John Donahue has joined us for graduate studies from the University of Windsor. Welcome John!
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Kurt Schreiter has been award NSERC’s top fellowship for pursuing his doctoral studies. Congratulations Kurt! From NSERC’s website: The Vanier CGS program aims to attract and retain world-class doctoral students by supporting students who demonstrate both leadership skills and a high standard of scholarly achievement in graduate studies in the social sciences and humanities, natural sciences and engineering, and health sciences.
The Dean of Science Award is given in recognition of outstanding performance in the Master of Science program. One certificate will normally be awarded annually to a master’s student from each department in the Science faculty in recognition of creative research as presented in the student’s thesis. Mike Mazurek has joined the group as an MSc student. Laura Richards and Logan Wright have joined us for the summer as NSERC Undergraduate Student Research Assistants. Welcome All!
Abstract: We present and experimentally demonstrate a communication protocol that employs shared entanglement to reduce errors when sending a bit over a particular noisy classical channel. Specifically, it is shown that given a single use of this channel, one can transmit a bit with higher success probability when the sender and receiver share entanglement compared to the best possible strategy when they do not. The experiment is realized using polarization-entangled photon pairs, whose quantum correlations play a critical role in both the encoding and decoding of the classical message. Experimentally, we find that a bit can be successfully transmitted with probability 0.891±0.002, which is close to the theoretical maximum of (2+2-1/2)/3≈0.902 and is significantly above the optimal classical strategy, which yields 5/6≈0.833.
Update April 1, 2011: A Search and Discovery article, Entanglement enhances classical communication, by Johanna Miller was published in Physics Today…today.
One-way quantum computation proceeds by sequentially measuring individual spins in an entangled many-spin resource state. It remains a challenge, however, to efficiently produce such resources. Is it possible to reduce the task of their production to simply cooling a quantum many-body system to its ground state? Cluster states, the canonical resource for one-way quantum computing, do not naturally occur as ground states of physical systems, leading to a significant effort to identify alternatives that do appear as ground states in spin lattices. An appealing candidate is a valence-bond solid state described by Affleck, Kennedy, Lieb and Tasaki (AKLT). It is the unique, gapped ground state for a two-body Hamiltonian on a spin-1 chain, and can be used as a resource for one-way quantum computing. Here, we experimentally generate a photonic AKLT state and use it to implement single-qubit quantum logic gates. Our paper, Experimental Bound Entanglement?, by Jonathan Lavoie, Rainer Kaltenbaek, Marco Piani, and Kevin Resch was published in Nature Physics. This work comments on a claim of experimental bound entanglement published late last year in the same journal. Concluding paragraph of our comment: Undistillability is the one property that makes an entangled state bound. Amselem and Bourennane’s results fail to show undistillability and thus they cannot claim to have produced bound entanglement. See here for the original paper and the authors’ reply to our comment. See also our recently published results [J. Lavoie et al. Physical Review Letters 105, 130501 (2010)] on experimental bound entanglement where, for the first time, we definitively show both properties of bound entanglement: entanglement and undistillability. Our paper Minimum-error discrimination of entangled quantum states by Yang Lu, Nick Coish, Rainer Kaltenbaek, Deny Hamel, Sarah Croke, and Kevin Resch was published today in Physical Review A. Continue reading Entangled state discrimination results in PRA Krister Shalm has joined IQC as a post-doctoral fellow to work with the Quantum Optics and Quantum Information group and the Quantum Photonics Laboratory. Krister has just finished his PhD (or will have by next week) with Aephraim Steinberg at the University of Toronto. He brings with him a CIFAR Junior Fellowship. Welcome Krister! Kent Fisher has joined the QOQI group for his MSc research. Kent finished his BSc at the University of Guelph last spring and was awarded an NSERC CGS to fund his studies. Welcome Kent! Experimental Bound Entanglement in a Four-Photon State by Jonathan Lavoie, Rainer Kaltenbaek, Marco Piani, and Kevin Resch was published today in Physical Review Letters. Bound entanglement is central to many exciting theoretical results in quantum information processing, but has thus far not been experimentally realized. In this work, we consider a one-parameter family of four-qubit Smolin states. We experimentally produce these states in the polarization of four optical photons produced from parametric down-conversion. Within a range of the parameter, we show that our states are entangled and undistillable, and thus bound entangled. Using these bound-entangled states we demonstrate entanglement unlocking. |
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