Induced superconductivity in high mobility two dimensional electron gas in GaAs heterostructures

TL;DR

This paper demonstrates induced superconductivity in high mobility GaAs 2DEG with transparent NbN contacts, enabling exploration of superconductivity and correlated states at high magnetic fields, advancing quantum physics research.

Contribution

It develops transparent superconducting contacts to GaAs 2DEG and observes supercurrent over several microns, a significant step for studying non-Abelian states and Majorana fermions.

Findings

Supercurrent observed across 0.6 μm of 2DEG.

High critical magnetic fields (>16 Tesla) achieved.

Potential for exploring non-Abelian states in GaAs 2DEG.

Abstract

Introduction of a Josephson field effect transistor (JoFET) concept sparked active research on proximity effects in semiconductors. Induced superconductivity and electrostatic control of critical current has been demonstrated in two-dimensional gases in InAs, graphene and topological insulators, and in one-dimensional systems including quantum spin Hall edges. Recently, interest in superconductor-semiconductor interfaces was renewed by the search for Majorana fermions, which were predicted to reside at the interface. More exotic non-Abelian excitations, such as parafermions (fractional Majorana fermions) or Fibonacci fermions may be formed when fractional quantum Hall edge states interface with superconductivity. In this paper we develop transparent superconducting contacts to high mobility two-dimensional electron gas (2DEG) in GaAs and demonstrate induced superconductivity across several microns. Supercurrent in a ballistic junction has been observed across 0.6 $\mu$m of 2DEG, a regime previously achieved only in point contacts but essential to the formation of well separated non-Abelian states. High critical fields ($>16$ Tesla) in NbN contacts enables investigation of a long-sought regime of an interplay between superconductivity and strongly correlated states in a 2DEG at high magnetic fields.