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(Phys.org) -- When two photons simultaneously enter two input ports of a beam splitter, their paths interfere destructively, which causes the photons to simultaneously exit the beam splitter through the same output port. Because this quantum interference effect changes the input into a different output, it could have applications in quantum information processing. But whereas the two photons are usually identical in experiments demonstrating this effect, a new study has demonstrated that quantum interference can also occur between two photons with different frequencies, giving researchers an additional degree of control.

Physicists of the group of Prof. Anton Zeilinger at the Institute for Quantum Optics and Quantum Information (IQOQI), the University of Vienna, and the Vienna Center for Quantum Science and Technology (VCQ) have, for the first time, demonstrated in an experiment that the decision whether two particles were in an entangled or in a separable quantum state can be made even after these particles have been measured and may no longer exist. Their results will be published this week in the journal Nature Physics.

Experimental physicist Rainer Blatt from the Institute for Quantum Optics and Quantum Information (IQOQI) in Innsbruck, Austria, will receive the Stern-Gerlach Medal of the German Physical Society. The medal will be presented by Germany's Research Minister Anette Schavan in Berlin on Tuesday 27 March 2012.

Tourists who drift aimlessly during a sightseeing tour are moving randomly - just like electrons that move from one atom to the next. To obtain a better understanding of these random motions it is often useful to reduce their complexity. Physicists do this by simulating random walks

(PhysOrg.com) -- Quantum correlations have well-known advantages in areas such as communication, computing, and cryptography, and recently physicists have discovered that they may help players competing in zero-sum games, as well. In a new study, researchers have found that a game player who uses an appropriate quantum strategy can greatly increase their chances of winning compared with using a classical strategy.

Fumio Futami at Tamagawa University, Quantum ICT Research Institute, announced the world first transmission of the stream cipher by Yuen 2000 protocol (Y-00) at the bit rate of 40 Gbit/sec over 120 km.

(PhysOrg.com) -- If a practical quantum computer is ever to be realized, conventional electronic devices will have to interface with the delicate quantum systems such as atoms or ions in traps or wisps of magnetism near superconducting sensors.

Physicists take a perverse pleasure in playing with the strangeness of the quantum world. That's how they have managed to entangle minuscule objects such as photons

(PhysOrg.com) -- MIT researcher Scott Aaronson has certainly riled the physics community with his offer this past Friday, of $100,000 to anyone who can prove that scaled-up quantum computing is impossible. His original reason for doing so was, as he describes in his blog, due to adding his two cents to an argument between skeptic Gil Kalai and researcher Aram Harrow about assumptions regarding the Quantum Fault-Tolerance Theorem, on another blog, where he argued that refuting the idea of scalable quantum computing would amount to more than just taking apart the QFT Theorem; it would he suggested, mean coming up with a new version of physical reality.

(PhysOrg.com) -- During the past few years, CERN physicist Dragan Hajdukovic has been investigating what he thinks may be a widely overlooked part of the cosmos: the quantum vacuum. He suggests that the quantum vacuum has a gravitational charge stemming from the gravitational repulsion of virtual particles and antiparticles. Previously, he has theoretically shown that this repulsive gravity can explain several observations, including effects usually attributed to dark matter.

(PhysOrg.com) -- During the past few years, CERN physicist Dragan Hajdukovic has been investigating what he thinks may be a widely overlooked part of the cosmos: the quantum vacuum. He suggests that the quantum vacuum has a gravitational charge stemming from the gravitational repulsion of virtual particles and antiparticles. Previously, he has theoretically shown that this repulsive gravity can explain several observations, including effects usually attributed to dark matter.

Editor's Note: Reprinted from How the Hippies Saved Physics: Science, Counterculture, and the Quantum Revival by David Kaiser. Copyright (c) 2011 by David Kaiser.

(PhysOrg.com) -- Physicists at the Max Planck Institute of Quantum Optics have measured the propagation velocity of quantum signals in a many-body system.

Researchers have succeeded in combining the power of quantum computing with the security of quantum cryptography and have shown that perfectly secure cloud computing can be achieved using the principles of quantum mechanics. They have performed an experimental demonstration of quantum computation in which the input, the data processing, and the output remain unknown to the quantum computer.

Heisenberg'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.