Dispersion measurement device and method based on franson second-order quantum interference technology

A dispersion measurement device based on a Franson second-order quantum interference technology, configured to measure a to-be-measured dispersive medium, and comprising:

• an energy-time entangled twin-photon source configured to generate a plurality of optical signals, wherein the optical signals each comprise a signal photon and an idle photon;
• a polarization splitter configured to split the signal photon and the idle photon, and enable the signal photon to pass through the to-be-measured dispersive medium;
• a first interference module configured to perform beam splitting on the idle photon, output idle photons obtained after the beam splitting to a first line and a second line respectively, delay the idle photon passing through the first line, and then perform beam combination on the delayed idle photon and the idle photon on the second line to enable the idle photons input from the first line and the second line to have a first preset arm length difference, such that after a first single-photon detector detects an idle photon obtained after the beam combination, a correlation time processing module records, under a width of a coincidence measurement integration window, first time of the idle photon arriving at the first single-photon detector;
• a second interference module configured to perform beam splitting on the signal photon, output signal photons obtained after the beam splitting to a third line and a fourth line respectively, delay the signal photon passing through the third line, and then perform beam combination on the delayed signal photon and the signal photon on the fourth line to enable the signal photons input from the third line and the fourth line to have a second arm length difference, such that after a second single-photon detector detects a signal photon obtained after the beam combination, the correlation time processing module records, under the width of the coincidence measurement integration window, second time of the signal photon arriving at the second single-photon detector, wherein a delay length of the signal photon passing through the third line is determined by a delay length of the idle photon passing through the first line;
• the correlation time processing module configured to obtain a coincidence count based on the first time and the second time;
• and
• a processing module configured to obtain a corresponding twin-photon time-domain coherence width based on the coincidence count, to calculate a dispersion value of the to-be-measured dispersive medium based on the twin-photon time-domain coherence width and the width of the coincidence measurement integration window.