Symmetry Allows for Distinguishability in Totally Destructive Many-Particle Interference

A Franson Interferometer for Broadband Frequency-Entangled Photon Pairs

“…However, it must be stated that the setup itself was not designed to measure HOM interference and a certain lack of performance should be expected. Also, even recent experiments dedicated to HOM interference have reported visibilities around 90 % [14,39], but, visibilities larger than 95 % have been measured as well [40,41], most notably in [42] with up to 98.2 %, which used very similar equipment, for example the same BBO crystal with the same opening angle and narrow bandpass filters with comparable bandwidth.…”

“…There is, however, due to the frequency anticorrelation of the photon pair, with the spectral filters one component which acts different. Compared to the detection rate of a photon pair R C = η A η B • ν single , the single photon detection ratios R A/B are enhanced by a factor[57,58] C = dω A dω B |p(ω A/B )Φ(ω A , ω B )| 2 dω A dω B |p(ω A )p(ω B )Φ(ω A , ω B )| 2 ,(58)determined by integration of the joint spectral amplitude Φ(ω A , ω B ) and the spectral filter amplitudes p(ω A/B ). Therefore, the single count rates are given by R A/B = C • η A/B • ν single , where ν single is the single pair emission rate from the SPDC process into the detectable spatio-spectral modes.…”

Quantifying n-photon indistinguishability with a cyclic integrated interferometer

“…While the observation of these suppression effects can be used to discriminate truly indistinguishable single-photon ensembles from other alternative input states [23,24], this has not been exploited to effectively quantify the genuine multi-photon indistinguishability. 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.…”

Fast and efficient demultiplexing of single photons from a quantum dot with resonantly enhanced electro-optic modulators

“…The interference of multiple non-interacting, indistinguishable particles is the driving mechanism behind the rich dynamics of multi-photon quantum optics [1][2][3][4][5] and sets the stage for advanced quantum information protocols, such as boson sampling, [6][7][8][9][10] quantum simulation, 11,12 and quantum networks. 13 The required multi-photon states are typically generated by spontaneous parametric down conversion (SPDC) sources.…”