Suppression of Decoherence by Periodic Forcing |
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Authors: | Volker Bach Walter de Siqueira Pedra Marco Merkli Israel Michael Sigal |
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Institution: | 1. Institut für Analysis und Algebra, TU?Braunschweig, 38106?, Braunschweig, Germany 2. Instituto de Fisica - Departamento de Fisica Matematica, Universidade de Sao Paulo, Caixa Postal 66318, Sao Paulo, SP?, 05314-970, Brasil 3. Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John’s, Newfoundland, NL?, A1C 5S7, Canada 4. Department of Mathematics, University of Toronto, Toronto, ON?, M5S 2E4, Canada
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Abstract: | We consider a finite-dimensional quantum system coupled to a thermal reservoir and subject to a time-periodic, energy conserving forcing. We show that, if a certain dynamical decoupling condition is fulfilled, then the periodic forcing counteracts the decoherence induced by the reservoir: for small system–reservoir coupling $\lambda $ and small forcing period $T$ , the system dynamics is approximated by an energy conserving and non-dissipative dynamics, which preserves coherences. For times up to order $(\lambda T)^{-1}$ , the difference between the true and approximated dynamics is of size $\lambda +T$ . Our approach is rigorous and combines Floquet and spectral deformation theory. We illustrate our results on the spin-fermion model and recover previously known, heuristically obtained results. |
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