Group items tagged

It's not quite Cyclops, the sci-fi superhero from the X-Men franchise whose eyes produce destructive blasts of light, but for the first time a laser has been created using a biological cell. The human kidney cell that was used to make the laser survived the experience. In future such "living lasers" might be created inside live animals, which could potentially allow internal tissues to be imaged in unprecedented detail. It's not the first unconventional laser. Other attempts include lasers made of Jell-O and powered by nuclear reactors (see box below). But how do you go about giving a living cell this bizarre ability? Typically, a laser consists of two mirrors on either side of a gain medium - a material whose structural properties allow it to amplify light. A source of energy such as a flash tube or electrical discharge excites the atoms in the gain medium, releasing photons. Normally, these would shoot out in random directions, as in the broad beam of a flashlight, but a laser uses mirrors on either end of the gain medium to create a directed beam. As photons bounce back and forth between the mirrors, repeatedly passing through the gain medium, they stimulate other atoms to release photons of exactly the same wavelength, phase and direction. Eventually, a concentrated single-frequency beam of light erupts through one of the mirrors as laser light.

"(PhysOrg.com) -- "Carbon nanotubes have a lot of really nice properties that make them good for photonics," Laurent Vivien tells PhysOrg.com. Ever since the discovery that carbon nanotubes have photoluminescence when encapsulated in micelle surfactant, Vivien points out, there has been interest in pursuing them for use in nanophotonics, and in microelectronics. "

Some scenarios with Lorentz Invariance Violation (LIV) motivated by quantum gravity do predict an energy dependence in the travel time of photons.

With this new experiment, the researchers have succeeded for the first time in experimentally reconstructing full trajectories which provide a description of how light particles move through the two slits and form an interference pattern. Their technique builds on a new theory of weak measurement that was developed by Yakir Aharonov's group at Tel Aviv University. Howard Wiseman of Griffith University proposed that it might be possible to measure the direction a photon (particle of light) was moving, conditioned upon where the photon is found. By combining information about the photon's direction at many different points, one could construct its entire flow pattern ie. the trajectories it takes to a screen.

Traditional methods of transmitting data, such as fibre optics or laser-based radar, require roughly 100 photons to transmit a single bit of data. Now a team led by Saikat Guha at Raytheon BBN Technologies in Cambridge, Massachusetts, say they can transmit 10 bits on a single photon - a 1000-fold improvement.

In 1967, Simon Kochen and Ernst Specker proved mathematically that even for a single quantum object, where entanglement is not possible, the values that you obtain when you measure its properties depend on the context. So the value of property A, say, depends on whether you chose to measure it with property B, or with property C. In other words, there is no reality independent of the choice of measurement. It wasn't until 2008, however, that Alexander Klyachko of Bilkent University in Ankara, Turkey, and colleagues devised a feasible test for this prediction. They calculated that if you repeatedly measured five different pairs of properties of a quantum particle that was in a superposition of three states, the results would differ for the quantum system compared with a classical system with hidden variables. That's because quantum properties are not fixed, but vary depending on the choice of measurements, which skews the statistics. "This was a very clever idea," says Anton Zeilinger of the Institute for Quantum Optics, Quantum Nanophysics and Quantum Information in Vienna, Austria. "The question was how to realise this in an experiment." Now he, Radek Lapkiewicz and colleagues have realised the idea experimentally. They used photons, each in a superposition in which they simultaneously took three paths. Then they repeated a sequence of five pairs of measurements on various properties of the photons, such as their polarisations, tens of thousands of times. A beautiful experiment They found that the resulting statistics could only be explained if the combination of properties that was tested was affecting the value of the property being measured. "There is no sense in assuming that what we do not measure about a system has [an independent] reality," Zeilinger concludes.

Swiss researchers have reportedly managed to make germanium suitable for lasers, which is important to eventually enable microprocessor components to communicate using light that is 10 times faster than electric currents, essentially becoming much faster photonic computers.

"I am a Neuroscientist working at the Centre for Integrative Neuroscience (CIN), University of Tübingen, Germany. In My Research I use a combination of 2-photon imaging, electrophysiology and computational modelling to unravel principles of synaptic and network computations in the vertebrate early visual system. Outside my regular work I am also co-founder of a not-for-profit organisation TReND in Africa, dedicated to foster Neuroscience Education and Research on the African continent. Moreover I am contributor to Open Labware, the design and building of open source laboratory equipment based on off-the-shelf electronics and simple mechanics as made possible by 3D printing"

A new process that simultaneously combines the light and heat of solar radiation to generate electricity could offer more than double the efficiency of existing solar cell technology, say the engineers who discovered it and proved that it works. The process, called 'photon enhanced thermionic emission," or PETE, could reduce the costs of solar energy production enough for it to compete with oil as an energy source.

ScienceDaily (July 11, 2011) - Researchers at Columbia Engineering School have built optical nanostructures that enable them to engineer the index of refraction and fully control light dispersion.

ScienceDaily (June 9, 2011) - On rare occasion, the light-sensing photoreceptor cells in the eye misfire and signal to the brain as if they have captured photons, when in reality they haven't. For years this phenomenon remained a mystery. Reporting in the June 10 issue of Science, neuroscientists at the Johns Hopkins University School of Medicine have discovered that a light-capturing pigment molecule in photoreceptors can be triggered by heat, as well, giving rise to these false alarms.