A spintronic source of circularly polarized single photons

TL;DR

This paper introduces a novel spintronic single photon source that emits highly circularly polarized light, with polarization controlled by magnetic fields, suitable for quantum cryptography applications.

Contribution

It demonstrates a spintronic quantum dot device capable of emitting highly circularly polarized single photons with tunable helicity via magnetic fields.

Findings

Achieved 83% polarization at 2T and 96% at 6T magnetic fields.

Proved the emitted light is antibunched, confirming single-photon emission.

Potential use in quantum cryptography for encoding quantum states.

Abstract

We present a spintronic single photon source which emits circularly polarized light, where the helicity is determined by an applied magnetic field. Photons are emitted from an InGaAs quantum dot inside an electrically operated spin light-emitting diode, which comprises the diluted magnetic semiconductor ZnMnSe. The circular polarization degree of the emitted light is high, reaching 83% at an applied magnetic field of 2T and 96% at 6 T. Autocorrelation traces recorded in pulsed operation mode prove the emitted light to be antibunched. The two circular polarization states could be used for representing quantum states |0> and |1> in quantum cryptography implementations.