Angular-dependent Andreev reflection on a polaritonic superfluid

TL;DR

This paper analytically investigates angle-dependent Andreev reflection phenomena at a polariton superfluid interface, revealing conditions for reflection, transmission, and surface modes through theoretical formulas and numerical simulations.

Contribution

It introduces analytical formulas for Andreev reflection at a polariton superfluid interface and confirms findings with numerical simulations under realistic conditions.

Findings

Identified limit angles and energies for Andreev reflection and transmission.

Derived analytical expressions for reflection and transmission amplitudes.

Confirmed surface mode formation at high energies and angles.

Abstract

We study analytically an analog of the Andreev reflection at a normal-superfluid interface. The polariton gapped superfluid region is achieved by quasi-resonant optical pumping. The interacting polaritons are described with the driven-dissipative Gross-Pitaevskii equation. We find analytical formulas for the angles and amplitudes of the reflected and transmitted particles. There are limit angles and energies, above which Andreev reflection/transmission cannot be observed anymore and where the Andreev wave becomes a surface mode, exponentially localized on the interface. These properties are confirmed by solving numerically the Gross-Pitaevskii equation in simulations reproducing realistic experimental conditions.