Making rare events typical in Markovian open quantum systems

TL;DR

This paper demonstrates how rare dynamical fluctuations in Markovian open quantum systems can be engineered and controlled by relating them to typical realizations of alternative systems, enabling on-demand manipulation of quantum behavior.

Contribution

It introduces a method to generate rare quantum dynamics from typical dynamics of an auxiliary system, facilitating control over quantum fluctuations.

Findings

Established a correspondence between rare and typical quantum trajectories.

Applied the method to a three-qubit system showing dynamical phase crossover.

Showed potential for engineering quantum systems with desired fluctuation properties.

Abstract

Large dynamical fluctuations - atypical realizations of the dynamics sustained over long periods of time - can play a fundamental role in determining the properties of collective behavior of both classical and quantum non-equilibrium systems. Rare dynamical fluctuations, however, occur with a probability that often decays exponentially in their time extent, thus making them difficult to be directly observed and exploited in experiments. Here, using methods from dynamical large deviations, we explain how rare dynamics of a given (Markovian) open quantum system can always be obtained from the typical realizations of an alternative (also Markovian) system. The correspondence between these two sets of realizations can be used to engineer and control open quantum systems with a desired statistics "on demand". We illustrate these ideas by studying the photon-emission behaviour of a three-qubit system which displays a sharp dynamical crossover between active and inactive dynamical phases.