Hong-Ou-Mandel Interferometer

Abstract

The effect of a decoherence channel, such as a turbulent atmosphere, on the second order quantum interference in the Hong-Ou-Mandel (HOM) effect is investigated. The investigation includes both theoretical analyses and an experimental implementation of the process. In our experiment, entangled input states are prepared with spontaneous parametric down-conversion. The atmospheric turbulence is modelled as a single-phase screen and simulated with a spatial light modulator according to the theory of Kolmogorov. We find both theoretically and experimentally that the HOM dip is unaffected when only one of the photons passes through turbulence, but both photons pass through turbulence, the HOM interference is only slightly affected by the scintillation. The reasons behind these findings and their consequences for HOM-based teleportation are discussed.

Translation from a Distinguishable to Indistinguishable Two-Photon State

“…Assuming that the spectra and bandwidths of the signal photons and the translated idler photons are Gaussian and identical to the bandpass filters BF2 and BF3 (130 GHz), respectively, we find the coherence times of the photons to be 0.44/130 GHz = 3.4 ps. As the temporal width of the HOM dips is √2 times longer than the coherence time of the input photons, the anticipated HOM-dip width is 4.8 ps. A discrepancy is noted compared to the simulated and measured width (5.8 and 6.0 ± 0.3 ps), which can be attributed to the flat-top shape of the filters employed in our experiment.…”

Squeezing a Surface Plasmon through Quadratic Nonlinear Interactions

“…It is still necessary to acquire a description of nonclassical SPP states from the level of the interaction of a single SPP quanta. For photons, nonlinear optical interactions devote a convenient platform for generating nonclassical states such as squeezed states − or entangled photon states. − Inspired by these interactions, we consider squeezing an SPP through parametric down conversion. Recent developments of nonlinear plasmonics also provide relevant bases. − …”

Jinmao Tower and Shanghai World Financial Center, Shanghai, China

“…A HOM interference can be arranged by combining two independent heralded sources on a beam-splitter. The four-fold coincidence probability can be written as follows [57] : P (t) = dω s1 dω s2 dω i1 dω i2 |f ′ (ω s1 , ω i1 )f ′ (ω s2 , ω i2 ) −f ′ (ω s2 , ω i1 )f ′ (ω s1 , ω i2 ) • e −i(ωs 2 −ωs 1 )t | 2 ,(B1) where t denotes the path delay between two independent sources.…”