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Main Authors: Kokalj, Žan, Favalli, Tommaso, Trombettoni, Andrea
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2511.22439
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author Kokalj, Žan
Favalli, Tommaso
Trombettoni, Andrea
author_facet Kokalj, Žan
Favalli, Tommaso
Trombettoni, Andrea
contents Studying the performance of a quantum interferometer coupled to an external environment is a problem of conceptual and practical importance. If we consider a quantum interferometer featuring Heisenberg-limited sensitivity, then a typical result is that introducing coupling with the environment degrades the sensitivity to the shot-noise limit. Here we argue that this result crucially depends on whether the interferometer-environment coupling term is subject (or not) to the so-called Kac rescaling that restores extensivity, i.e., whether the coupling Hamiltonian is extensive or not. We present results of the Lindblad equation in the presence and absence of Kac rescaling of the coupling constant. Our results show that for a linear coupling and a harmonic model of the environment, often used in modeling of a quantum interferometer coupled with an environment, the Heisenberg-limited sensitivity may be restored after the Kac rescaling. This result points out the need and the importance to characterize the (model of the) environment of the interferometer at hand.
format Preprint
id arxiv_https___arxiv_org_abs_2511_22439
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effect of Energy Extensivity on the Performance of Open Quantum Interferometers
Kokalj, Žan
Favalli, Tommaso
Trombettoni, Andrea
Quantum Physics
Studying the performance of a quantum interferometer coupled to an external environment is a problem of conceptual and practical importance. If we consider a quantum interferometer featuring Heisenberg-limited sensitivity, then a typical result is that introducing coupling with the environment degrades the sensitivity to the shot-noise limit. Here we argue that this result crucially depends on whether the interferometer-environment coupling term is subject (or not) to the so-called Kac rescaling that restores extensivity, i.e., whether the coupling Hamiltonian is extensive or not. We present results of the Lindblad equation in the presence and absence of Kac rescaling of the coupling constant. Our results show that for a linear coupling and a harmonic model of the environment, often used in modeling of a quantum interferometer coupled with an environment, the Heisenberg-limited sensitivity may be restored after the Kac rescaling. This result points out the need and the importance to characterize the (model of the) environment of the interferometer at hand.
title Effect of Energy Extensivity on the Performance of Open Quantum Interferometers
topic Quantum Physics
url https://arxiv.org/abs/2511.22439