US 12,467,732 B2
Precision quantum-interference-based non-local contactless measurement
Paul G Kwiat, Savoy, IL (US); Colin P Lualdi, Weston, MA (US); Spencer Johnson, El Paso, TX (US); and Kristina Meier, Urbana, IL (US)
Assigned to The Board of Trustees of the University of Illinois, Urbana, IL (US)
Filed by THE BOARD OF TRUSTEES OF THE UNIVERSITY OF ILLINOIS, Urbana, IL (US)
Filed on Sep. 20, 2022, as Appl. No. 17/948,308.
Claims priority of provisional application 63/249,256, filed on Sep. 28, 2021.
Prior Publication US 2025/0003730 A1, Jan. 2, 2025
Int. Cl. G01B 9/02001 (2022.01); G01H 9/00 (2006.01); G01S 17/08 (2006.01)
CPC G01B 9/02007 (2013.01) [G01H 9/00 (2013.01); G01S 17/08 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system comprising:
a photon source configured to generate pairs of photons that are frequency-entangled across first and second wavelengths, wherein the photon source comprises: (i) a constituent source configured to generate pairs of photons that are polarization-entangled, (ii) a polarizing beamsplitter, and (iii) a half wave plate, wherein the polarizing beamsplitter and half wave plate are arranged to receive pairs of photons that are polarization-entangled and that are generated by the constituent source, and to convert the pairs of photons from being polarization-entangled to being frequency-entangled across the first and second wavelengths;
an interferometer coupled to the photon source such that a first photon from a photon pair generated by the photon source is directed along a reference leg of the interferometer and a second photon from the photon pair generated by the photon source is directed along a sample leg of the interferometer such that the first photon and second photon are directed into an input of a beamsplitter of the interferometer;
a first photodetector, a second photodetector, a third photodetector, and a fourth photodetector, wherein the first and second photodetectors are configured to detect photons at the first wavelength, wherein the third and fourth photodetectors are configured to detect photons at the second wavelength, and wherein the first and second photodetectors are configured to receive photons emitted from respective first and second outputs of the beamsplitter; and
a leg actuator, wherein the leg actuator is operable to adjust an effective path length of one of the reference leg or the sample leg of the interferometer.