Adaptive variational open quantum system dynamics*

The theory of open quantum systems studies the properties of a small quantum system in contact with a large environment. Because perfect isolation of a quantum system is unrealistic, in practice, any quantum system should be treated as an open system. Thus, developing quantum algorithms that can efficiently simulate open quantum systems is of vital importance in searching for potential applications of quantum computers. Here we present an adaptive variational quantum algorithm to simulate the open quantum system dynamics. The method is based on variationally solving either the vectorized Lindblad master equation or the stochastic Schrodinger equation unraveled from the Lindblad master equation. The ansatz is adaptively built at every time step by minimizing McLachlan's distance, which is a measure of the simulation accuracy. We demonstrate the efficacy of the algorithm by benchmarking it against the exact solver for solving the quantum annealing dynamics.