Patent ID: 11962690
Assignee: UNIVERSITY OF CENTRAL FLORIDA RESEARCH FOUNDATION, INC.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 23:
24. A system comprising:
a transceiver comprising:
a light source configured to generate a faint pulse;
a state converter including an interferometer, wherein the state converter is configured to convert the faint pulse from a polarization-path state to a time-polarization state with a leading time bin and a lagging time bin, wherein the state converter includes a polarization converter in an arm of the interferometer to rotate light within the arm to an orthogonal polarization; and
a polarization randomizer to receive the faint pulse from the state converter, wherein the polarization randomizer applies a random polarization transformation to the faint pulse prior to transmission of the faint pulse through a communication channel; and

a quantum bit encoder to receive the faint pulse from the transceiver over the communication channel, wherein the quantum bit encoder comprises:
a phase modulator configured to apply a differential phase shift between the leading time bin and the lagging time bin of the faint pulse received through the communication channel as an encoded bit; and
a Faraday mirror to reflect the faint pulse back to the transceiver and rotate a polarization of the faint pulse to an orthogonal state;

wherein the transceiver is further configured to receive a return pulse through the communication channel, wherein the polarization randomizer is configured to apply an inverse of the random polarization transformation to the return pulse;
wherein the transceiver further comprises three or more detectors configured to measure the return pulse at time-gated timeslots associated with possible paths of the return pulse through at least the polarization randomizer and the state converter;
wherein reception of the faint pulse from the quantum bit encoder as the return pulse triggers a detector in a first detector subset of the three or more detectors; and
wherein reception of a faked-state pulse from a third party as the return pulse results in a non-zero probability of triggering of a detector in a second detector subset of the three or more detectors.