Non-Markovian control of qubit thermodynamics by frequent quantum measurements

TL;DR

This paper investigates how rapid quantum nondemolition measurements on qubits in contact with a thermal bath can control their thermodynamic properties, leading to non-standard behavior and fast state manipulation.

Contribution

It introduces a framework for controlling qubit thermodynamics through frequent measurements, revealing non-Markovian effects that differ from classical thermodynamics.

Findings

Measurement rate determines entropy and temperature independently of standard thermodynamics.

Frequent measurements enable rapid heating, cooling, and entropy reduction of qubits.

Control occurs faster than thermal equilibration time.

Abstract

We explore the effects of frequent, impulsive quantum nondemolition measurements of the energy of two-level systems (TLS), alias qubits, in contact with a thermal bath. The resulting entropy and temperature of both the system and the bath are found to be completely determined by the measurement rate, and unrelated to what is expected by standard thermodynamical rules that hold for Markovian baths. These anomalies allow for very fast control of heating, cooling and state-purification (entropy reduction) of qubits, much sooner than their thermal equilibration time.