Quantum Trajectory Thermodynamics with Discrete Feedback Control

TL;DR

This paper develops a quantum trajectory framework to analyze thermodynamics in open quantum systems with feedback control, revealing quantum-specific effects like negative information gain and rare events.

Contribution

It introduces quantum generalized Jarzynski equalities incorporating quantum coherence and measurement backaction, with potential experimental tests in superconducting qubits.

Findings

Quantum versions of Jarzynski equalities are derived.

Quantum coherence leads to negative information gain.

Experimental schemes for testing are proposed.

Abstract

We employ the quantum jump trajectory approach to construct a systematic framework to study the thermodynamics at the trajectory level in a nonequilibrium open quantum system under discrete feedback control. Within this framework, we derive quantum versions of the generalized Jarzynski equalities, which are demonstrated in an isolated pseudospin system and a coherently driven two-level open quantum system. Due to quantum coherence and measurement backaction, a fundamental distinction from the classical generalized Jarzynski equalities emerges in the quantum versions, which is characterized by a large negative information gain reflecting genuinely quantum rare events. A possible experimental scheme to test our findings in superconducting qubits is discussed.