Weak Values May Not Be Quantum
Over the past 20 years, a strange idea called a “weak value” has taken root in quantum information science. Many of the things you can do with quantum technologies entail being able to gain information from quantum systems. But there is a quantum conundrum: we can’t say what a particle is doing when we’re not looking at it, but when we do look at it, we change its behavior.
But what if we could look “a little”? Well, that’s a weak measurement, a concept which is central to the notion of a weak value. The basic idea of weak measurement is to gain a little bit of information about a quantum system by only disturbing it a little bit; by doing this many times, one can ultimately gain quite a bit of information about the system. Weak measurements have applications in quantum information technologies such as quantum feedback control and quantum communications.
Read more: http://www.laboratoryequipment.com/news/2014/09/weak-values-may-not-be-quantum
Team Smashes Own Quantum Teleportation Record
Physicists at the Université de Genève (UNIGE) have succeeded in teleporting the quantum state of a photon to a crystal over 25 kilometers of optical fiber. The experiment, carried out in the laboratory of Prof. Nicolas Gisin, constitutes a first, and pulverizes the previous record of six kilometers achieved 10 years ago by the same UNIGE team. Passing from light into matter, using teleportation of a photon to a crystal, shows that, in quantum physics, it is not the composition of a particle which is important, but rather its state, since this can exist and persist outside such extreme differences as those which distinguish light from matter. The results obtained by Félix Bussières and his colleagues are reported in the latest edition of Nature Photonics.
Quantum physics, and with it the UNIGE, is again being talked about around the world with the Marcel Benoist Prize for 2014 being awarded to Gisin, and the publication of experiments in Nature Photonics. The latest experiments have enabled verifying that the quantum state of a photon can be maintained whilst transporting it into a crystal without the two coming directly into contact. One needs to imagine the crystal as a memory bank for storing the photon’s information; the latter is transferred over these distances using the teleportation effect.
Read more: http://www.laboratoryequipment.com/news/2014/09/team-smashes-own-quantum-teleportation-record
Strange Quantum Changes Studied Near Absolute Zero
Heat drives classical phase transitions — think solid, liquid and gas — but much stranger things can happen when the temperature drops. If phase transitions occur at the coldest temperatures imaginable, where quantum mechanics reigns, subtle fluctuations can dramatically transform a material.
Scientists from the U.S. Department of Energy’s Brookhaven National Laboratory and Stony Brook Univ. have explored this frigid landscape of absolute zero to isolate and probe these quantum phase transitions with unprecedented precision.
Read more: http://www.laboratoryequipment.com/news/2014/09/strange-quantum-changes-studied-near-absolute-zero
New Tech Studies Small Clusters of Atoms
Physicists at the Univ. of York, working with researchers at the Universities of Birmingham and Genoa, have developed new technology to study atomic vibration in small particles, revealing a more accurate picture of the structure of atomic clusters where surface atoms vibrate more intensively than internal atoms.
Using new computer technology based on gaming machines, scientists were able to use a combination of molecular dynamics and quantum mechanics calculations to simulate the electron microscopy of gold particles. By modelling the atomic vibration of individual atoms in such clusters realistically, external atoms on the surface of the structure can be seen to vibrate more than internal atoms.
Read more: http://www.laboratoryequipment.com/news/2014/08/new-tech-studies-small-clusters-atoms
Researchers at Washington State Univ. have used a super-cold cloud of atoms that behaves like a single atom to see a phenomenon predicted 60 years ago and witnessed only once since. The phenomenon takes place in the seemingly otherworldly realm of quantum physics and opens a new experimental path to potentially powerful quantum computing.
Working out of a lab in WSU’s Webster Hall, physicist Peter Engels and his colleagues cooled about one million atoms of rubidium to 100 billionths of a degree above absolute zero. There was no colder place in the universe, says Engels, unless someone was doing a similar experiment elsewhere on Earth or on another planet.
Read more: http://www.laboratoryequipment.com/news/2014/06/researchers-see-phenomenon-predicted-60-years-ago
Quantum Photon Properties Revealed in Plasmon
For years, researchers have been interested in developing quantum computers — the theoretical next generation of technology that will outperform conventional computers. Instead of holding data in bits, the digital units used by computers today, quantum computers store information in units called “qubits.” One approach for computing with qubits relies on the creation of two single photons that interfere with one another in a device called a waveguide. Results from a recent applied science study at Caltech support the idea that waveguides coupled with another quantum particle — the surface plasmon — could also become an important piece of the quantum computing puzzle.
Read more: http://www.laboratoryequipment.com/news/2014/04/quantum-photon-properties-revealed-plasmon
Quasi-Particles Move Between Graphene Layers
Belgian scientists have used a particle physics theory to describe the behavior of particle-like entities, referred to as excitons, in two layers of graphene, a one-carbon-atom-thick honeycomb crystal. In a paper published in Springer’s EPJ B, Michael Sarrazin from the Univ. of Namur, and Fabrice Petit from the Belgian Ceramic Research Centre in Mons, studied the behavior of excitons in a bilayer of graphene through an analogy with excitons evolving in two abstract parallel worlds, described with equations typically used in high-energy particle physics.
The authors used the equations reflecting a theoretical world consisting of a bi-dimensional space sheet — a so-called brane — embedded in a space with three dimensions. Specifically, the authors described the quantum behavior of excitons in a universe made of two such brane worlds. They then made an analogy with a bilayer of graphene sheets, in which quantum particles live in a separate space-time.
Read more: http://www.laboratoryequipment.com/news/2014/02/quasi-particles-move-between-graphene-layers
Tiny Components a Step Toward Quantum Computer
Scientists and engineers from an international collaboration led by Mark Thompson from the Univ. of Bristol have, for the first time, generated and manipulated single particles of light on a silicon chip – a major step forward in the race to build a quantum computer.
Quantum computers and quantum technologies in general are widely anticipated as the next major technology advancement, and are poised to replace conventional information and computing devices in applications ranging from ultra-secure communications and high-precision sensing to immensely powerful computers. Quantum computers themselves will likely lead to breakthroughs in the design of new materials and in the discovery of new medical drugs.
Read more: http://www.laboratoryequipment.com/news/2014/01/tiny-components-step-toward-quantum-computer
In a recent study, published in Science, researchers have been able to observe, for the first time, the collective spin dynamics of ultra-cold fermions with large spins.
Understanding collective behavior of ultra-cold quantum gases is of great interest since it is intimately related to many encountered systems in nature such as human behavior, swarms of birds, traffic jam, sand dunes, neutron stars, fundamental magnetic properties of solids or even super-fluidity or super-conductivity. In all of these everyday life examples, collective behavior plays a crucial role since all participating objects move — voluntarily or not — synchronously.
Read more: http://www.laboratoryequipment.com/news/2014/01/researchers-see-macro-behaviors-ultra-cold-quantum-gases
Physicists at the Univ. of Basel have been successful in generating photons — the quantum particles of light — with only one color. This is useful for quantum information science. The scientists have actively stabilized the wavelength of the photons emitted by a semiconductor thereby neutralizing the charge noise in the semiconductor. The results were developed in close collaboration with the Universities of Bochum, Paderborn and Lyon and have been published in the magazine Physical Review X.
Light consists of quantum particles, so-called photons. With a single photon it is possible to transfer quantum information. The information can be encoded in the polarization or in the phase of the photons’ wave packets and can be used in quantum communication and computation. In such applications, a single-photon source, a device that emits photons one by one, is a prerequisite. One of the most promising platforms for single-photon sources is based on semiconductor quantum dots. One major unsolved problem is, however, that the “color” (or wavelength) of the photons emitted by a quantum dot is not locked to a precise value, rather, it wanders around randomly.
Read more: http://www.laboratoryequipment.com/news/2013/11/scientists-are-developing-stable-quantum-light-source
Researchers Make Most Powerful Terahertz Quantum Cascade Laser
Whether it is diagnostic imaging, analysis of unknown substances or ultrafast communication – terahertz radiation sources are becoming more and more important. At the Vienna Univ. of Technology, an important breakthrough has been achieved.
Terahertz waves are invisible, but incredibly useful; they can penetrate many materials which are opaque to visible light and they are perfect for detecting a variety of molecules. Terahertz radiation can be produced using tiny quantum cascade lasers, only a few millimeters wide. This special kind of lasers consists of tailor made semiconductor layers on a nanometer scale. At TU Vienna a new world record has now been set; using a special merging technique, two symmetrical laser structures have been joined together, resulting in a quadruple intensity of laser light.
Read more: http://www.laboratoryequipment.com/news/2013/10/researchers-make-most-powerful-terahertz-quantum-cascade-laser
Nanostructures Could Offer Way to Control Quantum Effect… Once a Mystery Is Solved
You might think that a pair of parallel plates hanging motionless in a vacuum just a fraction of a micrometer away from each other would be like strangers passing in the night — so close but destined never to meet. Thanks to quantum mechanics, you would be wrong.
Scientists working to engineer nanoscale machines know this only too well as they have to grapple with quantum forces and all the weirdness that comes with them. These quantum forces, most notably the Casimir effect, can play havoc if you need to keep closely spaced surfaces from coming together.
Read more: http://www.laboratoryequipment.com/news/2013/10/nanostructures-could-offer-way-control-quantum-effect-once-mystery-solved
Physicist Solves ‘Schrödinger’s Cat’ Debate
Univ. of Arkansas physicist Art Hobson has offered a solution, within the framework of standard quantum physics, to the long-running debate about the nature of quantum measurement.
In an article published by Physical Review A, a journal of the American Physical Society, Hobson argues that the phenomenon known as “nonlocality” is key to understanding the measurement problem illustrated by “Schrödinger’s cat.”
Read more: http://www.laboratoryequipment.com/news/2013/08/physicist-solves-schr%C3%B6dingers-cat-debate
An alternative and novel concept in electronics utilizes the wave quantum number of the electron in a crystalline material to encode information. In a new article in Nature Materials, researchers propose using this valley degree of freedom in diamond to enable valleytronic information processing or as a new route to quantum computing.
In electronic circuits, bits of information (1:s and 0:s) are encoded by the presence or absence of electric charge. For fast information processing, e.g. in computer processors or memories, charges have to be moved around at high switching rates. Moving charges requires energy, which inevitably causes heating and gives rise to a fundamental limit to the switching rate. As an alternative it is possible to utilize other properties than the charge of electrons to encode information and thereby avoid this fundamental limit. An example of this is “spintronics” where the spin of the electron is used to carry information.
Read more: http://www.laboratoryequipment.com/news/2013/07/concept-aids-development-%E2%80%98valleytronics%E2%80%99-diamonds
New Technology Will Test 50-Year-Old Physics Theory
Physicists working at the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (JQI) are edging ever closer to getting really random.
Their work — a photon source that provides the most efficient delivery of a particularly useful sort of paired photons yet reported — sounds prosaic enough, but it represents a new high-water mark in a long-term effort toward two very different and important goals, a definitive test of a key feature of quantum theory and improved security for Internet transactions.
Read more: http://www.laboratoryequipment.com/news/2013/06/new-technology-will-test-50-year-old-physics-theory