Signatures of odd-frequency pairing in the Josephson junction current noise

Abstract

Odd-frequency (odd−ω) electron pair correlations naturally appear at the interface between BCS superconductors and other materials. The detection of odd−ω pairs, which are necessarily nonlocal in time, is still an open problem. The main reason is that they do not contribute to static measurements described by time-local correlation functions. Therefore, dynamical measurements, which depend on nonlocal time correlations, are suitable for detecting these pairs. In this work, we study the signatures of odd−ω pairs in the supercurrent noise through a weak link between two superconductors at different superconducting phases. We show that the finite-frequency current noise can be decomposed into three different contributions coming from even-frequency (even−ω), odd−ω pair amplitudes, and electron-hole correlation functions. Odd−ω pairing, which is interlead (between electrons at different sides of the junction), provides a positive contribution to the noise, becoming maximal at a superconducting phase difference of π. In contrast, intralead even−ω pair amplitude tends to reduce the noise, except for a region close to π controlled by the transmission of the junction.

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