US 12,283,998 B2
Method and apparatus for mapping out sources of decoherence in quantum channels
Michael Brodsky, Millburn, NJ (US); Cristian Antonelli, Sulmona (IT); Daniel E. Jones, Nottingham, MD (US); and Gabriele Riccardi, Rome (IT)
Assigned to The United States America as represented by the Secretary of the Army, Washington, DC (US)
Filed by U.S. Army DEVCOM, Army Research Laboratory, Adelphi, MD (US)
Filed on Jan. 24, 2023, as Appl. No. 18/100,857.
Claims priority of provisional application 63/302,373, filed on Jan. 24, 2022.
Prior Publication US 2023/0261762 A1, Aug. 17, 2023
Int. Cl. H04B 10/70 (2013.01); H04B 10/079 (2013.01)
CPC H04B 10/70 (2013.01) [H04B 10/079 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method of characterizing an optical channel, comprising:
generating, using an entangled photon source (EPS), pairs of entangled photons, wherein first entangled photons A of the generated pairs of entangled photons are coupled to a first optical channel and second entangled photons B of the generated pairs of entangled photons are coupled to a second optical channel, wherein the first channel comprises an optical channel to be characterized and the second channel comprises a local storage optical channel;
detecting, at each of the first and second channels, respective entangled photons, wherein each entangled photon A is expressed in the basis (hA, hA′) and each corresponding entangled photon B is expressed in the basis (hB, hB′);
determining quantum coincidence data (QCD) of detected entangled photons A and B;
measuring quantum-correlation along (hA, hB′) and (hA′, hB) of the detected entangled photons using the determined QCD; and
responsive to (hA, hB′) being greater than (hA′, hB), characterizing the first channel as a modal loss first channel;
responsive to (hA, hB′) being less than (hA′, hB), characterizing the first channel as a decoherence first channel.