http://phys.org/physics-news/quantum-physics/ en-us Phys.org Phys.Org provides the latest news on quantum physics, wave particle duality, quantum theory, quantum mechanics, quantum entanglement, quantum teleportation, and quantum computing. (Phys.org) —In order to better understand how the laws governing the quantum and classical regimes are related to one another, physicists have performed an experiment allowing them to observe a quantum-to-classical transition in a simple closed quantum system. The results suggest that classical behavior may be an innate property of certain isolated quantum systems such as the one studied here, and can emerge from quantum physics under certain conditions. http://phys.org/news288618805.html Physics - Quantum Physics 2013-05-24T12:53:43-07:00 Physicists understand perfectly well why a fridge magnet sticks to certain metallic surfaces. But there are more exotic forms of magnetism whose properties remain unclear, despite decades of intense research. An important step towards filling these gaps comes now from Tilman Esslinger and his group at the Department of Physics. http://phys.org/news288535584.html Physics - Quantum Physics 2013-05-23T14:00:07-07:00 Research teams from UW-Milwaukee and the University of York investigating the properties of ultra-thin films of new materials are helping bring quantum computing one step closer to reality. http://phys.org/news288515763.html Physics - Quantum Physics 2013-05-23T08:30:01-07:00 To describe the microscopic properties of matter and its interaction with the external world, quantum mechanics uses wave functions, whose structure and time dependence is governed by the Schrödinger equation. In atoms, electronic wave functions describe - among other things - charge distributions existing on length-scales that are many orders of magnitude removed from our daily experience. In physics laboratories, experimental observations of charge distributions are usually precluded by the fact that the process of taking a measurement changes a wave function and selects one of its many possible realizations. For this reason, physicists usually know the shape of charge distributions through calculations that are shown in textbooks. That is to say, until now. An international team coordinated by researchers from the Max Born Institute has succeeded in building a microscope that allows magnifying the wave function of excited electronic states of the hydrogen atom by a factor of more than twenty-thousand, leading to a situation where the nodal structure of these electronic states can be visualized on a two-dimensional detector. http://phys.org/news288430300.html Physics - Quantum Physics 2013-05-22T08:50:03-07:00 One of the many promising applications of quantum mechanics in the information sciences is quantum key distribution (QKD), in which the counterintuitive behavior of quantum particles guarantees that no one can eavesdrop on a private exchange of data without detection. http://phys.org/news288340062.html Physics - Quantum Physics 2013-05-21T07:27:57-07:00 (Phys.org) —Entanglement, by general consensus of physicists, is the weirdest part of quantum science. To say that two particles, A and B, are entangled means that they are actually two parts of an inseparable quantum thing. An important consequence of this inherent kinship is that measuring a property of A (say, the particle's polarization) is necessarily to know the corresponding property of B, even if you're not there with a detector to observe B and even if (as explained below) the existence of that property had no prior fixed value until the moment particle A was detected. http://phys.org/news288283333.html Physics - Quantum Physics 2013-05-20T15:42:22-07:00 Innsbruck physicists led by Rainer Blatt and Peter Zoller experimentally gained a deep insight into the nature of quantum mechanical phase transitions. They are the first scientists that simulated the competition between two rival dynamical processes at a novel type of transition between two quantum mechanical orders. They have published the results of their work in the journal Nature Physics. http://phys.org/news288248146.html Physics - Quantum Physics 2013-05-20T05:55:55-07:00 Second sound is a quantum mechanical phenomenon, which has been observed only in superfluid helium. Physicists from the University of Innsbruck, Austria, in collaboration with colleagues from the University of Trento, Italy, have now proven the propagation of such a temperature wave in a quantum gas. The scientists have published their historic findings in the journal Nature. http://phys.org/news287841227.html Physics - Quantum Physics 2013-05-15T13:00:11-07:00 Like small children, scientists are always asking the question 'why?'. One question they've yet to answer is why nature picked quantum physics, in all its weird glory, as a sensible way to behave. Researchers Corsin Pfister and Stephanie Wehner at the Centre for Quantum Technologies at the National University of Singapore tackle this perennial question in a paper published today in Nature Communications. http://phys.org/news287689070.html Physics - Quantum Physics 2013-05-14T11:00:01-07:00 Matter is categorized as either conductive, semi-conductive or resistive to the flow of electrons based on its bulk properties. However, physicists have now predicted a new state of matter in which the bulk of the material is insulating—resisting electron flow—but where electrons are free to move along its edges. The possibility of such a material, known as a 'topological insulator', has caused a great deal of excitement among physicists because its surface conducting states are unusually stable, making them a promising resource for use in quantum computers. Bohm-Jung Yang and Naoto Nagaosa from the RIKEN Center for Emergent Matter Science and their co‐workers have now devised a general theory for how an insulator changes into a topological insulator, which should aid in the practical search for such materials. http://phys.org/news287393985.html Physics - Quantum Physics 2013-05-10T08:39:52-07:00 (Phys.org) —From brain to heart to stomach, the bodies of humans and animals generate weak magnetic fields that a supersensitive detector could use to pinpoint illnesses, trace drugs – and maybe even read minds. Sensors no bigger than a thumbnail could map gas deposits underground, analyze chemicals, and pinpoint explosives that hide from other probes. http://phys.org/news287386752.html Physics - Quantum Physics 2013-05-10T06:39:19-07:00 (Phys.org) —An international collaboration led by researchers from the NIST Center for Nanoscale Science and Technology (CNST) has demonstrated a novel temporal filtering approach that improves the performance of triggered single photon sources based on solid-state quantum emitters. The technique is compatible with a broad class of photon sources, and is expected to provide significant improvements in areas important for applications in photonic quantum information science. The team included researchers from the CNST, the University of Maryland, the University of Rochester, and Politecnico di Milano, Italy. http://phys.org/news287308609.html Physics - Quantum Physics 2013-05-09T08:56:55-07:00 (Phys.org) —A computer science professor at Amherst College who recently devised and conducted experiments to test the speed of a quantum computing system against conventional computing methods will soon be presenting a paper with her verdict: quantum computing is, "in some cases, really, really fast." http://phys.org/news287257401.html Physics - Quantum Physics 2013-05-08T18:48:37-07:00 Michael Vasilyev's goals in his research are simply stated: increase by tenfold the amount of information that can be securely transmitted via the Internet and the distance over which that data can be transmitted. http://phys.org/news287238347.html Physics - Quantum Physics 2013-05-08T13:26:16-07:00 Researchers from the National Physical Laboratory, University of Strathclyde, Imperial College London and University of Glasgow have developed a portable way to produce ultracold atoms for quantum technology and quantum information processing. Their research has been published in the journal Nature Nanotechnology, where it is featured on the front cover. http://phys.org/news287223595.html Physics - Quantum Physics 2013-05-08T09:20:08-07:00 (Phys.org) —One of the more controversial theories of quantum gravity, which attempts to unify quantum mechanics and general relativity, is semiclassical gravity, which was proposed in the 1960s. As its name suggests, semiclassical gravity involves a combination of quantum and classical components. Specifically, matter obeys the rules of quantum mechanics while gravity and the spacetime structure obey classical laws. Many physicists think that integrating quantum and classical systems in this way creates physical contradictions and mathematical inconsistencies. However, in a new paper, physicists have closely analyzed exactly how classical gravity might affect the quantum properties of macroscopic objects, and found that the effects of semiclassical gravity may be experimentally detectable with state-of-the-art technology. http://phys.org/news287213873.html Physics - Quantum Physics 2013-05-08T09:00:01-07:00 (Phys.org) —Physicists at ETH Zurich have demonstrated one of the quintessential effects of quantum optics—known as the Hong-Ou-Mandel effect—with microwaves, whose frequency is 100'000 times lower than that of visible light. The experiment takes quantum optics into a new frequency regime and could eventually lead to new technological applications. http://phys.org/news287205985.html Physics - Quantum Physics 2013-05-08T04:26:36-07:00 (Phys.org) —In a recent paper available on arXiv, a team of researchers at New Mexico's Los Alamos National Laboratory has revealed they've been running a quantum network for 2 1/2 years. The network is hub-and-spoke based, the team reports, and allows for perfectly secure messaging except at the hub. http://phys.org/news287139027.html Physics - Quantum Physics 2013-05-07T10:00:02-07:00 (Phys.org) —Frustration crops up throughout nature when conflicting constraints on a physical system compete with one another. The way nature resolves these conflicts often leads to exotic phases of matter that are poorly understood. This week's issue of Science Magazine features new results from the research group of Christopher Monroe at the JQI, where they explored how to frustrate a quantum magnet comprised of sixteen atomic ions – to date the largest ensemble of qubits to perform a simulation of quantum matter. http://phys.org/news286815176.html Physics - Quantum Physics 2013-05-03T15:53:11-07:00 (Phys.org) —There has been a lot of talk recently about the possibility of building what has come to be known as a time crystal. In February 2012, Frank Wilczek originally proposed the idea that under certain conditions, physical structures can move in a repeating pattern without expending any energy. Last June, a group of researchers at Berkeley proposed a time crystal could be realized as a persistently rotating ring of charged atoms. Unfortunately a problem with that approach was pointed out by Patrick Bruno, who noted that to be a time crystal, an object must exhibit perpetual motion in its lowest energy state—the ground state. Commenting in Physical Review Letters in March, Bruno showed that the particular example described by Wilczek was actually one of a system in an excited state, and therefore not a time crystal. Taking advantage of recent breakthroughs in the construction of low noise ion traps, Berkeley researchers now plan to build an ion trap that will satisfy the critics. http://phys.org/news286813095.html Physics - Quantum Physics 2013-05-03T15:18:34-07:00 Virtually every material undergoes atomic-level ordering when cooled to temperatures approaching absolute zero. Liquid water, for example, is frozen into atomically ordered crystalline ice. However, condensed matter physicists have theorized that it may be possible to achieve a state called a quantum spin liquid, in which quantum-mechanical effects or the structure of the atomic lattice hinder the development of atomic order while retaining strong electronic interactions. Seiji Yunoki and colleagues from the RIKEN Center for Emergent Matter Science and the RIKEN Advanced Institute for Computational Science have now shown through detailed calculations that achieving the quantum spin liquid state may be more difficult than previously thought. http://phys.org/news286702363.html Physics - Quantum Physics 2013-05-02T08:32:56-07:00 By using light, researchers at UC Santa Barbara have manipulated the quantum state of a single atomic-sized defect in diamond –– the nitrogen-vacancy center –– in a method that not only allows for more unified control than conventional processes, but is more versatile, and opens up the possibility of exploring new solid-state quantum systems. Their results are published in the latest edition of the Proceedings of the National Academy of Sciences. http://phys.org/news286640860.html Physics - Quantum Physics 2013-05-01T15:28:09-07:00 An Australian team led by researchers at the University of New South Wales has achieved a breakthrough in quantum science that brings the prospect of a network of ultra-powerful quantum computers - connected via a quantum internet –closer to reality. http://phys.org/news286625403.html Physics - Quantum Physics 2013-05-01T13:00:13-07:00 A quantum computer is controlled by the laws of quantum physics; it promises to perform complicated calculations, or search large amounts of data, at a speed that exceeds by far those that today's fastest supercomputers are capable of. http://phys.org/news286541913.html Physics - Quantum Physics 2013-04-30T11:58:45-07:00 (Phys.org) —Mathematics is, in essence, an artificial language for precisely articulating theories about the physical world. Unlike natural language, however, translating different classes of mathematics can be difficult at best. Such is the case encountered in the attempt to unify general relativity and quantum theory, since they are expressed in differential geometry and functional analysis, respectively. That being said, spectral geometry – a field in mathematics which concerns relationships between geometric structures of manifolds and spectra of canonically defined differential operators – may resolve this long-standing quandary by allowing spacetime to be treated as simultaneously continuous and discrete, essentially relating the frequency-based ringing of the fabric of spacetime to its manifold-based shape. Recently, scientists at California Institute of Technology, Princeton University, University of Waterloo, and University of Queensland normalized and segmented spectral geometry into small, finite-dimensional steps. They then demonstrated their approach of calculating the shapes of two-dimensional objects from their vibrational spectra as being viable in two, and possibly more, dimensions. http://phys.org/news286449018.html Physics - Quantum Physics 2013-04-29T11:00:01-07:00 (Phys.org) —The size of an object can be measured in many ways, such as by its mass, volume, or even the number of atoms it contains. And when it comes to quantum physics, "macroscopic" objects are considered to be larger than "quantum" ones, since the former are usually described by classical laws and the latter by quantum laws. However, physicists have been challenging the boundary between these two realms by performing experiments that show that multiparticle objects can exist in quantum superpositions. But there has been no standard measure of macroscopicity until now, as a team of physicists has proposed that the macroscopicity of an object can be measured in terms of certain parameters of the experiment used to probe its quantum superposition, rather than as a single property of the object itself. http://phys.org/news286207660.html Physics - Quantum Physics 2013-04-26T15:08:34-07:00 (Phys.org) —New research shows that movement of the ring-like molecule pyrrole over a metal surface runs counter to the centuries-old laws of 'classical' physics that govern our everyday world. http://phys.org/news286195025.html Physics - Quantum Physics 2013-04-26T11:37:12-07:00 These components, called quantum bits, are fragile and susceptible to outside interference, making them easier to control when isolated in cells of four. Now scientists from Oxford and Singapore report in Nature Communications a way these cells could be networked up with light even if these links are 'noisy' and unreliable. http://phys.org/news286096041.html Physics - Quantum Physics 2013-04-25T08:30:05-07:00 (Phys.org) —Researchers at TU Delft in the Netherlands have managed to bring two electrons, three meters from each other, into a quantum- entangled state. This result marks a major step towards realizing a quantum network that can be used to connect future quantum computers and to send information in a completely secure way by means of 'teleportation'. The results have been published online on April 24 in Nature. http://phys.org/news286048535.html Physics - Quantum Physics 2013-04-24T18:55:43-07:00 An international team of scientists has shed new light on a fundamental area of physics which could have important implications for future electronic devices and the transfer of information at the quantum level. http://phys.org/news285925816.html Physics - Quantum Physics 2013-04-23T08:50:28-07:00