Luminescence and Squeezing of a Superconducting Light Emitting Diode

TL;DR

This paper explores how superconductivity in a semiconductor p-n junction enhances light emission, induces entangled photon pairs, and enables electrical control of light squeezing, with potential for low-threshold lasing.

Contribution

It demonstrates that superconducting leads significantly boost electroluminescence, generate entangled photons, and reduce lasing thresholds in a semiconductor diode.

Findings

Superconductivity increases electroluminescence in specific frequency ranges.

Cooper pair tunneling creates an additional luminescence peak.

Superconducting coherence enables electrical control of light squeezing.

Abstract

We investigate a semiconductor $p$-$n$ junction in contact with superconducting leads that is operated under forward bias as a light-emitting diode. The presence of superconductivity results in a significant increase of the electroluminescence in a certain frequency window. We demonstrate that the tunneling of Cooper pairs induces an additional luminescence peak on resonance. There is a transfer of superconducting to photonic coherence which results in the emission of entangled photon pairs and squeezing of the fluctuations in the quadrature amplitudes of the emitted light. The squeezing angle can be electrically manipulated by changing the relative phase of the order parameters in the superconductors. We finally derive the conditions for lasing in the system and show that the laser threshold is reduced due to superconductivity. This shows how macroscopic coherence of a superconductor can be used to control the properties of light.