The wave of a photon/Other experiments

Hong–Ou–Mandel Interferometer C. K. Hong Z. Y. Ou yes L. Mandel Measurement of subpicosecond time intervals between two photons by interference Phys. Rev. Lett. 59 18 2044–2046 1987 10.1103/PhysRevLett.59.2044 10035403 1987PhRvL..59.2044H 400px|thumb|Hong–Ou–Mandel diagram The Hong-Ou-Mandel interferometer is a variant of the Mach-Zehnder interferometer in which two simultaneous photons are compared. A 351 nm laser radiates a KDP crystal, which because of SPDC emits now and then two entangled photons of about 702 nm. The KDP is propably a type I, in which both photons have the same polarization and the same phase. Both waves are mixed in a 50% reflecting mirror, filtered by a bandpass interference filter IF and detected with a coincidence of 7.2 ns. It is supposed that this beam splitter is a glass plate with reflector on one side, causing (only) the reflection from the normal input having a phase shift of π. All other have no phase shift. At the detectors the waves are: Iu = 0.5sin(π+ωt+φ/2) + 0.5sinαsin(ωt-φ/2) and Il = 0.5sin(ωt+φ/2) + 0.5sinαsin(ωt-φ/2). With an ideal bandwidth filter d = Δω/ω, the probability is calculated: Pu = 0.5 - 0.5cos(4πΔx/λ) sin(πd(2k+2Δx/λ)) / πd(2k+2Δx/λ) and Pl = 0.5 + 0.5cos(4πΔx/λ) sin(πd(2k+2Δx/λ)) / πd(2k+2Δx/λ) These formula predicts the result of the measurement if the cosine term is ignored and k = 0. Then the formula will be: Pu = 0.5 - 0.5sin(πd2Δx/λ) / πd2Δx/λ Pl = 0.5 + 0.5sin(πd2Δx/λ) / πd2Δx/λ coincident: P = Pu * Pl 305px|thumb|Beam spliter displacement compared to norm In the experiment ω = 2πc/702nm = 2.7 1015. The bandwidth filter is 3 1013, d = 3 1013 / 2.7 1015 = 0.011. Then FWHM = 113 μm. References