Superconducting photonics and development of light emitting diodes based on new concept

The authors have proposed a photon-emitting LED (light-emitting diode) combined with superconducting electrodes, which is expected to be an on-demand entangled photon pair source. The main mechanism is based on the coherent spatial extension of the Cooper-pair states to the photon emitting layer, which is expected to enhance the oscillator strength of the radiative recombination processes by the Cooper-pair involvement in the recombination processes. In this paper, the preliminary operation is demonstrated with InGaAs quantum well (QW) LEDs. About 20-times enhancement of the electroluminescence (EL) was observed under the low-injection current regime. This is the demonstration of the improved internal quantum efficiency (QE) under the low internal QE operation of the LED. The enhancement of the radiative recombination processes with the superconducting (SC) effect is also demonstrated by the lifetime measurements under the operation with high internal QE.