Proximity effect in a two dimensional electron gas probed with a lateral quantum dot

TL;DR

This study investigates the proximity effect in a 2D electron gas using a lateral quantum dot within a Nb-InGaAs-Nb Josephson junction, revealing insights into quasiparticle transport and energy gap modulation.

Contribution

It demonstrates the use of cotunneling spectroscopy to probe the induced energy gap and validates a resonant tunneling model for such hybrid nanodevices.

Findings

Good qualitative agreement with the Anderson impurity model.

Feasibility of top-gated 2D electron gas nanodevices with superconductors.

Direct measurement of the induced energy gap in the 2D electron gas.

Abstract

We report low-temperature transport measurements performed on a planar Nb-InGaAs-Nb proximity Josephson junction hosting a gate-defined lateral quantum dot in the weak-link. We first study quasiparticle and Josephson transport through the open junction, when all gates are grounded. When the quantum dot is defined in the normal region by electrostatic depletion, cotunneling spectroscopy allows us to directly probe the energy gap induced in the two dimensional electron gas. Our data show good qualitative agreement with a model describing resonant tunneling through an Anderson impurity connected to superconducting electrodes. These results demonstrate the feasibility of top-gated nanodevices based on a two-dimensional electron gas coupled to a superconductor.