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】
Free