Quantum Work Extraction via Conditional Spatial Displacements
Abstract
We propose a protocol for extracting work from a coherent quantum battery state by exploiting measurement-assisted feedback mediated by a continuous-variable pointer. The scheme relies on the unitary operator U = exp(−i k t Ĥ ⊗ P̂/ℏ), which generates entanglement between the battery's energy eigenstates and the position of an auxiliary pointer. A subsequent projective measurement of the pointer's position conditionally prepares the battery in a pure state from which work can be extracted via a feedback unitary. We analyze the protocol for a two-level quantum battery and a Gaussian pointer, computing the conditional states and the corresponding daemonic ergotropy. For the pure initial state considered, we find that the daemonic ergotropy equals the standard ergotropy for all interaction strengths, demonstrating that the measurement-assisted feedback recovers the full extractable work that would otherwise become inaccessible due to entanglement with the pointer when its degrees of freedom are traced out. The protocol thus provides a physically transparent realization of a quantum Maxwell demon, where the pointer acts as a quantum measurement ancilla whose position becomes correlated with the battery's energy. The scheme is amenable to experimental implementation in trapped-ion systems, and it contributes to the ongoing efforts to understand the role of quantum coherence and measurement in thermodynamics.
Related
- Work Extraction Across a Thermodynamic Hierarchy in Quantum Many-Body Systems
- Controlled Dark-State Energy Storage and Work Extraction in V-Type Quantum Batteries
- Quantum work extraction from partial information and with finite resources
- Unbounded Work Extraction and Zero Work Fluctuations in a Super-Carnot Otto Information Engine
- Dynamics of Work Extraction in Multipartite Atomic Systems: Role of Correlations and Relative Entropy
BibTeX
@misc{celik2026quantum,
title = {{Quantum Work Extraction via Conditional Spatial Displacements}},
author = {Necati Çelik},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.24425},
eprint = {2609.24425},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.24425},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Quantum Work Extraction via Conditional Spatial Displacements
AU - Necati Çelik
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.24425
UR - https://arxiv.org/abs/2609.24425
AB - We propose a protocol for extracting work from a coherent quantum battery state by exploiting measurement-assisted feedback mediated by a continuous-variable pointer. The scheme relies on the unitary operator U = exp(−i k t Ĥ ⊗ P̂/ℏ), which generates entanglement between the battery's energy eigenstates and the position of an auxiliary pointer. A subsequent projective measurement of the pointer's position conditionally prepares the battery in a pure state from which work can be extracted via a feedback unitary. We analyze the protocol for a two-level quantum battery and a Gaussian pointer, computing the conditional states and the corresponding daemonic ergotropy. For the pure initial state considered, we find that the daemonic ergotropy equals the standard ergotropy for all interaction strengths, demonstrating that the measurement-assisted feedback recovers the full extractable work that would otherwise become inaccessible due to entanglement with the pointer when its degrees of freedom are traced out. The protocol thus provides a physically transparent realization of a quantum Maxwell demon, where the pointer acts as a quantum measurement ancilla whose position becomes correlated with the battery's energy. The scheme is amenable to experimental implementation in trapped-ion systems, and it contributes to the ongoing efforts to understand the role of quantum coherence and measurement in thermodynamics.
ER -