Experimental demonstration of an efficient, semi-device-independent photonic indistinguishability witness

Abstract

Efficient and reliable measurements of photonic indistinguishability are crucial to solidify claims of a quantum advantage in photonics. Existing indistinguishability witnesses may be vulnerable to implementation loopholes, showing the need for a measurement which depends on as few assumptions as possible. Here, we introduce a semi-device-independent witness of photonic indistinguishability and measure it on an integrated photonic processor, certifying three-photon indistinguishability in a way that is insensitive to implementation errors in our processor.

Quantifying n-photon indistinguishability with a cyclic integrated interferometer

“…In fact, totally destructive interference may also be observed in case of partially-distinguishable photon states that still obey certain symmetries [25]. At present, only witnesses of indistinguishability have been proposed [16,26], while a general technique to quantitatively measure the genuine indistinguishability of many photons is missing.…”