Improving the indistinguishability of single photons from an ion-cavity system

We investigate two schemes for generating indistinguishable single photons, a key feature of quantum networks, from a trapped ion coupled to an optical cavity. Through selection of the initial state in a cavity-assisted Raman transition, we suppress the detrimental effects of spontaneous emission on the photon's coherence length, measuring a visibility of 81(2)% without subtraction of background counts in a Hong-Ou-Mandel interference measurement, the highest reported for an ion-cavity system. In comparison, a visbility of 50(2)% was measured using a more conventional single photon scheme. We demonstrate through numerical analysis of the single photon generation process that the new scheme produces photons of a given indistinguishability with a greater efficiency than the conventional one. Single photon schemes such as the one demonstrated here have applications in distributed quantum computing and communications, which rely on high fidelity entanglement swapping and state transfer through indistinguishable single photons