In a single-photon double-slit experiment the two slits
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Interference and diffraction · Photodetection, photonic sources and quantum optics
Optics and Photonics, Ch The photon
Problem
In a single-photon double-slit experiment the two slits, each of width b=0.050 mm, are separated by d=0.25 mm. Light of wavelength λ=633 nm falls on the slits and detections are recorded on a screen L=2.0 m beyond them, one dot at a time. With both slits open, thousands of dots build up the usual two-slit fringe pattern of spacing λL/d. A student, holding the picture that "each photon splits in half and goes through both slits", predicts that closing one slit should still leave a fringe pattern on the screen, just at half the overall brightness, since half of each photon can no longer get through.
((a)) State what pattern of dots is actually observed once one slit is covered, and name the rule (from Chapter 12) that governs it.
((b)) Compute the distance from the central maximum to the first minimum of that pattern.
((c)) Explain, using the fact that every detection is a single whole click at one point, why the half-photon picture is wrong.