Single-photon source emitting single-photon with controllable circular polarization direction

A single-photon source emitting light with a controllable circular polarization direction comprising:

• a semiconductor substrate;
• a pillar structure located above the semiconductor substrate and comprising a semiconductor single-quantum-dot structure;
• a spin injection layer located above the pillar structure and configured to inject a spin-polarized carrier into the semiconductor single-quantum-dot structure;
• a first electrode and a second electrode respectively connected to the spin injection layer and the semiconductor substrate and configured to apply a pulsed voltage between the spin injection layer and the semiconductor substrate, so as to inject a spin-polarized single-carrier into the semiconductor single-quantum-dot structure from the spin injection layer,
• wherein in response to the injected spin-polarized single-carrier, a single-photon is emitted from the single-quantum-dot in the semiconductor single-quantum-dot structure with the circular polarization direction determined by the spin direction of the spin-polarized single-carrier.