Granted Patent B2

US 12,289,135 · App. 18/863,938 · Granted Apr 29, 2025

Inventors: Liam Bussey (London, GB); Amelia Lees (London, GB); Fraser Burton (London, GB); Marco Menchetti (London, GB); Timothy Whitley (London, GB)

Assignee: BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY

H04B10/70G01R29/0885H04B10/60H04B2210/006

Abstract

Claims (31)

1. A method of detecting a photon in a first frequency range, the method comprising the steps of:

exciting a first transmission medium by a first probe signal at a first probe frequency, wherein the first probe signal excites electrons of the first transmission medium from a ground state of the first transmission medium to a first excited state of the first transmission medium;

exciting the first transmission medium by a first coupling signal at a first coupling frequency, wherein the first coupling signal overlaps with the first probe signal in the first transmission medium and excites the electrons of the first transmission medium to a predetermined excited state of the first transmission medium such that a first photon in the first frequency range and having a first polarisation incident upon the first transmission medium excites an electron in the predetermined excited state of the first transmission medium to a further excited state of the first transmission medium, wherein a first photon in a second frequency range is emitted as part of a subsequent deexcitation of the electron from the further excited state of the first transmission medium;

detecting the first photon in the first frequency range and having the first polarisation by detecting the first photon in the second frequency range;

exciting a second transmission medium by a second probe signal at a second probe frequency, wherein the second probe signal excites electrons of the second transmission medium from a ground state of the second transmission medium to a first excited state of the second transmission medium;

exciting the second transmission medium by a second coupling signal at a second coupling frequency, wherein the second coupling signal overlaps with the second probe signal in the second transmission medium and excites the electrons of the second transmission medium to a predetermined excited state of the second transmission medium such that a second photon in the first frequency range incident upon the second transmission medium and having a second polarisation excites an electron in the predetermined excited state of the second transmission medium to a further excited state of the second transmission medium, wherein a second photon in the second frequency range is emitted as part of a subsequent deexcitation of the electron in the further excited state of the second transmission medium; and

detecting the second photon in the first frequency range having the second polarisation by detecting the second photon in the second frequency range.

2. The method as claimed in claim 1 , wherein the method further comprises the steps of:

demodulating data based on detection of the first photon in the first frequency range having the first polarisation corresponding to a first bit value, and detection of the second photon in the first frequency range having the second polarisation corresponding to a second bit value.

3. The method as claimed in claim 2 , further comprising the step of:

determining a cryptographic key based on the demodulated data.

4. The method as claimed in claim 1 , wherein the first frequency range is lower than the second frequency range.

5. The method as claimed in claim 1 , wherein the first frequency range is in the Radio Frequency (RF), microwave or infrared ranges of the electromagnetic spectrum.

6. A non-transitory computer readable carrier medium storing a computer program, which upon execution by a computer, causes the steps of the method of claim 1 to be performed.

7. A device for detecting a photon in a first frequency range, the detector comprising:

a first transmission medium excitable by a first probe signal at a first probe frequency and an overlapping first coupling signal at a first coupling frequency, wherein the first probe frequency excites electrons of the first transmission medium from a ground state of the first transmission medium to a first excited state of the first transmission medium and the first coupling frequency excites the electrons of the first transmission medium to a predetermined excited state of the first transmission medium such that a first photon in a first frequency range and having a first polarisation incident upon the first transmission medium excites an electron in the predetermined excited state of the first transmission medium to a further excited state of the first transmission medium, wherein a first photon in a second frequency range is emitted as part of a subsequent deexcitation of the electron in the further excited state of the first transmission medium;

a first detector configured to detect the first photon in the first frequency range having the first polarisation by detecting the first photon in the second frequency range;

a second transmission medium excitable by a second probe signal at a second probe frequency and an overlapping second coupling signal at a second coupling frequency, wherein the second probe frequency excites electrons of the second transmission medium from a ground state of the second transmission medium to a first excited state of the second transmission medium, wherein the second coupling frequency excites the electrons of the second transmission medium to a predetermined excited state of the second transmission medium such that a second photon in the first frequency range having a second polarisation incident upon the second transmission medium excites an electron in the predetermined excited state of the second transmission medium to a further excited state of the second transmission medium, wherein a second photon in the second frequency range is emitted as part of a subsequent deexcitation of the electron in the further excited state of the second transmission medium; and

a second detector configured to detect the second photon in the first frequency range having the second polarisation by detecting the second photon in the second frequency range.

8. The device as claimed in claim 7 , further comprising:

a housing configured to permit passage of the first photon in the first frequency range to the first transmission medium when arriving in a predetermined direction.

9. The device as claimed in claim 7 , further comprising:

a processor configured to demodulate data based on detection of the first photon in the first frequency range having the first polarisation corresponding to a first bit value and detection of the second photon in the first frequency range having the second polarisation corresponding to a second bit value.

10. The device as claimed in claim 9 , wherein the processor is further configured to determine a cryptographic key based on the demodulated data.

11. The device as claimed in claim 7 , wherein the first frequency range is lower than the second frequency range.

12. The device as claimed in claim 7 , wherein the first frequency range is in the Radio Frequency (RF), microwave or infrared ranges of the electromagnetic spectrum.

13. A system comprising:

a first transmission medium excitable by a first probe signal at a first probe frequency and an overlapping first coupling signal at a first coupling frequency, wherein the first probe frequency excites electrons of the first transmission medium from a ground state of the first transmission medium to a first excited state of the first transmission medium and the first coupling frequency excites the electrons of the first transmission medium to a predetermined excited state of the first transmission medium such that a first photon in a first frequency range and having a first polarisation incident upon the first transmission medium excites an electron in the predetermined excited state of the first transmission medium to a further excited state of the first transmission medium, wherein a first photon in a second frequency range is emitted as part of a subsequent deexcitation of the electron in the further excited state of the first transmission medium;

a first detector configured to detect the first photon in the first frequency range and having the first polarisation by detecting the first photon in the second frequency range;

a second transmission medium excitable by a second probe signal at a second probe frequency and an overlapping second coupling signal at a second coupling frequency, wherein the second probe frequency excites electrons of the second transmission medium from a ground state of the second transmission medium to a first excited state of the second transmission medium, wherein the second coupling frequency excites the electrons of the second transmission medium to a predetermined excited state of the second transmission medium such that a second photon in the first frequency range and having a second polarisation incident upon the second transmission medium excites an electron in the predetermined excited state of the second transmission medium to a further excited state of the second transmission medium, wherein a second photon in the second frequency range is emitted as part of a subsequent deexcitation of the electron in the further excited state of the second transmission medium; and

a second detector configured to detect the second photon in the first frequency range and having the second polarisation by detecting the second photon in the second frequency range.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (32)