Optical wizardry Subatomic particles never cease to amaze physicists. Electronics is opening up the way to teleportation, while a photonics experiment takes a decisive step towards the control of complex quantum states. Lone electron travels through metal -------------------------------------------------------------------------------------------------------------------------------------------------------- Researchers in Grenoble have observed a lone electron move through a conducting material for the first time. This is quite an accomplishment, considering that electrons are indistinguishable from each other and have a clear ‘preference’ for moving collectively. To achieve this, the physicists connected two ‘quantum dots’, which are a kind of microscopic particle trap into which electrons can be placed one by one. One of the dots emits the electron, while the other recovers it 3 micrometers further. To transport the electron through the connection, the experimenters placed it on the crest of a sound wave, like a surfer on an ocean wave. This experimental feat opens up electronics to teleportation and quantum cryptography, two processes reserved until now for photons, the only microscopic particles that can be readily moved individually. Nature September 2011 A giant accelerator in miniature By accelerating electrons with plasma, a technique that makes it possible to generate electric fields 1,000 to 10,000 times stronger Silicon components in optical than with a conventional accelerator, physicists have succeeded in creating bunches of particles of equivalent intensity to that of the communication systems pulses produced by the SLAC linear accelerator at Stanford (US), The progressive integration of optics into conventional electronics is paving but over a distance 10,000 times shorter. This could eventually the way for a new era, and a host of technological challenges. To meet lead to particle accelerators that fit on a kitchen table. the requirements of future photonic/electronic circuits, it is essential to generate, modulate and detect light on silicon. With this in mind, French Nature Physics January 2011 researchers have experimented an extremely promising optical modulator that is rapid, effective and low-loss. Optical technology is considered as the most effective way of raising the bandwidth limits inherent to electronics. Optics Express March 2011 Einstein’s dream surpassed ----------------------------------------------------------------------------------------------------------- A hundred years ago, Albert Einstein dreamed of trapping a photon (the elementary particle of light) in a box for a period of one second. CNRS physicists have gone one step further by permanently maintaining a constant number of photons in a cavity. However, this is only possible if the photons in the cavity are measured continuously, so that their number can be adjusted if necessary. Yet the laws of quantum mechanics mean that any measurement of a microscopic system irremediably disturbs it, making it impossible to stabilize. To get around this, the researchers developed a subtle protocol in which each measurement merely performs a rough estimation of the number of photons in the cavity, thus only slightly disturbing the system. A regulator then restores the number of photons Artist’s impression of a world first: scientists have succeeded in maintaining a constant number of photons in a ‘photon box’. to the prescribed value. This is an important step towards the control of complex quantum states. Nature August 2011 31 2011 A year at CNRS
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