Quantum Fisher Information of Driven-Dissipative Systems from Keldysh Path Integrals
Abstract
Driven-dissipative many-body quantum systems can be exploited in quantum enhanced sensing protocols. Here, non-classical correlations may allow one to reach a measurement precision that surpasses the standard quantum limit. The relevant figure of merit for assessing such quantum advantage is the quantum Fisher information (QFI). In a many-body setting its computation is challenging as it requires knowledge of the full system-environment state. Here we make use of a field-theoretical approach, which is particularly well suited for systems with many degrees of freedom. In particular, we exploit that the QFI can be linked to a Keldysh path-integral. This route leads to a semiclassical expression of the QFI, which is obtained through a controlled expansion in the so-called quantum fields. We benchmark the framework on three systems of increasing complexity: the driven-dissipative harmonic oscillator, the boundary time crystal - which becomes semiclassical at large system sizes - and a two-dimensional array of collectively emitting atoms. We assess in which parameter regimes the semiclassical description holds and gives access to system sizes beyond the reach of exact methods.
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BibTeX
@misc{jirasek2026quantum,
title = {{Quantum Fisher Information of Driven-Dissipative Systems from Keldysh Path Integrals}},
author = {Malik Jirasek and Igor Lesanovsky and Viktoria Noel},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.26462},
eprint = {2609.26462},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26462},
}
RIS
TY - UNPB
TI - Quantum Fisher Information of Driven-Dissipative Systems from Keldysh Path Integrals
AU - Malik Jirasek
AU - Igor Lesanovsky
AU - Viktoria Noel
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2609.26462
UR - https://arxiv.org/abs/2609.26462
AB - Driven-dissipative many-body quantum systems can be exploited in quantum enhanced sensing protocols. Here, non-classical correlations may allow one to reach a measurement precision that surpasses the standard quantum limit. The relevant figure of merit for assessing such quantum advantage is the quantum Fisher information (QFI). In a many-body setting its computation is challenging as it requires knowledge of the full system-environment state. Here we make use of a field-theoretical approach, which is particularly well suited for systems with many degrees of freedom. In particular, we exploit that the QFI can be linked to a Keldysh path-integral. This route leads to a semiclassical expression of the QFI, which is obtained through a controlled expansion in the so-called quantum fields. We benchmark the framework on three systems of increasing complexity: the driven-dissipative harmonic oscillator, the boundary time crystal - which becomes semiclassical at large system sizes - and a two-dimensional array of collectively emitting atoms. We assess in which parameter regimes the semiclassical description holds and gives access to system sizes beyond the reach of exact methods.
ER -