A Predictable Bright Single-Photon Source

Anonymous

Nathan Moses, Marcus J. Clark, Alex S. Clark +2 more

Efficient and bright single photon sources on photonic chips are key to scaling quantum technologies. Spontaneous four wave mixing in micro-ring resonators creates excellent narrowband and tunable photon sources. We experimentally demonstrate the optimization of heralding efficiency and brightness by tuning the coupling of the pump, signal and idler modes into the resonator whilst operating in a pulsed pump regime. We observe a maximum detected pair rate of over 93,000~coincidences per second in a moderately over-coupled regime, alongside a high intrinsic idler heralding efficiency of 97.87$\pm$8.97\% when operating close to maximal over-coupling. The measured dependence on coupling strength is in strong agreement with theoretical predictions, experimentally validating the predicted trade-off between brightness and heralding efficiency.

Olivier Gazzano, Marcelo Pereira de Almeida, A. K. Nowak +5 more

We demonstrate the unambiguous entangling operation of a photonic quantum-logic gate driven by an ultrabright solid-state single-photon source. Indistinguishable single photons emitted by a single semiconductor quantum dot in a micropillar optical cavity are used as target and control qubits. For a source brightness of 0.56 photons per pulse, the measured truth table has an overlap with the ideal case of 68.4±0.5%, increasing to 73.0±1.6% for a source brightness of 0.17 photons per pulse. The gate is entangling: At a source brightness of 0.48, the Bell-state fidelity is above the entangling threshold of 50% and reaches 71.0±3.6% for a source brightness of 0.15.

Michael E. Reimer, Catherine Cher

Igor A. Khramtsov, Dmitry Yu. Fedyanin

Practical applications exploiting the quantum nature of light require efficient and bright room-temperature single-photon sources. At present, color centers in diamond are considered to be the most promising candidates. However, their efficient electrical excitation is challenging due to the inability to create a high density of free electrons in diamond. In this work, we predict the superinjection effect in diamond homojunction p-i-n diodes, which enables to inject up to four orders of magnitude more electrons into the i-region than the doping of the n-type region allows. Despite that the superinjection effect is known to be a unique feature of semiconductor heterostructures, we demonstrate for the first time that this effect can also be observed in homojunction diamond diodes, giving the possibility to overcome the doping problem and design bright electrically driven single-photon sources.