Numerically exact path integral simulation of nonequilibrium quantum transport and dissipation

TL;DR

This paper introduces a numerically exact iterative method for simulating nonequilibrium quantum transport and dissipation, effectively avoiding the sign problem and applicable to complex quantum systems driven out of equilibrium.

Contribution

The authors develop a new iterative approach that circumvents the sign problem in nonequilibrium quantum simulations, enabling accurate real-time dynamics analysis.

Findings

Successfully applied to two-level system and Anderson model

Achieves convergence without the sign problem

Results agree with other established techniques

Abstract

We develop an iterative, numerically exact approach for the treatment of nonequilibrium quantum transport and dissipation problems that avoids the real-time sign problem associated with standard Monte Carlo techniques. The method requires a well-defined decorrelation time of the non-local influence functional for proper convergence to the exact limit. Since finite decorrelation times may arise either from temperature or from a voltage drop at zero temperature, the approach is well suited for the description of the real-time dynamics of single-molecule devices and quantum dots driven to a steady-state via interaction with two or more electron leads. We numerically investigate two non-trivial models: the evolution of the nonequilibrium population of a two-level system coupled to two electronic reservoirs, and quantum transport in the nonequilibrium Anderson model. For the latter case, two distinct formulations are described. Results are compared to those obtained by other techniques.