Supercurrent and Conductance Quantization in a Superconducting Quantum Point Contact

TL;DR

This paper investigates quantized supercurrent and conductance in a superconducting quantum point contact, demonstrating that each transport mode contributes simultaneously to both supercurrent and conductance, with stepwise changes as a function of gate voltage.

Contribution

It provides experimental evidence of simultaneous quantization of supercurrent and conductance in a SQPC, highlighting the role of transport modes in both phenomena.

Findings

Supercurrent and conductance change stepwise with gate voltage.

First transport mode contributes to both supercurrent and conductance.

Steps in supercurrent and conductance occur at the same gate voltages.

Abstract

We study the quantization of the supercurrent and conductance of a superconducting quantum point contact (SQPC) in a superconductor-two dimensional electrongas-superconductor (S-2DEG-S) Josephson junction with a split gate. The supercurrent and the conductance values change stepwise as a function of the gate voltage. We observe the onset of the first transport mode contributing both to the supercurrent and the conductance of the SQPC. Furthermore the steps in the supercurrent and the conductance appear at the same gate voltage values. This shows, that each transport mode in the SQPC contributes both to the normal state conductance and to the supercurrent.