Finite-frequency fluctuation-response bounds for open quantum systems
Abstract
We derive a finite-frequency fluctuation-response inequality for Markovian open quantum systems in an input-output setting. For any downstream measurement of the emitted field, the measured lock-in response-to-noise matrix is bounded by the output-field quantum Fisher information rate. For dissipative amplitude modulation with vacuum inputs, this information rate is further bounded by a frequency-independent signal-channel activity, which reduces for kinetic modulation to the stationary channel fluxes. The result is detector-facing but unraveling-independent: it applies after choosing a measurement record, while the information ceiling is set by the quantum field before any detection scheme or trajectory representation is selected. We formulate the bound for multiple signal channels and real finite-frequency quadratures, and illustrate it with a single-sided cavity, resonance fluorescence, and a truncated Kerr-parametric cat resonator.
Versions
Related
- Fluctuation--Response Relation in Finite-Size Noisy Coupled Phase Oscillators
- Formal Fluctuation-Response Relations for Non-Stationary Systems: The Dynamic Conjugate Variable
- A Study of Fluctuation Growths of Observables in Open Quantum Systems
- Information-Geometric Representation of Upper Bounds on Fluctuation Growth in Open Quantum Systems
- Finite-Frequency Boson-Number Bounds Across the Quantum Rabi Transition
BibTeX
@misc{gu2026finitefrequency,
title = {{Finite-frequency fluctuation-response bounds for open quantum systems}},
author = {Jie Gu and Kangqiao Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.03340},
eprint = {2605.03340},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.03340},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Finite-frequency fluctuation-response bounds for open quantum systems
AU - Jie Gu
AU - Kangqiao Liu
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2605.03340
UR - https://arxiv.org/abs/2605.03340
AB - We derive a finite-frequency fluctuation-response inequality for Markovian open quantum systems in an input-output setting. For any downstream measurement of the emitted field, the measured lock-in response-to-noise matrix is bounded by the output-field quantum Fisher information rate. For dissipative amplitude modulation with vacuum inputs, this information rate is further bounded by a frequency-independent signal-channel activity, which reduces for kinetic modulation to the stationary channel fluxes. The result is detector-facing but unraveling-independent: it applies after choosing a measurement record, while the information ceiling is set by the quantum field before any detection scheme or trajectory representation is selected. We formulate the bound for multiple signal channels and real finite-frequency quadratures, and illustrate it with a single-sided cavity, resonance fluorescence, and a truncated Kerr-parametric cat resonator.
ER -