New method for solar cells.
New solar cells could lead to improved light-emitting diodes, lasers and sensors.
Mercouri G. Kanatzidis.
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“Nothing is impossible!” In line with this motto, physicists from the Quantum Dynamics Division of Professor Gerhard Rempe (director at the Max Planck Institute of Quantum Optics) managed to realise a quantum logic gate in which two light quanta are the main actors. The difficulty of such an endeavour is that photons usually do not interact at all but pass each other undisturbed. This makes them ideal for the transmission of quantum information, but less suited for its processing. The scientists overcame this steep hurdle by bringing an ancillary third particle into play: a single atom trapped inside an optical resonator that takes on the role of a mediator. “The distinct feature of our gate implementation is that the interaction between the photons is deterministic”, explains Dr. Stephan Ritter. “This is essential for future, more complex applications like scalable quantum computers or global quantum networks.”
In all modern computers, data processing is based on information being binary-coded and then processed using logical operations. This is done using so-called logic gates which assign predefined output values to each input via deterministic protocols. Likewise, for the information processing in quantum computers, quantum logic gates are the key elements. To realise a universal quantum computer, it is necessary that every input quantum bit can cause a maximal change of the other quantum bits. The practical difficulty lies in the special nature of quantum information: in contrast to classical bits, it cannot be copied. Therefore, classical methods for error correction cannot be applied, and the gate must function for every single photon that carries information.
Because of the special importance of photons as information carriers – for example, for communicating quantum information in extended quantum networks – the realisation of a deterministic photon-photon gate has been a long-standing goal. One of several possibilities to encode photonic quantum bits is the use of polarisation states of single photons. Then the states “0” and “1” of a classical bit correspond to two orthogonal polarisation states. In the two-photon gate, the polarisation of each photon can influence the polarisation of the other photon. As in the classical logic gate it is specified beforehand which input polarisation leads to which output polarisation. For example, a linear polarisation of the second photon is rotated by 90° if the first one is in the logic state “1”, and remains unchanged if the first one is in “0”.
Nearly 1,000 times thinner than a human hair, nanowires can only be understood with quantum mechanics. Using quantum models, physicists from Michigan Technological University have figured out what drives the efficiency of a silicon-germanium (Si-Ge) core-shell nanowire transistor.
Core-Shell Nanowires
The study, published last week in Nano Letters, focuses on the quantum tunneling in a core-shell nanowire structure. Ranjit Pati, a professor of physics at Michigan Tech, led the work along with his graduate students Kamal Dhungana and Meghnath Jaishi.
Continue reading “Probing Quantum Phenomena in Tiny Transistors” »
Bowtie-shaped nanoparticles made of silver may help bring the dream of quantum computing and quantum information processing closer to reality. These nanostructures, created at the Weizmann Institute of Science and described recently in Nature Communications, greatly simplify the experimental conditions for studying quantum phenomena and may one day be developed into crucial components of quantum devices.
The research team led by Prof. Gilad Haran of Weizmann’s Chemical Physics Department — postdoctoral fellow Dr. Kotni Santhosh, Dr. Ora Bitton of Chemical Research Support and Prof. Lev Chuntonov of the Technion-Israel Institute of Technology — manufactured two-dimensional bowtie-shaped silver nanoparticles with a minuscule gap of about 20 nanometers (billionths of a meter) in the center. The researchers then dipped the “bowties” in a solution containing quantum dots, tiny semiconductor particles that can absorb and emit light, each measuring six to eight nanometers across. In the course of the dipping, some of the quantum dots became trapped in the bowtie gaps.
Under exposure to light, the trapped dots became “coupled” with the bowties — a scientific term referring to the formation of a mixed state, in which a photon in the bowtie is shared, so to speak, with the quantum dot. The coupling was sufficiently strong to be observed even when the gaps contained a single quantum dot, as opposed to several. The bowtie nanoparticles could thus be prompted to switch from one state to another: from a state without coupling to quantum dots, before exposure to light, to the mixed state characterized by strong coupling, following such exposure.
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Nice that they are trying to ensure this. However, as we integrate more tech into Biocomputing space and our efforts in achieving singularity; you will need some level of a medical/ or bio background.
It’s hard enough for IT security managers to keep with the latest in conventional computing. Cloud Security Alliance and the US government are trying to make sure you don’t need a physics degree, too.
Finally, could we see no more confusions in our voice interfaces.
Perfecting voice interfaces.
The entire mobile industry is moving rapidly towards voice as the primary input element for our devices.
Fog, blizzards, gusts of wind — poor weather can often make the operation of rescue helicopters a highly risky business, and sometimes even impossible. A new helmet-mounted display, developed by researchers at the Technical University of Munich (TUM), may in the future be able to help pilots detect hazards at an early stage, even when their visibility is severely impaired: the information required to do this is created in an on-board computer and imported into digital eye glasses.
A new study has shown that this augmented reality improves the performance of pilots.
Thick clouds hang over the Tegernsee. The range of sight is just a few hundred meters. Under normal circumstances, a helicopter would not be allowed to take off in such weather — the danger that the pilot would not be able to react in time to a construction crane, a power line or a mountain would be too great.
Get ready.
China will launch the world’s first quantum satellite next month to demonstrate a series of advanced technologies such as hacker-proof communications and quantum teleportation.
Ground testing and quality checks on the satellite had finished at the Chinese Academy of Sciences, and it would depart for the Jiuquan Satellite Launch Centre in Inner Mongolia early this month for a launch aboard a Long March 2D rocket in the middle of next month, according to a report on the central government’s website posted on Friday.
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