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This article has been retracted

Science 9 April 2004:
Vol. 304. no. 5668, pp. 270 - 273
DOI: 10.1126/science.1095374
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Reports

Real-Time Quantum Feedback Control of Atomic Spin-Squeezing

JM Geremia,* John K. Stockton, Hideo Mabuchi

Real-time feedback performed during a quantum nondemolition measurement of atomic spin-angular momentum allowed us to influence the quantum statistics of the measurement outcome. We showed that it is possible to harness measurement backaction as a form of actuation in quantum control, and thus we describe a valuable tool for quantum information science. Our feedback-mediated procedure generates spin-squeezing, for which the reduction in quantum uncertainty and resulting atomic entanglement are not conditioned on the measurement outcome.

Physics and Control and Dynamical Systems, California Institute of Technology, Pasadena, CA 91125, USA.

* To whom correspondence should be addressed. E-mail: jgeremia{at}caltech.edu

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