The battle over distance records sets up a fascinating race to be the first to teleport to an orbiting satellite Just a couple of weeks ago, we discussed a Chinese experiment in which physicists teleported photons over a distance of almost 100 kilometres. That’s almost an order of magnitude more than previous records. Today, European physicists… [Read more…]
May 15, 2012
… On A Quantum Computer Quantum tunnelling had always been thought too complex to simulate on today’s simple quantum computers. Now a new approach to quantum computing has changed that and opens the door to more complex simulations The exploitation of quantum weirdness for computing is one of the great goals of modern physics. It’s… [Read more…]
May 11, 2012
Juan Yin, He Lu, Ji-Gang Ren, Yuan Cao, Hai-Lin Yong, Yu-Ping Wu, Chang Liu, Sheng-Kai Liao, Yan Jiang, Xin-Dong Cai, Ping Xu, Ge-Sheng Pan, Jian-Yu Wang, Yu-Ao Chen, Cheng-Zhi Peng, Jian-Wei Pan With the help of quantum entanglement, quantum communication can be achieved between arbitrarily distant places without passing through intermediate locations by quantum teleportation.… [Read more…]
May 9, 2012
Matthew F. Pusey, Jonathan Barrett & Terry Rudolph Quantum states are the key mathematical objects in quantum theory. It is therefore surprising that physicists have been unable to agree on what a quantum state truly represents. One possibility is that a pure quantum state corresponds directly to reality. However, there is a long history of… [Read more…]
May 8, 2012
GianCarlo Ghirardi, Raffaele Romano Recently, various new proposals of superluminal transmission of information have appeared in the literature. Since they make systematic resort to recent formal and practical improvements in quantum mechanics, the old theorems proving the impossibility of such a performance must be adapted to the new scenario. In this paper we consider some… [Read more…]
April 25, 2012
… using a quantum device Jian-Shun Tang, Yu-Long Li, Chuan-Feng Li, Guang-Can Guo Bohr’s principle of complementarity lies at the central place of quantum mechanics, according to which the light is chosen to behave as a wave or particles, depending on some exclusive detecting devices. Later, intermediate cases are found, but the total information of… [Read more…]
April 23, 2012
Art Hobson Quantum foundations are still unsettled, with harmful effects on science and society. By now it should be possible to obtain consensus on at least one issue: Are the fundamental constituents fields or particles? Experiment and theory imply a universe made of unbounded fields rather than bounded particles. This is especially clear for relativistic… [Read more…]
April 21, 2012
A fundamental prediction of superconductivity theory has been demonstrated in the lab for the first time. An international team of physicists has observed coherent quantum phase slip, a phenomenon similar to the well-known Josephson effect in which magnetic flux takes the place of electric charge. Its discovery has fundamental implications for our understanding of macroscopic… [Read more…]
April 21, 2012
G. A. Kazakov, A. N. Litvinov, V. I. Romanenko, L. P. Yatsenko, A. V. Romanenko, M. Schreitl, G. Winkler, T. Schumm The 7.8 eV nuclear isomer transition in 229-Thorium has been suggested as an etalon transition in a new type of optical frequency standard. Here we discuss the construction of a “solid-state nuclear clock” from… [Read more…]
April 19, 2012
Spin–orbital separation in the quasi-one-dimensional Mott insulator Sr2CuO3 J. Schlappa et al When viewed as an elementary particle, the electron has spin and charge. When binding to the atomic nucleus, it also acquires an angular momentum quantum number corresponding to the quantized atomic orbital it occupies. Even if electrons in solids form bands and delocalize… [Read more…]
April 16, 2012
… a lesson for quantum gravity Stefano Finazzi, Stefano Liberati, Lorenzo Sindoni For almost a century, the cosmological constant has been a mysterious object, in relation to both its origin and its very small value. By using a Bose-Einstein condensate analogue model for gravitational dynamics, we address here the cosmological constant issue from an analogue… [Read more…]
April 12, 2012
The Fastest-Ever Random Number Generator Conjures Digits from Subatomic Noise in a Vacuum It was once thought that vacuums–like the vacuum of space–contained nothing. No particles, no sound, just empty darkness. But it has since come to light, thanks to discoveries in quantum physics, that virtual sub-atomic particles constantly and spontaneously appear and disappear, even… [Read more…]
April 11, 2012
Gilles Brassard, Paul Raymond-Robichaud Quantum Mechanics is generally considered to be the ultimate theory capable of explaining the emergence of randomness by virtue of the quantum measurement process. Therefore, Quantum Mechanics can be thought of as God’s wonderfully imaginative solution to the problem of providing His creatures with Free Will in an otherwise well-ordered Universe.… [Read more…]
April 10, 2012
… and nonlocal decision at detection Antoine Suarez I discuss an experiment demonstrating nonlocality and conservation of energy under the assumption that the decision of the outcome happens at detection. The experiment does not require Bell’s inequalities and is loophole-free. I further argue that the local hidden variables assumed in Bell’s theorem involve de Broglie’s… [Read more…]
March 18, 2012
Einstein’s theory of gravity and quantum physics are expected to merge at the Planck-scale of extremely high energies and on very short distances. At this scale, new phenomena could arise. However, the Planck-scale is so remote from current experimental capabilities that tests of quantum gravity are widely believed to be nearly impossible. Now an international… [Read more…]
March 13, 2012
Ever wonder what Einstein really did? He showed that light was a particle! http://youtu.be/hSgIDgGpRpk
March 8, 2012
Einstein’s “Spooky Action At a Distance” Paradox Older Than Thought Einstein’s famous critique of quantum mechanics first emerged in 1930, five years earlier than thought, according to a new analysis of his work Einstein’s phrase “spooky action at a distance” has become synonymous with one of the most famous episodes in the history of physics–his… [Read more…]
March 3, 2012
A. D. Ernest A quantum expansion parameter, analogous to the Hubble parameter in cosmology, is defined for a free particle quantum wavefunction. By considering the universe as an initial single Gaussian quantum wavepacket whose mass is that of present-day observable universe and whose size is that of the Planck Length at the Planck Time, it… [Read more…]
March 2, 2012
Quest for quirky quantum particles may have struck gold Evidence for elusive Majorana fermions raises possibilities for quantum computers. Eugenie Samuel Reich Getting into nanoscience pioneer Leo Kouwenhoven’s talk at the American Physical Society’s March meeting in Boston, Massachusetts, today was like trying to board a subway train at rush hour. The buzz in the corridor was… [Read more…]
February 28, 2012
Nobody knows whether humans can access exotic images based on quantum entanglement. Now one physicist has designed an experiment to find out The strange rules of the quantum world lead to many weird phenomena. One of these is the puzzling process of quantum imaging, which allows images to form in hitherto unimagined ways. Researchers begin… [Read more…]
February 22, 2012
Simon J.D. Phoenix, Faisal Shah Khan We present a perspective on quantum games that focuses on the physical aspects of the quantities that are used to implement a game. If a game is to be played, it has to be played with objects and actions that have some physical existence. We call such games playable.… [Read more…]
February 16, 2012
Read also: Time crystals could behave almost like perpetual motion machines If crystals exist in spatial dimensions, then they ought to exist in the dimension of time too, says Nobel prize-winning physicist One of the most powerful ideas in modern physics is that the Universe is governed by symmetry. This is the idea that certain… [Read more…]
February 15, 2012
The creation of increasingly large multipartite entangled states is not only a fundamental scientific endeavour in itself, but is also the enabling technology for quantum information. Tremendous experimental effort has been devoted to generating multiparticle entanglement with a growing number of qubits. So far, up to six spatially separated single photons have been entangled based… [Read more…]
January 24, 2012
Rice University physicists have built an accurate model of part of the solar system inside a single atom. In a new paper in Physical Review Letters, Rice’s team and collaborators from Oak Ridge National Laboratory and the Vienna University of Technology showed they could make an electron orbit the atomic nucleus in the same way… [Read more…]
January 23, 2012
The Millikan oil drop experiment, published in final form in 1913, demonstrated that charge comes in discrete chunks and was a bridge between classical electromagnetism and modern quantum physics. Researchers now routinely isolate single electrons in quantum dots, but a century ago the state-of-the-art charge-trapping device was a droplet of clock oil. Robert Millikan’s oil… [Read more…]
January 23, 2012
Antonio Barletta There is a huge number of excellent and comprehensive textbooks on quantum mechanics. They mainly differ for the approach, more or less oriented to the formalism rather than to the phenomenology, as well as for the topics covered. These lectures have been based mainly on the classical textbook by Gasiorowicz (1974). I must… [Read more…]
January 18, 2012
Fotini Markopoulou The idea that the Universe is a program in a giant quantum computer is both fascinating and suffers from various problems. Nonetheless, it can provide a unified picture of physics and this can be very useful for the problem of Quantum Gravity where such a unification is necessary. In previous work we proposed… [Read more…]
January 12, 2012
Jeremy Schiff, Bill Poirier We present a self-contained formulation of spin-free nonrelativistic quantum mechanics that makes no use of wavefunctions or complex amplitudes of any kind. Quantum states are represented as ensembles of real-valued quantum trajectories, obtained by extremizing an action and satisfying energy conservation. The theory applies for arbitrary configuration spaces and system dimensionalities.… [Read more…]
January 8, 2012
New research lays groundwork for new generation of ultrasensitive gyroscopes to measure gravity, magnetic field, and create quantum circuits A Cambridge team have built a semiconductor chip that converts electrons into a quantum state that emits light but is large enough to see by eye. Because their quantum superfluid is simply set up by shining… [Read more…]
January 4, 2012
…revisited Brian D. Josephson Abstract It is hypothesised, following Conrad et al. (1988) that quantum physics is not the ultimate theory of nature, but merely a theoretical account of the phenomena manifested in nature under particular conditions. These phenomena parallel cognitive phenomena in biosystems in a number of ways and are assumed to arise from… [Read more…]
January 4, 2012
Shahar Hod Black-hole spacetimes with a “photonsphere”, a hypersurface on which massless particles can orbit the black hole on circular null geodesics, are studied. We prove that among all possible trajectories (both geodesic and non-geodesic) which circle the central black hole, the null circular geodesic is characterized by the shortest possible orbital period as measured… [Read more…]
December 27, 2011
… to electron diffraction for one and two slits, analytical results Mathieu Beau (STP-DIAS) In this article we present an analytic solution of the famous problem of diffraction and interference of electrons through one and two slits (for simplicity, only the one-dimensional case is considered). It can thus be considered a complement to a recent… [Read more…]
December 13, 2011
Data analysis and simulation H. De Raedt, K. Michielsen, F. Jin Data produced by laboratory Einstein-Podolsky-Rosen-Bohm (EPRB) experiments is tested against the hypothesis that the statistics of this data is given by quantum theory of this thought experiment. Statistical evidence is presented that the experimental data, while violating Bell inequalities, does not support this hypothesis.… [Read more…]
December 9, 2011
Christoph Adami Information theory is a statistical theory dealing with the relative state of detectors and physical systems. Because of this physicality of information, the classical framework of Shannon needs to be extended to deal with quantum detectors, perhaps moving at relativistic speeds, or even within curved space-time. Considerable progress toward such a theory has… [Read more…]
December 1, 2011
A new project known as “Danceroom Spectroscopy” represents a true fusion of art and science, resulting in a spectacular visual art show that is driven by real physical laws. http://youtu.be/y4MGYFeZ0AE
November 28, 2011
Dragan Slavkov Hajdukovic Abstract Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the nonexistence of dark… [Read more…]
November 20, 2011
D. Nanopoulos Abstract Recent developments/efforts to understand aspects of the brain function at the subneural level are discussed. MicroTubules (MTs), protein polymers constructing the cytoskeleton, participate in a wide variety of dynamical processes in the cell. Of special interest to us is the MTs participation in bioinformation processes such as learning and memory, by possessing… [Read more…]
November 20, 2011
The wavefunction is a real physical object after all, say researchers. Eugenie Samuel Reich At the heart of the weirdness for which the field of quantum mechanics is famous is the wavefunction, a powerful but mysterious entity that is used to determine the probabilities that quantum particles will have certain properties. Now, a preprint posted online on… [Read more…]
November 17, 2011
Scientists at Chalmers have succeeded in creating light from vacuum – observing an effect first predicted over 40 years ago. The results have been published in the journal Nature. In an innovative experiment, the scientists have managed to capture some of the photons that are constantly appearing and disappearing in the vacuum. The experiment is… [Read more…]
November 15, 2011
Matthew F. Pusey, Jonathan Barrett, Terry Rudolph Quantum states are the key mathematical objects in quantum theory. It is therefore surprising that physicists have been unable to agree on what a quantum state represents. There are at least two opposing schools of thought, each almost as old as quantum theory itself. One is that a… [Read more…]
November 14, 2011
Timothy C. Ralph, Tony G. Downes Relativistic quantum information combines the informational approach to understanding and using quantum mechanics systems – quantum information – with the relativistic view of the universe. In this introductory review we examine key results to emerge from this new field of research in physics and discuss future directions. A particularly… [Read more…]
November 5, 2011
On ‘Nothing’ Adam R. Brown and Alex Dahlen Abstract Nothing-the absence of spacetime-can be either an endpoint of tunneling, as in the bubble of nothing, or a starting point for tunneling, as in the quantum creation of a universe. We argue that these two tunnelings can be treated within a unified framework, and that, in… [Read more…]
November 1, 2011
Richard Healey I offer an account of how the quantum theory we have helps us explain so much. The account depends on a pragmatist interpretation of the theory: This takes a quantum state to serve solely as a source of sound advice to physically situated agents on the content and appropriate degree of belief about… [Read more…]
October 18, 2011
Researchers have created a new material that can produce three or more free electrons every time it absorbs a single photon. This is unlike conventional semiconductors, which produce just one free electron per photon. Based on tiny semiconductor structures called quantum dots, the new material – developed by researchers at Delft University of Technology in… [Read more…]
October 4, 2011
Rice University physicists have created a tiny “electron superhighway” that could one day be useful for building a quantum computer, a new type of computer that will use quantum particles in place of the digital transistors found in today’s microchips. n a recent paper in Physical Review Letters, Rice physicists Rui-Rui Du and Ivan Knez… [Read more…]
October 4, 2011
Modifications of quantum mechanics are considered, in which the state vector of any system, large or small, undergoes a stochastic evolution. The general class of theories is described, in which the probability distribution of the state vector collapses to a sum of delta functions, one for each possible final state, with coefficients given by the… [Read more…]
September 22, 2011
Strong long-scale gravitational waves can explain cosmic acceleration within the context of general relativity without resorting to the assumption of exotic forms of matter such as quintessence. The existence of these gravitational waves in sufficient strength to cause observed acceleration can be compatible with the cosmic microwave background under reasonable physical circumstances. An instance of… [Read more…]
September 22, 2011
We consider the problem of measurement using the Lindblad equation, which allows the introduction of time in the interaction between the measured system and the measurement apparatus. We used analytic results, valid for weak system-environment coupling, obtained for a two-level system in contact with a measurer (Markovian interaction) and a thermal bath (non-Markovian interaction), where… [Read more…]
September 21, 2011
Computer scientists have built a superconducting number cruncher with a Von Neumann architecture that paves the way for a new era of quantum computation Back in 1946, the world’s first general purpose electronic computer was switched on at the University of Pennsylvania. The huge processing power of ENIAC (Electronic Numerical Integrator And Computer) stunned the… [Read more…]
September 11, 2011
A quantum phenomenon allows detectors which sense oscillations of space-time to measure with 50 percent more accuracy. Measuring at the limits of the laws of nature – this is the challenge which researchers repeatedly take up in their search for gravitational waves. The interferometers they use here measure with such sensitivity that a particularquantum phenomenon of light… [Read more…]
September 8, 2011
These notes are based on lectures given by Michael Green during Part III of the Mathematics Tripos (the Certificate for Advanced Study in Mathematics) in the Spring of 2003. The course provided an introduction to string theory, focussing on the Bosonic string, but treating the superstring as well. A background in quantum field theory and… [Read more…]
September 6, 2011
The first digital “quantum simulator” based on trapped ions has been built by physicists in Austria. The system, developed by Ben Lanyon and colleagues at the University of Innsbruck, comprises a number of trapped calcium ions that are manipulated using sequences of laser pulses. The team has used the system to simulate the time-evolution of… [Read more…]
September 5, 2011
The fuzziness and weird logic of the way particles behave applies surprisingly well to how humans think THE quantum world defies the rules of ordinary logic. Particles routinely occupy two or more places at the same time and don’t even have well-defined properties until they are measured. It’s all strange, yet true – quantum theory… [Read more…]
September 5, 2011
Physical research looks for clues to quantum properties of the gravitational field. On the basis of the common Schr\”odinger theory, a simple model of the quantization of a Friedmann universe comprising dust and radiation is investigated. With regard to energy quantization, the result suggests a universal limitation of the energy spacing between neighbouring quantum states… [Read more…]
September 3, 2011
By tightly focussing a laser eld onto a single cold ion trapped in front of a far-distant dielectric mirror, we could observe a quantum electrodynamic e ect whereby the ion behaves as the optical mirror of a Fabry-Perot cavity. We show that the amplitude of the laser eld is signi cantly altered due to a modi cation of… [Read more…]
September 2, 2011
A constant stabilization experiment of a quantum state has been successfully carried out for the first time by a team from the Laboratoire Kastler Brossel headed by Serge Haroche. The researchers succeeded in maintaining a constant number of photons in a high-quality microwave cavity. The results of their study are published in the online journal Nature on… [Read more…]
September 1, 2011
A new paradigm in quantum information processing has been demonstrated by physicists at UC Santa Barbara. Their results are published in this week’s issue of Science Express online. UCSB physicists have demonstrated a quantum integrated circuit that implements the quantum von Neumann architecture. In this architecture, a long-lived quantum random access memory can be programmed… [Read more…]
August 31, 2011
The Rabi model (RM) describes the simplest interaction between light and matter. In its semiclassical form, this model describes the coupling of a two-level system and a classical monochromatic field. The fully quantum model considers the same situation, with the light field quantized. Although this model has had an impressive impact on many fields of… [Read more…]
August 30, 2011
We discuss theoretical predictions for the thermal Casimir force and compare them with available experimental data. Special attention is paid to the recent claim of the observation of that effect, as predicted by the Drude model approach. We show that this claim is in contradiction with a number of experiments reported so far. We suggest… [Read more…]
August 24, 2011
The way gravity effects quantum particles proves that it cannot be an emergent phenomenon, says physicist. One of the most exciting ideas in modern physics is that gravity is not a traditional force, like electromagnetic or nuclear forces. Instead, it is an emergent phenomenon that merely looks like a traditional force. This approach has been… [Read more…]
August 19, 2011
This paper is prepared as a contribution to the proceedings after the 12th ICSSUR/Feynfest Conference held in Foz do Iguacu (Brazil) from 2 to 6 May 2011. In the first part I briefy report the topic of entropic uncertainty relations for position and momentum variables. Then I investigate the discrete Shannon entropies related to the… [Read more…]
August 18, 2011
A quantum clock working as a control device is examined. The quality of the control process is characterized by the magnitude of deviation of perturbed state from unperturbed state of the controlled system. Uncertainty relations that relate the time duration of the process and energy of the clock to the quality of the control are… [Read more…]
August 17, 2011
The derivation of the Heisenberg Uncertainty Principle (HUP) from the Uncertainty Theorem of Fourier Transform theory demonstrates that the HUP arises from the dependency of momentum on wave number that exists at the quantum level. It also establishes that the HUP is purely a relationship between the effective widths of Fourier transform pairs of variables… [Read more…]
August 17, 2011
Applications of Integrated Optics to quantum sources, detectors, interfaces, memories and linear optical quantum computing are described in this review. By their inherent compactness, efficiencies, and interconnectability, many of the demonstrated individual devices can clearly serve as building blocks for more complex quantum systems, that could also profit from the incorporation of other guided wave… [Read more…]
August 15, 2011
It is generally believed that classical regime emerges as a limiting case of quantum theory. Exploring such quantum-classical correspondences in a more transparent manner is central to the deeper understanding of foundational aspects and has attracted a great deal of attention – starting from the early days of quantum theory. While it is often highlighted… [Read more…]
August 11, 2011
Observing quantum effects such as superpositions and entanglement in macroscopic systems requires not only a system that is well protected against environmental decoherence, but also sufficient measurement precision. Motivated by recent experiments, we study the effects of coarse-graining in photon number measurements on the observability of micro-macro entanglement that is created by greatly amplifying one… [Read more…]
August 10, 2011
Two independent groups of physicists have made important breakthroughs in the control of quantum computers based on trapped ions. Instead of controlling quantum bits (qubits) using multiple laser beams, the teams have used microwave sources, which are much easier to control and integrate within quantum circuits. The work could lead to practical quantum computers that… [Read more…]
August 9, 2011
When information is transmitted in microscopic systems, such as single photons (single light particles) or atoms, its information carriers obey quantum rather than classical physics. This o ers many new possibilities for information processing, since it is possible to invent novel information processes prevented by classical physics. Quantum cryptography is the most mature technology in the… [Read more…]
August 9, 2011
Scott Aaronson One might think that, once we know something is computable, how efficiently it can be computed is a practical question with little further philosophical importance. In this essay, I offer a detailed case that one would be wrong. In particular, I argue that computational complexity theory—the field that studies the resources (such as… [Read more…]
August 8, 2011
The Many Worlds Wiener Sausage is a very simple model that shows how the apparent non-locality in the infamous Einstein-Podolsky-Rosen paradox can arise simply by the world splitting into parallel universes. It can be understood by advanced high school students. But we saw that although it is a many worldsmodel, it is not a quantum world! Today we will make the model… [Read more…]
August 8, 2011
A theory of reality beyond Einstein’s universe is taking shape – and a mysterious cosmic signal could soon fill in the blanks IT WASN’T so long ago we thought space and time were the absolute and unchanging scaffolding of the universe. Then along came Albert Einstein, who showed that different observers can disagree about the… [Read more…]
August 7, 2011
No one likes a know-it-all but we expect to be able to catch them out: someone who acts like they know everything but doesn’t can always be tripped up with a well-chosen question. Can’t they? Not so. New research in quantum physics has shown that a quantum know-it-all could lack information about a subject as… [Read more…]
July 29, 2011
This paper describes a scheme, through which the quantum information as well as the structural information of a time-reversal invariant system can be teleported over a distance. I show that my teleportation scheme can be viewed as a form of reversible purification process by repeated interactions with an auxiliary quantum system…. Read more: http://arxiv.org/ftp/arxiv/papers
July 25, 2011
A 1959 Physical Review paper claimed that an electric or magnetic field could influence quantum particles even though the particles never experienced the field directly. In classical electromagnetism there is no other way to influence a particle besides direct contact with the fields. Even though quantum mechanics was well-established by then, the idea met with widespread skepticism.… [Read more…]
July 19, 2011
We know how to use the “rules” of quantum physics to build lasers, microchips, and nuclear power plants, but when students question the rules themselves, the best answer we can give is often, “The world just happens to be that way.” Yet why are individual outcomes in quantum measurements random? What is the origin of… [Read more…]
July 19, 2011
An ambitious experiment to make a glass sphere exist in two places at once could provide the most sensitive test of quantum theory yet. The experiment will place a sphere containing millions of atoms – making it larger than many viruses – into a superposition of states in different places, say researchers in Europe. Physicists… [Read more…]
physicsworld newscientist.com NASA dailygalaxy technologyreview science2.0
May 21, 2012
0