Testing Kubo formula on a nonlinear quantum conductor driven far from equilibrium via power exchanges

Fuente: arXiv
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Autores principales: Iftikhar, Zubair, Müller, Jonas, Mukharsky, Yuri, Joyez, Philippe, Roche, Patrice, Altimiras, Carles
Formato: Preprint
Publicado: 2025
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author Iftikhar, Zubair
Müller, Jonas
Mukharsky, Yuri
Joyez, Philippe
Roche, Patrice
Altimiras, Carles
author_facet Iftikhar, Zubair
Müller, Jonas
Mukharsky, Yuri
Joyez, Philippe
Roche, Patrice
Altimiras, Carles
contents We present an experimental test of Kubo formula performed on a nonlinear quantum conductor, a Superconductor-Insulator-Superconductor tunnel junction, driven far from equilibrium by a DC voltage bias. We implement the proposal of Lesovik and Loosen [1] and demonstrate experimentally that it is possible to extract both the emission and absorption noise of the conductor by measuring the power it exchanges with a linear detection circuit whose occupation is tuned close to vacuum levels. We then compare their difference to the real part of the admittance which is independently measured by coherent reflectometry, finding that Kubo formula holds within experimental accuracy. Last, we show theoretically that the spectral density of power exchanged between a quantum conductor and its linear detection circuit follows a Lesovik and Loosen like formula, even in the presence of strong detection back-action. This result applies as long as the conductor acts as a current source for the detection circuit and the detection circuit is not singular.
format Preprint
id arxiv_https___arxiv_org_abs_2503_11478
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Testing Kubo formula on a nonlinear quantum conductor driven far from equilibrium via power exchanges
Iftikhar, Zubair
Müller, Jonas
Mukharsky, Yuri
Joyez, Philippe
Roche, Patrice
Altimiras, Carles
Mesoscale and Nanoscale Physics
We present an experimental test of Kubo formula performed on a nonlinear quantum conductor, a Superconductor-Insulator-Superconductor tunnel junction, driven far from equilibrium by a DC voltage bias. We implement the proposal of Lesovik and Loosen [1] and demonstrate experimentally that it is possible to extract both the emission and absorption noise of the conductor by measuring the power it exchanges with a linear detection circuit whose occupation is tuned close to vacuum levels. We then compare their difference to the real part of the admittance which is independently measured by coherent reflectometry, finding that Kubo formula holds within experimental accuracy. Last, we show theoretically that the spectral density of power exchanged between a quantum conductor and its linear detection circuit follows a Lesovik and Loosen like formula, even in the presence of strong detection back-action. This result applies as long as the conductor acts as a current source for the detection circuit and the detection circuit is not singular.
title Testing Kubo formula on a nonlinear quantum conductor driven far from equilibrium via power exchanges
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2503.11478