconstruction of a 3D topographical map of the orientation of liquid crystal molecules by scanning a fiber tip inside the sample and collecting the polarized light transmitted by the liquid crystals.Images Worth a Thousand... Birefringent MoleculesNanotomography. The novel optical tomography technique allows the reconstruction of a 3D topographical map of the orientation of liquid crystal molecules by scanning a fiber tip inside the sample and collecting the polarized light transmitted by the liquid crystals.An image is worth a thousand words when describing complex physical phenomena such as temperature distributions, air flows and brain waves; a recently developed technique can now help us actually picture birefringent fluids at the nanoscale.
  • Volume 3 October-December 2008
    1. A quantum dot in an optical trap. A single quantum dot can be trapped and manipulated by an optical tweezers.A Nano-Firefly in the TrapA quantum dot in an optical trap. A single quantum dot can be trapped and manipulated by an optical tweezers.Fireflies emit pulses of light that allow them to be localized. Quantum dots behave in the same way albeit at the nanoscale. Now they can be manipulated using a relatively low power optical trap.
    2. Schematic of a UV laser diode. This schematic shows the 3D structure of the new laser diode by Hamamatsu Photonics. The dark blue layer is the active material which lases at 342 nanometers thanks to the absence of indium.An Ultraviolet Laser DiodeSchematic of a UV laser diode. This schematic shows the 3D structure of the new laser diode by Hamamatsu Photonics. The dark blue layer is the active material which lases at 342 nanometers thanks to the absence of indium.Laser diodes are the cheapest and most reliable lasers; nevertheless, they have hardly been able to emit in UV until now. This last barrier has now been broken, thus enabling potential and important applications, ranging from medicine to security issues.
    3. Generation of a pure sigle photon. The laser pulse (blue) enters a non-linear crystal that generates two photons (red, middle). A polarizing beam splitter is then used to separate the two photons of which one is used as a trigger (left) to indicate that there is another photon (right) ready to be used. Make Two, Keep OneGeneration of a pure sigle photon. The laser pulse (blue) enters a non-linear crystal that generates two photons (red, middle). A polarizing beam splitter is then used to separate the two photons of which one is used as a trigger (left) to indicate that there is another photon (right) ready to be used. To generate single photons remains a challenge, to have them in a pure, well-defined quantum state even more so. Now this is possible, thus paving the way for future quantum technologies and applications.
    4. The size of a US quarter. An exemplar of the new microscope developed at Caltech. In the picture, the comparison between the microscope and a US quarter can be seen.Honey, I Shrunk the Microscope!The size of a US quarter. An exemplar of the new microscope developed at Caltech. In the picture, the comparison between the microscope and a US quarter can be seen.Many of the everyday objects that we use are small enough to fit in our pockets. Take cell phones, with all their different accessories, for instance: are they also likely to come equipped with microscopes the size of a US quarter one day?
    5. Nerve Regeneration on a chip. An artist’s impression of a <i>C. elegans</i> worm immobilized in the microfluidic chamber, subjected to the process of nano-neurosurgery.Neurosurgery goes Nano inside a ChipNerve Regeneration on a chip. An artist’s impression of a <i>C. elegans</i> worm immobilized in the microfluidic chamber, subjected to the process of nano-neurosurgery.One of the standing goals of neuroscience is to understand neurons at a cellular level, in vivo. A recent development takes this goal one step further by enabling axon cuts and the study of nerve regeneration on individual neurons in live organisms.
    6. A knotted light beam. The complex structure of the lines of the electric field and of the magnetic field can be appreciated.Light's Ring-around-the-roseyA knotted light beam. The complex structure of the lines of the electric field and of the magnetic field can be appreciated.Can light travel only in straight lines? A new kind of light beam that travels along circles may soon provide an interesting twist to this question.
    7. Entangled coins. If two entangled coins were flipped, they would land on correlated sides: for example, whenever one landed on heads, the other one would land on tails. This kind of correlation is at the heart of quantum mechanics and cannot usually be seen in macroscopic objects. Now, Hartmann and Plenio have proposed a way to observe this correlation in membranes the size of a pinhead and, therefore, considerably larger than the atoms or photons that are mostly used in entanglement experiments.Visible and EntangledEntangled coins. If two entangled coins were flipped, they would land on correlated sides: for example, whenever one landed on heads, the other one would land on tails. This kind of correlation is at the heart of quantum mechanics and cannot usually be seen in macroscopic objects. Now, Hartmann and Plenio have proposed a way to observe this correlation in membranes the size of a pinhead and, therefore, considerably larger than the atoms or photons that are mostly used in entanglement experiments.Until recently, quantum behavior seemed to be the exclusive domain of tiny objects like atoms or electrons. However, entanglement of millimeter-sized membranes may soon come about, thus bringing quantum physics closer to our macroscopic world.
    8. Spooky action at a distance. How can two photons be correlated over a distance? If the photons communicated with each other, they would have to do so at an unbelievable speed, maybe instantaneously, researchers from Geneva conclude.The Spooky Physics of EntanglementSpooky action at a distance. How can two photons be correlated over a distance? If the photons communicated with each other, they would have to do so at an unbelievable speed, maybe instantaneously, researchers from Geneva conclude.In quantum physics, seemingly instantaneous correlations between distant objects can exist. Do these objects communicate? Probably not. However, if they do, their communication must be faster than the speed of light.
  • Volume 2 August-September 2008
    1. Schematic of a polymer blend. Microdroplets of a polymer are embedded in a matrix of a different polymer. Sometimes they escape.The Runaway PolymerSchematic of a polymer blend. Microdroplets of a polymer are embedded in a matrix of a different polymer. Sometimes they escape.Polymer blends are allies in our everyday lives, but they can also become our worst enemies, if the polymers mix too much. It is now possible to track down the polymers' behavior at the micrometer scale.
    2. Contracting heart cell. The image sequence shows the actual contraction of a cardiomyocyte, after it has been exposed to a series of femtosecond laser pulses.Cells in the Heart Dance to the Tune of LightContracting heart cell. The image sequence shows the actual contraction of a cardiomyocyte, after it has been exposed to a series of femtosecond laser pulses.The rhythmic beat of the heart keeps us alive. This beat is the result of an electrical mechanism, ingeniously put in place by nature, to control its cells. Surprisingly, ultrashort light pulses can do the same, virtually making these cells dance to the tune of light.
    3. Integrated flashes of light. A simple circuit, where three exciton-based transistors (EXOTs) have been integrated to perform some basic computation. Every EXOT, when processing signals, emits flashes of light as shown in the picture.Will Excitonic Circuits Change Our Lives?Integrated flashes of light. A simple circuit, where three exciton-based transistors (EXOTs) have been integrated to perform some basic computation. Every EXOT, when processing signals, emits flashes of light as shown in the picture.Transistors that process signals by emitting flashes of light: is this the milestone of a technological revolution in computation? Whether this scenario is science or fiction, only the future will tell.
    4. Measured cloud distribution of the earth. From outer space, clouds appear brighter than land and oceans because they reflect more light. Since the clouds are unevenly distributed in an earth-like planet, fluctuations in its brightness are expected.Checking the Weather of Alien PlanetsMeasured cloud distribution of the earth. From outer space, clouds appear brighter than land and oceans because they reflect more light. Since the clouds are unevenly distributed in an earth-like planet, fluctuations in its brightness are expected.Which planets in the universe are habitable? Check the weather! It is now possible to know if extra-solar planets have earth-like weather by analyzing the signature the weather leaves in the light scattered by these planets.
    5. The polymeric hummingbird’s wing. A polymeric cantilever containing photosensitive molecules (azobenzene, shown in the picture) starts to oscillate rapidly when exposed to light radiation. Just like the oscillations of a hummingbird’s wing, these oscillations occur at about thirty cycles per second (30 Hz).The Polymer and the Hummingbird’s WingThe polymeric hummingbird’s wing. A polymeric cantilever containing photosensitive molecules (azobenzene, shown in the picture) starts to oscillate rapidly when exposed to light radiation. Just like the oscillations of a hummingbird’s wing, these oscillations occur at about thirty cycles per second (30 Hz).Hummingbirds are unique and amazing birds: they can hover mid-air by rapidly flapping their wings. Even more amazing is the fact that an artificial polymer, which oscillates when exposed to laser light, can flutter like a hummingbird’s wing.
    6. The galloping race horse. By taking pictures of a process at different times and recombining the images, one can get a better understanding of a dynamical process. This picture, for example, proved that a race horse does take all feet off the ground while galloping. High-speed laser pulses can be used to image fast processes like electrons orbiting in molecules at different times.Towards Filming Chemical ReactionsThe galloping race horse. By taking pictures of a process at different times and recombining the images, one can get a better understanding of a dynamical process. This picture, for example, proved that a race horse does take all feet off the ground while galloping. High-speed laser pulses can be used to image fast processes like electrons orbiting in molecules at different times.High-speed cameras can film a bullet passing through an apple. Chemical reactions, however, are far too fast even for the best cameras. Attosecond physics promises new approaches to study and manipulate them.
  • Volume 1 June-July 2008
    1. Localized by disorder. Images of temporal evolution of the Bose-Einstein Condensate (BEC). Without disorder (top) the BEC expands freely in the non-confined direction, shown as vertical. With disorder (bottom) the BEC stays localized.The Disordered Quantum PrisonLocalized by disorder. Images of temporal evolution of the Bose-Einstein Condensate (BEC). Without disorder (top) the BEC expands freely in the non-confined direction, shown as vertical. With disorder (bottom) the BEC stays localized.Imagine a prison without walls, an open field where prisoners cannot leave simply because the field is not smooth. This is the idea behind Anderson Localization and has recently been observed in ultracold atomic gases.
    2. The plasmonic Ariadne's thread. Example of time signal generated by a plasmonic nanostructure following an external excitation. These signals reverted in time can be used to control light localization in the same nanostructure.Rewinding Plasmons Back in TimeThe plasmonic Ariadne's thread. Example of time signal generated by a plasmonic nanostructure following an external excitation. These signals reverted in time can be used to control light localization in the same nanostructure.Day-to-day life common sense often does not apply in science. But sometimes it works better than any other approach. Scouts know that retracing back clear markers on the way can avoid getting lost, the same principle has been recently proved to work in nanoplasmonics.
    3. Mantis shrimp (Gonodactylus smithii). Each of its eyes measures the six polarisation components that are precisely required.Super-Vision for Mr. ShrimpMantis shrimp (Gonodactylus smithii). Each of its eyes measures the six polarisation components that are precisely required.There is an invisible world illuminated by polarized light. A world that has been disclosed to us only by the technological advances of the last decades. Surprisingly, various Australian shrimps can see it.
    4. Microscope versus nanoscope. Diffraction-limited 3D focal spot in standard optical microscopy (<i>top</i>) compared to the 45 nm spherical one now achieved in optical nanoscopy (<i>bottom</i>).Nanoscopy: Shedding Light on LifeMicroscope versus nanoscope. Diffraction-limited 3D focal spot in standard optical microscopy (<i>top</i>) compared to the 45 nm spherical one now achieved in optical nanoscopy (<i>bottom</i>).Where traditional optical microscopy fails, a new tool, the nanoscope, overcomes the last barrier: the diffraction limit. It can explore the interior of cells in 3D, non-invasively, and with nanometric resolution.
    5. The heart of the optical clock. This part of the size of a fingernail contains the ion trap. Optical transitions of trapped aluminum and mercury ions serve as a reference, making measurements possible that are more accurate than ever before.Time to Test PhysicsThe heart of the optical clock. This part of the size of a fingernail contains the ion trap. Optical transitions of trapped aluminum and mercury ions serve as a reference, making measurements possible that are more accurate than ever before.How can we be sure about anything in nature? Without experiments, all physics is merely speculation. Optical clocks now allow us to test science with unprecedented accuracy, refining our understanding of the universe.
    6. A single-molecule fingerprint. TERS image of a single molecule about 10 nm wide.The Single Molecule Raman DetectivesA single-molecule fingerprint. TERS image of a single molecule about 10 nm wide.Who would you hire to localize a single molecule? A new detective is now available! A nano-lightning rod can do the job. It can act as a single-molecule fingerprint detective with an unprecedented spatial resolution up to 15 nanometers.
    7. A random laser flash of light. A random laser (red) shines light in all direction while it is pumped by a standard unidirectional laser (yellow).Random Lasers under ControlA random laser flash of light. A random laser (red) shines light in all direction while it is pumped by a standard unidirectional laser (yellow).Random lasers are generally difficult to control: they emit in every direction at once and in many different colors. Now, exploiting a fundamental physical phenomenon, it is possible to choose their color.
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