Feedback-stabilization of an arbitrary pure state of a two-level atom

By Jin Wang, Howard M. Wiseman. 2000

138 citations recorded by the source corpus.

Unit-efficiency homodyne detection of the resonance fluorescence of a two-level atom collapses the quantum state of the atom to a stochastically moving point on the Bloch sphere. Recently, Hofmann, Mahler, and Hess [Phys. Rev. A 57, 4877 (1998)] showed that by making part of the coherent driving proportional to the homodyne photocurrent one can stabilize the state to any point on the bottom-half of the sphere. Here we reanalyze their proposal using the technique of stochastic master equations, allowing their results to be generalized in two ways. First, we show that any point on the upper- or lower-half, but not the equator, of the sphere may be stabilized. Second, we consider nonunit-efficiency detection, and quantify the effectiveness of the feedback by calculating the maximal purity obtainable in any particular direction in Bloch space.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics, Biophysics

View Paper: https://www.semanticscholar.org/paper/4f216c3e91eb429beb6f498d4c98223f4ae55c85

Citations in the corpus

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