Purifying Photon Indistinguishability through Quantum Interference
Carlos F. D. Faurby, Lorenzo Carosini, Huan Cao, Patrik I. Sund, L. M. Hansen, Francesco Giorgino, Andrew B. Villadsen, S. N. van den Hoven, Peter Lodahl, Stefano Paesani, J. C. Loredo, Philip John Walther · Physical Review Letters · 2024
Indistinguishability between photons is a key requirement for scalable photonic quantum technologies. We experimentally demonstrate that partly distinguishable single photons can be purified to reach near-unity indistinguishability by the process of quantum interference with ancillary photons followed by heralded detection of a subset of them. We report on the indistinguishability of the purified photons by interfering two purified photons and show improvements in the photon indistinguishability of 2.774(3)% in the low-noise regime, and as high as 10.2(5)% in the high-noise regime.