Quantum transport in a normal metal/odd-frequency superconductor junction

TL;DR

This paper investigates the unique quantum transport signatures of odd-frequency superconductors in normal metal junctions, proposing conductance measurements as a way to identify such exotic states.

Contribution

It provides a theoretical framework using Eliashberg and Keldysh formalisms to distinguish odd-frequency from conventional superconductors through tunneling conductance.

Findings

Distinct electrical conductance behavior in odd-frequency superconductors

Unique thermal conductance signatures for odd-frequency states

Potential experimental probes for identifying odd-frequency superconductivity

Abstract

Recent experimental results indicate the possible realization of a bulk odd-frequency superconducting state in the compounds CeCu$_2$Si$_2$, and CeRhIn$_5$. Motivated by this, we present a study of the quantum transport properties of a normal metal/odd-frequency superconductor junctions in a search for probes to unveil the odd-frequency symmetry. From the Eliashberg equations, we perform a quasiclassical approximation to account for the transport formalism of an odd-frequency superconductor with the Keldysh formalism. Specifically, we consider the tunneling charge conductance and tunneling thermal conductance. We find qualitatively distinct behaviour in the odd-frequency case as compared to the conventional even-frequency case, in both the electrical and thermal current. This serves as a useful tool to identify the possible existence of a bulk odd-frequency superconducting state.