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Imaging quantum entanglement
September 24, 2007An international team including scientists from the London Centre for Nanotechnology (LCN) today publishes findings in the journal 'Proceedings of the National Academy of Sciences' (PNAS) demonstrating the dramatic effects of quantum mechanics in a simple magnet. The importance of the work lies in establishing how a conventional tool of material science - neutron beams produced at particle accelerators and nuclear reactors - can be used to produce images of the ghostly entangled states of the quantum world.
At the nano scale, magnetism arises from atoms behaving like little magnets called 'spins'. In ferromagnets - the kind that stick to fridge doors - all of these atomic magnets point in the same direction. In antiferromagnets, the spins were thought to spontaneously align themselves opposite to the adjacent spins, leaving the material magnetically neutral overall. The new research shows that this picture is not correct because it ignores the uncertainties of quantum mechanics. In particular, at odds with everyday intuition, the quantum-mechanical physical laws which operate on the nano-scale allow a spin to simultaneously point both up and down. At the same time, two spins can be linked such that even though it is impossible to know the direction of either by itself, they will always point in opposite directions - in which case they are 'entangled'.
With their discovery, the researchers demonstrate that neutrons can detect entanglement, the key resource for quantum computing.
One of the lead authors of the work, Professor Des McMorrow from the LCN, comments: "When we embarked on this work, I think it is fair to say that none of us were expecting to see such gigantic effects produced by quantum entanglement in the material we were studying. We were following a hunch that this material might yield something important and we had the good sense to pursue it."
The researchers' next steps will be to pursue the implications for high temperature superconductors, materials carrying electrical currents with no heating and which bear remarkable similarities to the insulating antiferromagnets they have studied, and the design of quantum computers.
University College London
One of the lead authors of the work, Professor Des McMorrow from the LCN, comments: "When we embarked on this work, I think it is fair to say that none of us were expecting to see such gigantic effects produced by quantum entanglement in the material we were studying. We were following a hunch that this material might yield something important and we had the good sense to pursue it."
The researchers' next steps will be to pursue the implications for high temperature superconductors, materials carrying electrical currents with no heating and which bear remarkable similarities to the insulating antiferromagnets they have studied, and the design of quantum computers.
University College London
Quantum Mechanics Current Events and Quantum Mechanics News RSSNIST demonstrates 'universal' programmable quantum processor
Physicists at the National Institute of Standards and Technology (NIST) have demonstrated the first "universal" programmable quantum information processor able to run any program allowed by quantum mechanics-the rules governing the submicroscopic world-using two quantum bits (qubits) of information.
First Bose-Einstein condensation of strontium
In an international first, scientists from the Institute of Quantum Optics and Quantum Information (IQOQI) produced a Bose-Einstein condensate of the alkaline-earth element strontium, thus narrowly winning an international competition between many first-rate scientific groups
Quantum gas microscope offers glimpse of quirky ultracold atoms
Physicists at Harvard University have created a quantum gas microscope that can be used to observe single atoms at temperatures so low the particles follow the rules of quantum mechanics, behaving in bizarre ways.
Quantum computer chips now 1 step closer to reality
In the quest for smaller, faster computer chips, researchers are increasingly turning to quantum mechanics -- the exotic physics of the small. The problem: the manufacturing techniques required to make quantum devices have been equally exotic. That is, until now.
Field experiment on a robust hierarchical metropolitan quantum cryptography network
Key Laboratory of Quantum Information (CAS), University of Science and Technology of China has recently demonstrated a metropolitan Quantum Cryptography Network (QCN) for Government Administration in Wuhu, China. Because of its scientific significance and social impact, the project is reported in Volume 54, Issue 17 (September, 2009) of the Chinese Science Bulletin authored by Fang-xing Xu et al.
UA scientists discover quantum fingerprints of chaos
Chaotic behavior is the rule, not the exception, in the world we experience through our senses, the world governed by the laws of classical physics.
Building a better qubit
Exploiting quantum mechanics for transmitting information is a tantalizing possibility because it promises secure, high speed communications.
Physicists at UC Santa Barbara make discovery in quantum mechanics
Physicists at UC Santa Barbara have made an important advance in quantum mechanics using a superconducting electrical circuit. The finding is reported in this week's issue of the journal Nature.
A tiny, tunable well of light, and a string theorist's toolbox
Photonics, the science of using photons to carry information, promises to continue improving a wide variety of technologies, from computing to high-speed communication.
Atoms don't dance the 'bose nova'
Hanns-Christoph Naegerl's research group has investigated how ultracold quantum gases behave in lower spatial dimensions. They successfully realized an exotic state, where, due to the laws of quantum mechanics, atoms align along a one-dimensional structure.
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