Dynamics of quantum coherences at strong coupling to a heat bath

Article

关键词: REDUCED DENSITY-MATRICES;    TENSOR PROPAGATOR;    2-LEVEL SYSTEMS;    2-STATE SYSTEM;    TIME EVOLUTION;    DECOHERENCE;    DISSIPATION;   

DOI  :  10.1103/PhysRevB.87.134301

来源: SCIE

【 摘 要 】

The standard approach for path-integral Monte Carlo simulations of open quantum systems is extended as an efficient tool to monitor the time evolution of coherences (off-diagonal elements of the reduced density matrix) also for strong coupling to environments. Specific simulations are performed for two-level systems embedded in Ohmic and sub-Ohmic reservoirs in the domains of coherent and incoherent dynamics of the polarization. In the latter regime, the notorious difficulty to access the long-time regime is overcome by combining simulations on moderate time scales with iteratively calculated initial densities. This allows us to extract relaxation rates for sub-Ohmic environments at finite temperatures and over a broad range of couplings and to compare them to analytical predictions. The time evolution of the von Neumann entropy provides insight into the quantum phase transition at thermal equilibrium from a delocalized to a localized state at zero temperature. DOI:10.1103/PhysRevB.87.134301

【 授权许可】

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