Ultra-efficient generation of time-energy entangled photon pairs in an InGaP photonic crystal cavity

Abstract

The typical approaches to generate heralded single photons rely on parametric processes, with the advantage of generating highly entangled states at the price of a random pair emission. To overcome this limit, degenerate spontaneous Four-Wave-Mixing is a reliable technique which combines two pump photons into a pair of signal and idler photons via Kerr nonlinear optical effect. By exploiting the intrinsic small confinement volume and thermally tuning the resonances of a 20 μm-long Photonic Crystal cavity, we efficiently generate time-energy entangled photon pairs and heralded single photons at a large maximum on-chip rate of 22 MHz, using 36 μW of pump power. We measure time-energy entanglement with net visibility up to 96.6 % using 1 second integration time constant. Our measurements demonstrate the viability of Photonic Crystal cavities to act as an alternative and efficient photon pair source for quantum photonics.

Integrated Reconfigurable Photon-Pair Source Based on High-Q Nonlinear Chalcogenide Glass Microring Resonators

“…Normalizing the PGR is normalized to the spectrum bandwidth of 173.32 MHz; the given spectral brightness is as high as 4.28 × 10 8 pairs s –1 mW –2 GHz –1 . This PGR value assisted by the high Q factor is comparable to the microcavity-based quantum sources in platforms such as SOI and InP with larger χ (3) but a relatively small Q factor, but more than 2 orders of magnitude lower than those with comparative Q factor in other platforms including AlGaAs with larger χ (3) , InGaP with smaller nonlinear volume, and LiNbO 3 using second-order nonlinearity (see Table S1 in Supporting Information for details). Moreover, the large bandgap ( E g = 2.39 eV) of the Ge 25 Sb 10 S 65 material prevents saturation phenomenon induced by two-photon absorption at the telecom band that is inevitably encountered in InP or SOI platforms with strong χ (3) nonlinearities. , …”