Polarized Single-Photon Emission from an Anisotropic Dirac Cavity

Polarized single-photon sources (SPSs) are valuable for quantum information applications and can be implemented by exploiting an elliptical or birefringent cavity that provide polarization-selective Purcell enhancement. However, current designs suffer from similar quality (Q) factors of split cavity modes, requiring both high Purcell factor and substantial mode splitting for ideal polarization performance. Here, we report a low-Purcell anisotropic Dirac cavity that supports orthogonally polarized modes with significantly distinct Q factors (1032 vs 98). When coupled to a single quantum dot, this cavity enables single-photon emission [g^{(2)}(0)=0.028] with >99% degree of linear polarization (DoLP). The high DoLP is tolerant to emission wavelength, originating from suppression of competing radiative channels. Lifetime measurements demonstrate a 1.72-fold enhancement at cavity resonance and a 3.47-fold inhibition in a photonic band gap. Additionally, the anisotropic Dirac cavity exhibits vertical directionality with simulated collection efficiency up to 92.7%. Our results offer a novel strategy toward ideal solid-state polarized SPSs.