Number-resolving photon detector with graphene-insulating-superconducting junction

Patent metadata

Field	Value
Publication number	US-10454016-B2
Application number	US-201815983928-A
Country	US
Kind code	B2
Filing date	May 18, 2018
Priority date	May 19, 2017
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

A photon detector including a graphene-insulating-superconducting junction configured as a temperature sensor. Photons are absorbed by the graphene sheet of the graphene-insulating-superconducting junction, each absorbed photon causing a temporary increase in the temperature of the graphene sheet, and a corresponding change in the differential impedance of the graphene-insulating-superconducting junction. The graphene-insulating-superconducting junction is part of a resonant circuit connected as a shunt load between a radio frequency input transmission line and a radio frequency output transmission line. The transmission S-parameter from input to output is affected by the impedance of the resonant circuit which in turn is affected by the differential impedance of the graphene-insulating-superconducting junction, and therefore by the temperature of the graphene sheet. The absorption of photons is detected by detecting changes in the transmission S-parameter indicating temperature changes caused by the absorption of a photon.

First claim

What is claimed is:

1. A photon detector, having a sensing input for receiving photons, and comprising:
a graphene-insulating-superconducting junction comprising a graphene sheet; and
a sensing circuit, connected to the graphene-insulating-superconducting junction, for measuring a differential resistance of the graphene-insulating-superconducting junction,
the graphene sheet being configured to undergo, when a photon is absorbed by the graphene sheet, an increase in temperature and a subsequent decrease in temperature, resulting in corresponding changes in the differential resistance of the graphene-insulating-superconducting junction.

2. The photon detector of claim 1 , wherein the sensing circuit comprises:
an interrogation circuit connected to the graphene-insulating-superconducting junction; and
a receiver circuit connected to the graphene-insulating-superconducting junction,
the interrogation circuit being configured:
to generate an inbound radio frequency signal, and
to feed the inbound radio frequency signal to the graphene-insulating-superconducting junction,

the receiver circuit being configured to receive an outbound radio frequency signal from the graphene-insulating-superconducting junction.

3. The photon detector of claim 2 , wherein the sensing circuit further comprises a resonant circuit comprising the graphene-insulating-superconducting junction.

4. The photon detector of claim 3 , wherein:
the resonant circuit comprises a tank circuit, and
the tank circuit is connected in parallel with the graphene-insulating-superconducting junction.

5. The photon detector of claim 3 , wherein:
the resonant circuit has a resonant frequency and a bandwidth, and
the interrogation circuit is configured to generate a sequence of pulses,
each pulse having a frequency differing from the resonant frequency by less than the bandwidth.

6. The photon detector of claim 5 , wherein the sequence of pulses has a pulse repetition rate greater than or equal to the reciprocal of a thermal time constant of the graphene sheet.

7. The photon detector of claim 6 , wherein the sequence of pulses has a pulse repetition rate at least ten times greater than or equal to the reciprocal of the thermal time constant of the graphene sheet.

8. The photon detector of claim 5 , wherein the photon detector is configured to detect photons absorbed by the graphene sheet from changes in a transmission S-parameter, from the interrogation circuit to the receiver circuit, resulting from temperature changes in the graphene sheet caused by the absorption of the photons.

9. The photon detector of claim 5 , further comprising an impedance-matching element connected between the sensing input and the graphene-insulating-superconducting junction.

10. The photon detector of claim 9 , wherein the impedance-matching element is a quarter-wave section of transmission line.

11. The photon detector of claim 2 , further comprising:
a first bias tee; and
a second bias tee,
the first bias tee being connected between the interrogation circuit and the graphene-insulating-superconducting junction; and
the second bias tee being connected between the receiver circuit and the graphene-insulating-superconducting junction.

12. The photon detector of claim 11 , wherein:
the first bias tee comprises a first coupling capacitor having a first capacitance,
the second bias tee comprises a second coupling capacitor having a second capacitance, and
the second capacitance is greater than the first capacitance.

13. The photon detector of claim 11 , wherein:
the graphene-insulating-superconducting junction comprises a superconducting metal layer; and
the graphene-insulating-superconducting junction has:
a first contact connected to:
the graphene sheet,
the first bias tee, and
the second bias tee; and

a second contact connected to the superconducting metal layer of the graphene-insulating-superconducting junction,

the second contact being connected to ground.

14. The photon detector of claim 13 , wherein the graphene-insulating-superconducting junction has a sensing contact connected to the sensing input.

15. The photon detector of claim 14 , wherein the sensing contact is the first contact.

16. The photon detector of claim 14 , wherein the sensing contact is a contact, separate from the first contact, formed at an edge of the graphene sheet.

17. The photon detector of claim 1 , comprising:
a first layer of hexagonal boron nitride immediately adjacent a first surface of the graphene sheet, and
a second layer of hexagonal boron nitride immediately adjacent a second surface of the graphene sheet.

18. The photon detector of claim 17 , wherein each of the first layer of hexagonal boron nitride and the second layer of hexagonal boron nitride has a thickness greater than 1 nm and less than 1 micron.

19. The photon detector of claim 1 , wherein the graphene sheet consists of a single atomic layer of graphene.

20. The photon detector of claim 1 , wherein the graphene sheet comprises two atomic layers of graphene.

Assignees

• Raytheon Bbn Technologies Corp

Inventors

• Fong Kin Chung
• Ohki Thomas A

Classifications

• G01J5/24

  Use of specially adapted circuits, e.g. bridge circuits · CPC title

• G01J5/20 Primary

  using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices · CPC title

• G01J5/046

  Materials; Selection of thermal materials · CPC title

• H01L39/223

  Electricity · mapped topic

• H01L39/228

  Electricity · mapped topic