# Quantum transport under AC drive from the leads : A Quantum Master Equation approach

## TL;DR

This paper develops a comprehensive quantum master equation framework to analyze the dynamics of driven open quantum systems, enabling calculation of physical observables like current and revealing effects such as resonance.

## Contribution

It introduces a general, transparent method based on Redfield equations for non-interacting particles under periodic driving, applicable to various geometries and particle types.

## Key findings

- The theory accurately predicts current dynamics in driven quantum dot systems.
- Time-dependent currents can surpass average currents, aiding experimental detection.
- The approach is validated against exact numerical simulations.

## Abstract

Evaluating the time-dependent dynamics of driven open quantum systems is relevant for a theoretical description of many systems, including molecular junctions, quantum dots, cavity-QED experiments, cold atoms experiments and more. Here, we formulate a rigorous microscopic theory of an out-of-equilibrium open quantum system of non-interacting particles on a lattice weakly coupled to multiple baths and driven by periodically varying thermodynamic parameters like temperature and chemical potential of the bath. The particles can be either bosonic or fermionic and the lattice can be of any dimension and geometry. Based on Redfield quantum master equation under Born-Markov approximation, we derive a complete set of linear differential equations for equal time two-point correlation functions from which various physical observables, for example, current, can be calculated. Various interesting physical effects, such as resonance, can be directly read-off from the equations. Thus, our theory is quite general gives quite transparent and easy-to-calculate results. We validate our theory by comparing with exact numerical simulations. We apply our method to a generic open quantum system, namely a double-quantum dot coupled to leads with modulating chemical potentials. Two most important experimentally relevant insights from this are : (i) time-dependent measurements of current for symmetric oscillating voltages (with zero instantaneous voltage bias) can point to the degree of asymmetry in the system, and (ii) under certain conditions, time-dependent currents can exceed time-averaged currents by several orders of magnitude, and can therefore be detected even when the average current is below the measurement threshold.