Phys.org: Phys.org news tagged with: uncertainty principle
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en-usPhys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.'Compressive sensing' provides new approach to measuring a quantum system(Phys.org) —In quantum physics, momentum and position are an example of conjugate variables. This means they are connected by Heisenberg's Uncertainty Principle, which says that both quantities cannot be simultaneously measured precisely. Recently, researchers have been developing novel techniques, such as "weak measurement," to measure both at the same time. Now University of Rochester physicists have shown that a technique called compressive sensing also offers a way to measure both variables at the same time, without violating the Uncertainty Principle.
http://phys.org/news323089137.html
PhysicsFri, 27 Jun 2014 11:59:07 EDTnews323089137Tricking the uncertainty principle(Phys.org) —Caltech researchers have found a way to make measurements that go beyond the limits imposed by quantum physics.
http://phys.org/news319396501.html
PhysicsThu, 15 May 2014 18:15:22 EDTnews319396501Proving uncertainty: First rigorous formulation supporting Heisenberg's famous 1927 principleNearly 90 years after Werner Heisenberg pioneered his uncertainty principle, a group of researchers from three countries has provided substantial new insight into this fundamental tenet of quantum physics with the first rigorous formulation supporting the uncertainty principle as Heisenberg envisioned it.
http://phys.org/news317991201.html
PhysicsTue, 29 Apr 2014 11:53:38 EDTnews317991201A bound on the natural width of the Higgs bosonCMS has improved the constraints on the Higgs width, a fundamental property of this unique new particle, by more than two orders of magnitude.
http://phys.org/news315640594.html
PhysicsWed, 02 Apr 2014 06:56:47 EDTnews315640594Physicists propose explanation for metals behaving badly(Phys.org) —One of the defining properties of metals is that, the hotter the metal, the worse it conducts electricity. But while most metals obey this inverse relationship between temperature and conductivity in a straightforward way as predicted by theory, other metals do not. At high temperatures, the electrons in these so-called "bad metals" ought to violate Heisenberg's uncertainty principle so that the metals no longer conduct electricity. However, experiments have shown that these metals do continue to conduct electricity at high temperatures. The failure of current models to explain this behavior is a central problem in condensed matter physics, a field that deals with understanding the physical properties of materials.
http://phys.org/news315221564.html
PhysicsFri, 28 Mar 2014 12:00:01 EDTnews315221564Researchers use squeezed light to enhance photonic force microscopy(Phys.org) —A team of researchers working in Australia has used "squeezed light" to enhance the sharpness of images produced using photonic force microscopy. In their paper published in Physical Review Letters, the team describes how they applied a property of quantum mechanics to microscopy to offer resolution enhancement of up to 14 percent.
http://phys.org/news312114325.html
PhysicsThu, 20 Feb 2014 11:10:02 EDTnews312114325Researchers use quantum entanglement to improve differential interference contrast microscopy(Phys.org)—A team of researchers with members from Hokkaido and Osaka Universities in Japan has used quantum entanglement of photons to improve image results created using differential interference contrast microscopy. In their paper published in Nature Communications, the team describes how they used entangled photons to enhance an image taken of an etched (to a depth of just 17 nanometers) letter "Q" on a glass plate, and how much improvement was observed.
http://phys.org/news311324177.html
PhysicsTue, 11 Feb 2014 08:30:01 EDTnews311324177Research team challenges the limits of famous quantum principle(Phys.org) —A team of physicists is challenging the very limits of Heisenberg's famous uncertainty principle by measuring quantum particles with unprecedented accuracy.
http://phys.org/news310806836.html
PhysicsWed, 05 Feb 2014 07:30:05 EDTnews310806836Teleportation just got easier—but not for you, unfortunatelyThanks to two studies published in Nature last Thursday, the chance of successful teleportation has considerably increased. Which is a good thing, right?
http://phys.org/news296290882.html
PhysicsWed, 21 Aug 2013 08:01:37 EDTnews296290882'Listening' to black holes form with gravity wavesNew technology that breaks the quantum measurement barrier has been developed to detect the gravity waves first predicted by Einstein in 1916.
http://phys.org/news295863849.html
PhysicsFri, 16 Aug 2013 10:10:02 EDTnews295863849Uncertainty revisited: Novel tradeoffs in quantum measurement(Phys.org) —There is, so to speak, uncertainty about uncertainty – that is, over the interpretation of how Heisenberg's uncertainty principle describes the extent of disturbance to one observable when measuring another. More specifically, the confusion is between the fact that, as Heisenberg first intuited, the measurement of one observable on a quantum state necessarily disturbs another incompatible observable, and the fact that on the other hand the indeterminacy of the outcomes when either one or the other observable is measured is bounded. Recently, Dr. Cyril Branciard at The University of Queensland precisely quantified the former by showing how it is possible to approximate the joint measurement of two observables, albeit with the introduction of errors with respect to the ideal measurement of each. Moreover, the scientist characterized the disturbance of an observable induced by the approximate measurement of another one, and derived a stronger error-disturbance relation for this scenario.
http://phys.org/news288948339.html
PhysicsTue, 28 May 2013 09:00:01 EDTnews288948339Hydrogen atoms under the magnifying glassTo 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
PhysicsWed, 22 May 2013 08:50:03 EDTnews288430300Physicists successfully transmit secure quantum code through atmosphere from aircraft to ground station(Phys.org) —Can worldwide communication ever be fully secure? Quantum physicists believe they can provide secret keys using quantum cryptography via satellite. Unlike communication based on classical bits, quantum cryptography employs the quantum states of single light quanta (photons) for the exchange of data. Heisenberg's uncertainty principle limits the precision with which the position and momentum of a quantum particle can be determined simultaneously, but can also be exploited for secure information transfer. Like its classical counterpart, quantum cryptography requires a shared key with which the parties encode and decode messages. However, quantum mechanical phenomena guarantee the security of quantum key distribution. Because quantum states are fragile, interception of the key by an eavesdropper will alter the behavior properties of the particles, and thus becomes detectable.
http://phys.org/news284199561.html
PhysicsWed, 03 Apr 2013 09:19:40 EDTnews284199561Getting around the 'uncertainty principle': Physicists make first direct measurements of polarization states of lightResearchers at the University of Rochester and the University of Ottawa have applied a recently developed technique to directly measure for the first time the polarization states of light. Their work both overcomes some important challenges of Heisenberg's famous Uncertainty Principle and also is applicable to qubits, the building blocks of quantum information theory.
http://phys.org/news281520818.html
PhysicsSun, 03 Mar 2013 13:00:21 EDTnews281520818Light particles illuminate the vacuumResearchers from the Finnish Aalto University and the Technical Research Centre of Finland succeeded in showing experimentally that vacuum has properties not previously observed. According to the laws of quantum mechanics, it is a state with abundant potentials. Vacuum contains momentarily appearing and disappearing virtual pairs, which can be converted into detectable light particles.
http://phys.org/news281093264.html
PhysicsTue, 26 Feb 2013 09:27:54 EDTnews281093264Curves in spacetime violate Heisenberg's uncertainty principle(Phys.org)—If an object traveling through spacetime can loop back in time in a certain way, then its trajectory can allow a pair of its components to be measured with perfect accuracy, violating Heisenberg's uncertainty principle. This new finding involves a particular trajectory called an open timelike curve (OTC), which is a special case of a closed timelike curve (CTC), a theoretical concept that has previously provoked controversy because it raises the possibility of traveling backwards in time.
http://phys.org/news280404720.html
PhysicsTue, 19 Feb 2013 09:00:01 EDTnews280404720Researchers demonstrate Heisenberg uncertainty principle at macro level(Phys.org)—Physicists working at the University of Colorado have succeeded in demonstrating one of the major tenets of quantum mechanics—namely the Heisenberg uncertainty principle—at the macro level. In their paper published in the journal Science, the team describes how a small but still visible drum they built in their lab, outfitted with mirrors, a laser and a detector, demonstrated that it was not possible to measure a photon's position and momentum simultaneously.
http://phys.org/news280128966.html
PhysicsFri, 15 Feb 2013 07:30:01 EDTnews280128966Human hearing beats the Fourier uncertainty principle(Phys.org)—For the first time, physicists have found that humans can discriminate a sound's frequency (related to a note's pitch) and timing (whether a note comes before or after another note) more than 10 times better than the limit imposed by the Fourier uncertainty principle. Not surprisingly, some of the subjects with the best listening precision were musicians, but even non-musicians could exceed the uncertainty limit. The results rule out the majority of auditory processing brain algorithms that have been proposed, since only a few models can match this impressive human performance.
http://phys.org/news279188691.html
PhysicsMon, 04 Feb 2013 09:00:01 EDTnews279188691Revealing quantum flow(Phys.org)—UK-based physicist Ole Steuernagel from the University of Hertfordshire, alongside Dimitris Kakofengitis and Georg Ritter, have found that a new powerful tool they call 'Wigner flow' is the quantum analogue of phase space flow.
http://phys.org/news275899138.html
PhysicsFri, 28 Dec 2012 06:39:24 EDTnews275899138Physicists extend entanglement in Einstein experiment(Phys.org)—Using a photon fission process, physicists have split a single photon into a pair of daughter photons and then split one of the daughter photons into a pair of granddaughters to create a total of three photons. All three photons, the scientists showed, share quantum correlations between their energies (corresponding to their momentums) and between their emission times (corresponding to their positions). The study marks the first experimental demonstration of energy-time entanglement of three or more individual particles, building on the original two-particle version proposed by Einstein, Podolsky, and Rosen (EPR) 77 years ago.
http://phys.org/news274001995.html
PhysicsThu, 06 Dec 2012 09:10:02 EDTnews274001995More certainty on uncertainty's quantum mechanical roleScientists who study the ultra-small world of atoms know it is impossible to make certain simultaneous measurements, for example finding out both the location and momentum of an electron, with an arbitrarily high level of precision. Because measurements disturb the system, increased certainty in the first measurement leads to increased uncertainty in the second. The mathematics of this unintuitive concept – a hallmark of quantum mechanics – were first formulated by the famous physicist Werner Heisenberg at the beginning of the 20th century and became known as the Heisenberg Uncertainty Principle. Heisenberg and other scientists later generalized the equations to capture an intrinsic uncertainty in the properties of quantum systems, regardless of measurements, but the uncertainty principle is sometimes still loosely applied to Heisenberg's original measurement-disturbance relationship. Now researchers from the University of Toronto have gathered the most direct experimental evidence that Heisenberg's original formulation is wrong.
http://phys.org/news268569309.html
PhysicsThu, 04 Oct 2012 11:35:20 EDTnews268569309Researchers develop fast, sensitive nanophotonic motion sensor developed for silicon microdevices(Phys.org)—Using a microscopic optical sensor that can be batch-fabricated on a silicon chip at low cost, researchers from the NIST Center for Nanoscale Science and Technology have measured the mechanical motion between two nanofabricated structures with a precision close to the fundamental limit imposed by quantum mechanics.
http://phys.org/news267341434.html
PhysicsThu, 20 Sep 2012 06:30:44 EDTnews267341434Physicists experimentally demonstrate one-way quantum steering(Phys.org)—When Einstein described the interaction between two distant objects as "spooky interaction at a distance," he was referring to the quantum phenomenon called steering. Steering can occur in strongly entangled systems and implies a direction between the two parties involved, while entanglement without steering generally has no direction. In 1992, physicists experimentally demonstrated steering in both directions – that is, both parties could steer each other. Now for the first time, physicists have demonstrated steering in one direction only, a feat that gives new insight into the quantum world and that could have applications in quantum information.
http://phys.org/news267093733.html
PhysicsMon, 17 Sep 2012 12:40:01 EDTnews267093733Scientists cast doubt on renowned uncertainty principleWerner Heisenberg's uncertainty principle, formulated by the theoretical physicist in 1927, is one of the cornerstones of quantum mechanics. In its most familiar form, it says that it is impossible to measure anything without disturbing it. For instance, any attempt to measure a particle's position must randomly change its speed.
http://phys.org/news266242688.html
PhysicsFri, 07 Sep 2012 13:18:21 EDTnews266242688Scientists score one more victory over uncertainty in quantum physics measurements(PhysOrg.com) -- Most people attempt to reduce the little uncertainties of life by carrying umbrellas on cloudy days, purchasing automobile insurance or hiring inspectors to evaluate homes they might consider purchasing. For scientists, reducing uncertainty is a no less important goal, though in the weird realm of quantum physics, the term has a more specific meaning.
http://phys.org/news249480424.html
PhysicsSun, 26 Feb 2012 13:00:01 EDTnews249480424Are you certain, Mr. Heisenberg? New measurements deepen understanding of quantum uncertaintyHeisenberg's Uncertainty principle is arguably one of the most famous foundations of quantum physics. It says that not all properties of a quantum particle can be measured with unlimited accuracy. Until now, this has often been justified by the notion that every measurement necessarily has to disturb the quantum particle, which distorts the results of any further measurements. This, however, turns out to be an oversimplification. In neutron experiments carried out by professor Yuji Hasegawa and his team at Vienna University of Technology, different sources of quantum uncertainty can now be distinguished, validating theoretical results by collaborators from Japan. The influence of the measurement on the quantum system is not always the reason for uncertainty. Heisenberg's arguments for the uncertainty principle have to be revisited – the uncertainty principle itself however remains valid. The results have now been published in the journal Nature Physics.
http://phys.org/news246019189.html
PhysicsTue, 17 Jan 2012 10:40:39 EDTnews246019189New fundamental limitation restricts position accuracy of quantum objects(PhysOrg.com) -- Although the uncertainty principle is probably the most well-known example of a fundamental limitation of measurement precision in quantum mechanics, it is not the only one. In fact, every physical system is characterized by a number of variables that do not change their values as the system evolves over time; such variables are called conserved quantities and they are said to obey a conservation law. The fact that some quantities cannot change their values suggests that there might be restrictions on the possible ways in which a measurement device can interact with a quantum object and extract information from it.
http://phys.org/news220521739.html
PhysicsMon, 28 Mar 2011 09:02:41 EDTnews220521739Heisenberg Uncertainty Principle sets limits on Einstein's 'spooky action at a distance,' new research findsResearchers have uncovered a fundamental link between the two defining properties of quantum physics. Stephanie Wehner of Singapore's Centre for Quantum Technologies and the National University of Singapore and Jonathan Oppenheim of the United Kingdom's University of Cambridge published their work today in the latest edition of the journal Science.
http://phys.org/news209312379.html
PhysicsThu, 18 Nov 2010 14:19:58 EDTnews209312379More accurate than Heisenberg allows? Uncertainty in the presence of a quantum memoryQuantum cryptography is the safest way to encrypt data. It utilizes the fact that transmitted information can only be measured with a strictly limited degree of precision. Scientists at Ludwig-Maximilians-University in Munich and ETH Zurich have now discovered how the use of a quantum memory affects this uncertainty.
http://phys.org/news199443918.html
PhysicsTue, 27 Jul 2010 10:30:01 EDTnews199443918Physicists detect entanglement of one photon shared among four locationsScientists at the California Institute of Technology (Caltech) have developed an efficient method to detect entanglement shared among multiple parts of an optical system. They show how entanglement, in the form of beams of light simultaneously propagating along four distinct paths, can be detected with a surprisingly small number of measurements. Entanglement is an essential resource in quantum information science, which is the study of advanced computation and communication based on the laws of quantum mechanics.
http://phys.org/news161026685.html
PhysicsFri, 08 May 2009 18:38:40 EDTnews161026685