title: RETRACTED: Real-time quantum feedback control of atomic spin-squeezing.
abstract: 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.
authors.affiliation: Physics and Control and Dynamical Systems, California Institute of Technology, Pasadena, CA 91125, USA. jgeremia@caltech.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Geremia
authors.forename: John K
authors.initials: JK
authors.lastname: Stockton
authors.forename: Hideo
authors.initials: H
authors.lastname: Mabuchi