Nonselective generalized measurements as a resource for quantum thermal machines in a double quantum dot

TL;DR

This paper explores how nonselective generalized measurements can power quantum thermal machines in a double quantum dot system, revealing new operational modes and optimization strategies.

Contribution

It introduces a measurement-driven thermodynamic cycle in a double quantum dot with tunneling, expanding understanding beyond simple qubit models.

Findings

System can operate as heat engine, accelerator, heater, or refrigerator.

Tunneling reshapes operational boundaries and enables refrigeration modes.

Performance depends on temperature, detuning, and tunneling amplitude.

Abstract

We investigated quantum thermal machines powered by sequential nonselective generalized measurements, taking a double quantum dot with coherent interdot tunneling as a working substance. In this platform, the competition between detuning and tunneling hybridizes the localized states and modifies the energetic response of the cycle, allowing us to analyze measurement-driven thermodynamics beyond simple diagonal qubit models. We formulate a three-stroke cycle composed of thermalization with a single reservoir and two generalized measurement channels, and derive the corresponding internal-energy and entropy variations in order to identify the operational regimes of the device. Depending on the measurement parameters, the system can operate as a heat engine, accelerator, heater, or refrigerator. We show that the introduction of tunneling not only reshapes the boundaries between these modes, but also generates refrigeration configurations that are absent in the purely detuned model. In addition, the performance maps reveal that temperature, detuning, and tunneling amplitude jointly control the most favorable regions for work extraction and cooling. Our results demonstrate that coherent interdot coupling acts as an important resource for optimizing measurement-powered quantum thermal machines and highlight double quantum dots as a promising setting for experimentally relevant implementations of measurement-assisted thermodynamic devices.