Polarization Entangled Photons from Semiconductor Quantum Dots

Abstract

Semiconductor quantum dots are among the most promising candidates for the deterministic generation of polarization entangled photon pairs. In this chapter we review the most recent progress on this topic. First, we recall the basic concepts of polarization entangled photon qubits, the biexciton cascade process and exciton fine structure splitting in single quantum dots. The experimental techniques for controlling the fine structure splitting, which are critical for the generation of photon pairs with a high fidelity to the symmetric Bell state, are briefly discussed. A main focus is given to the recently developed anisotropic strain engineering technique, which has been used to fabricate an entangled light-emitting-diode with high yield and fast triggering speed, and an entangled photon source with wavelength tunability. Experimental progress on improving the collection efficiency of the entangled photon sources are also mentioned. We envision that, with the remarkable achievements in the field, the entanglement distribution, the hybrid interfacing with atoms, the telecom band emissions, and the on-chip integration will be realized soon with quantum dot based polarization entangled photon sources.