An ultra-compact deterministic source of maximally entangled photon pairs

TL;DR

This paper introduces an ultra-compact, highly efficient source of entangled photon pairs using GaAs quantum dots integrated with micro-optics, suitable for industrial applications and capable of high-rate, high-purity photon emission.

Contribution

The work presents a novel, miniaturized entangled photon source with integrated micro-optics and demonstrates high performance in photon rate, purity, and entanglement quality at cryogenic temperatures.

Findings

Achieved single photon emission rate of 392 kHz at 76 MHz pump rate.

Demonstrated near-maximal entanglement with negativity of 0.96.

System exhibits 99.2% purity in photon emission.

Abstract

We present an ultra-compact source of maximally entangled on-demand photon pairs. Our results are based on coupling of single GaAs quantum dots that are embedded in monolithic micro-lenses to a single-mode fiber with directly attached to 3D-printed micro-optics (NA of 0.6) inside a cryogenic environment. This approach, which is geared towards future integration into industrial environments, yields state-of-the-art entangled photon pair creation performance while retaining flexibility and adjustability required for long-term operation of such a device - all while dramatically reducing the overall system footprint. We demonstrate near diffraction-limited performance and hyperspectral imaging utilizing a 3D-printed micro-objective with a full width at half maximum resolution limit of 604(16) nm when operating the system at a cryogenic temperature of 3.8 K. Furthermore, we prove that this system can be used to achieve single photon emission rates of 392(20) kHz at a 76 MHz pump rate and purities of 99.2(5) % using two-photon resonant excitation. Utilizing the exciton-biexciton emission cascade available in GaAs quantum dots under resonant excitation, near maximally entangled photon pairs with peak entanglement negatives 2n of 0.96(2) in a 4 ps time window, and 0.81(1) when averaged over one exciton lifetime, are demonstrated.