Experimental test of Kubo relation on a non-linear quantum conductor from energy exchanges

Speaker Carles Altemiras (SPEC, Université Paris-Saclay, UMR3680 CEA – CNRS)

Abstract:

We present an experimental test of Kubo formula on a non-linear quantum conductor, a Superconducting-Insulator-Superconducting tunnel junction, driven far from equilibrium by a dc voltage bias. Following the proposal of Lesovik & Loosen, we first demonstrate it is possible to extract both emission and absorption noise of the conductor by measuring the power it exchanges with a linear detection circuit whose population 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 relation holds within experimental accuracy.