Active Quantum Particles from Engineered Dissipation

TL;DR

This paper introduces models of quantum active particles driven by engineered dissipation, demonstrating key active motion features and exploring quantum effects, with potential experimental implementations.

Contribution

It develops quantum models of active particles from engineered dissipation, unifying classical active behaviors with quantum dynamics and boundary sensitivity.

Findings

Models exhibit crossover from diffusive to active-diffusive behavior.

Strong boundary sensitivity due to Liouville skin effect.

Potential realizations in superconducting circuits or cold gases.

Abstract

We introduce and characterize different models for an active quantum particle where activity arises from engineered dissipation-- specifically, from a suitably coupled nonequilibrium environment. These include a model of a particle moving on a lattice with coherent and dissipative hopping, as well as quantum generalizations of well-studied models of active behavior, such as the active Ornstein-Uhlenbeck process, run-and-tumble dynamics, and the active Brownian particle. Despite the different microscopic mechanisms at play, we show that all these models display key features of active motion. Notably, we observe a crossover from diffusive to active-diffusive behavior at long times, leading to an effective P\'eclet number, as well as a strong sensitivity to boundary conditions which, in our open quantum system context, arises from the Liouville skin effect. We discuss the role of quantum fluctuations and experimental realizations with superconducting circuits or cold gases, closing with perspectives for many-body effects in quantum active matter.