Figure 1
APS/Alan Stonebraker

Figure 1: (a) Superresolution and supersensitivity. Examples of interference fringes of (i) a single-photon interference fringe (dot-dash line, sin ϕ), (ii) interference fringe at twice the resolution from a two-photon NOON state (solid line, sin 2ϕ), and (iii) interference fringe obtained from classical light at twice the resolution, with reduced visibility (dashed line, 1/2sin 2ϕ). Example schematics of two-photon and classical-light interferometers. (b) Illustration of an n-photon Fock state in a diffraction limited beam falling on an array of detectors smaller than the beam. The optical centroid measurement uses postprocessing to harness all of the photon detection events to scalably detect the Fock state. Without this—even with photon-number-resolving single-photon detectors that are smaller than a diffraction limited spot—one cannot efficiently detect the Fock state |n〉.