A natural strategy for realizing practical single-photon devices is to adapt current semiconductor light emitters and detectors. I discuss progress towards a single-photon technology based upon integrating self-organised quantum dots into conventional optoelectronic devices.
Epitaxial quantum dots formed by III-V compound semiconductors are excellent sources of nonclassical photons, creating single photons and entangled multi-photon states on demand.Their semiconductor nature allows for a straightforward combination with mature integrated photonic technologies, leading to novel functional devices at the single-photon level.Integrating a quantum dot into a carefully engineered photonic cavity enables control of the radiative decay rate using the Purcell effect and the realization of photon-photon nonlinear gates.In this review, we introduce the basis of epitaxial quantum dots and discuss their applications as non-classical light sources.We highlight two interfaces-one between flying photons and the quantum-dot dipole, and the other between the photons and the spin.We summarize the recent development of integrated photonics and reconfigurable devices that have been combined with quantum dots or are suitable for hybrid integration.Finally, we provide an outlook of employing quantum-dot platforms for practical applications in large-scale quantum computation and the quantum Internet.
The recent developments of optoelectronics do promote the progress in many other fields. For quantum information processing, we made efforts in manufacturing quantum devices by using optoelectronic techniques. We designed quantum dot embedded nanocavities to serve as efficient quantum emitters; using spectral multiplexing technique, we fabricated a heralded single-photon source, emitting highly pure and speedy single photons; and defects in GaN were observed serving as room temperature quantum random number generators. An entangled photon emitter with visibility of 97% was developed using cascaded second-order nonlinear optical process in PPLN waveguides; and Si3N4 microrings were effectively applied to establish photon entanglers. Readout circuits were optimized to fabricate specific single-photon avalanche detectors, and telecomm-band single-photon avalanche detectors have been improved to 128 × 32 arrays for quantum imaging. A multiplexed quantum memory was explored to simultaneously store 1650 single photons. Opto-electro-mechanical devices were studied or fabricated in order to measure minor quantities in quantum level. These works may shed light on quantum information technology for the future.