Dynamics of quantum coherences at strong coupling to a heat bath

Abstract

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 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.

10 pages, 11 figures

References in corpus (11)

• The numerical renormalization group method for quantum impurity systems
• Real-time path integral approach to nonequilibrium many-body quantum system
• Multiple energy scales at a quantum critical point
• Equilibrium and non-equilibrium dynamics of the sub-ohmic spin-boson model
• Mesoscopic Spin-Boson Models of Trapped Ions
• Entanglement and Criticality in Quantum Impurity Systems
• Reservoir engineering and dynamical phase transitions in optomechanical arrays
• Persistence of coherent quantum dynamics at strong dissipation
• Non-perturbative stochastic method for driven spin-boson model
• Dissipation due to two-level systems in nano-mechanical devices
• Spin-boson dynamics beyond conventional perturbation theories

Cited by in corpus (7)

• Energy exchange in driven open quantum systems at strong coupling
• Variational dynamics of the sub-Ohmic spin-boson model on the basis of multiple Davydov ${\mathrm{D}}_1$ states
• Dynamics of the spin-boson model: the effect of bath initial conditions
• Bipartite entanglement dynamics of two-level systems in sub-Ohmic reservoirs
• Non-equilibrium boundary driven quantum systems: models, methods and properties
• Separation of relaxation timescales via strong system-bath coupling: Dissipative three-level system as a case study
• Transient Dynamical Phase Diagram of the Spin-Boson Model at Finite Temperature