# US 11,994,428 B1 · Self-triaging photon detector

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- Number: US 11,994,428 B1
- Document ID: US11994428B1
- Status: Granted
- Kind: B1
- Application number: 18/110,851
- Filed: 2023-02-16
- Granted: 2024-05-28
- Earliest claimed: 2019-10-21
- Assignees: Psiquantum, Corp.
- Applicants: PsiQuantum Corp.
- Inventors: Faraz Najafi
- Web page: https://patentgrep.com/patent/US11994428B1

## CPC

- G01J 1/44: Electric circuits {(for command of an exposure part G03B7/02)}
- H03K 17/92: by the use, as active elements, of superconductive devices
- G01J 1/0407: {Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings}
- H03K 17/941: {using an optical detector (H03K17/968 takes precedence)}
- G01J 2001/442: {Single-photon detection or photon counting}
- G01J 2001/4446: {Type of detector}
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A photon detecting component is provided. The photon detecting component includes a first waveguide and a detecting section. The detecting section includes a second waveguide; a detector, optically coupled with the second waveguide, configured to detect one or more photons in the second waveguide; an optical switch configured to provide an optical coupling between the first waveguide and the second waveguide when the detector is operational; and an electrical switch electrically coupled to the detector, wherein the electrical switch is configured to change state in response to the detector detecting one or more photons. The photon detecting component further includes readout circuitry configured to determine a state of the electrical switch of the detecting section.

## Claims

### Claim 1

A photon detecting method, comprising:
in accordance with a first photon detector being operational, coupling a first waveguide to a second waveguide with a first optical switch for transferring photons in the first waveguide to the second waveguide, wherein the first photon detector is optically coupled to the second waveguide;
while the first photon detector is operational, detecting, at the first photon detector, one or more photons from the second waveguide; and
changing a state of a first electrical switch that is electrically coupled to the first photon detector in response to the first photon detector detecting one or more photons.

### Claim 2 (depends on 1)

The photon detecting method of claim 1, wherein the first optical switch is a micromechanical optical switch.

### Claim 3 (depends on 1)

The photon detecting method of claim 1, further including, for each respective photon detector of a plurality of additional photon detectors:
in accordance with a determination that the respective photon detector is operational, coupling the first waveguide to a respective additional waveguide with a respective optical switch for transferring photons in the first waveguide to the respective additional waveguide, wherein the respective photon detector is optically coupled to the respective additional waveguide;
while the respective photon detector is operational, detecting, at the respective photon detector, one or more photons in the respective additional waveguide; and
changing a state of a respective electrical switch that is electrically coupled to the respective photon detector in response to the respective photon detector detecting one or more photons.

### Claim 4 (depends on 1)

The photon detecting method of claim 1, wherein the first photon detector comprises a first superconducting component, and the method includes transitioning the first superconducting component from a superconducting state to a non-superconducting state in response to detecting one or more photons.

### Claim 5 (depends on 4)

The photon detecting method of claim 4, wherein:
the first optical switch and the first electrical switch are connected in parallel with the first superconducting component; and
the method includes:
changing states of the first optical switch, with a first time constant, in response to the first superconducting component transitioning from the superconducting state to the non-superconducting state; and
changing states of the first electrical switch, with a second time constant shorter than the first time constant, in response to the first superconducting component transitioning from the superconducting state to the non-superconducting state.

### Claim 6 (depends on 5)

The photon detecting method of claim 5, wherein the first optical switch has a first inductance and the first electrical switch has a second inductance that is lower than the first inductance.

### Claim 7 (depends on 1)

The photon detecting method of claim 1, further including providing a current, and routing a first portion of the current to the first electrical switch in response to the first photon detector detecting one or more photons.

### Claim 8 (depends on 7)

The photon detecting method of claim 7, including, in accordance with the first photon detector not being operational:
routing a second portion of the current to the first optical switch; and
routing a third portion of the current to the first electrical switch, wherein the third portion of the current is below a threshold for changing the state of the first electrical switch.

### Claim 9 (depends on 1)

The photon detecting method of claim 1, wherein the first electrical switch is coupled with a variable resistor of a readout line, and the method further includes:
in response to the first photon detector detecting one or more photons, changing, via the first electrical switch, a resistance of the variable resistor; and
measuring, via readout circuitry, a change in the resistance of the variable resistor.

### Claim 10 (depends on 9)

The photon detecting method of claim 9, wherein the variable resistor is thermally coupled with the first electrical switch.

### Claim 11 (depends on 1)

The photon detecting method of claim 1, further comprising transitioning the first electrical switch from a superconducting state to a non-superconducting state in response to the first photon detector detecting one or more photons.

### Claim 12 (depends on 11)

The photon detecting method of claim 11, wherein the first electrical switch is configured to generate sufficient heat in the non-superconducting state to increase a temperature of a variable resistor above a superconducting threshold temperature for the variable resistor.

### Claim 13 (depends on 1)

The photon detecting method of claim 1, wherein the first electrical switch comprises a resistive heater.

### Claim 14 (depends on 13)

The photon detecting method of claim 13, further comprising generating, at the resistive heater, sufficient heat to increase a temperature of a second superconducting component above a superconducting threshold temperature for the second superconducting component, wherein the second superconducting component operates as a variable resistor.

### Claim 15 (depends on 1)

The photon detecting method of claim 1, wherein the first electrical switch comprise a piezoelectric component, and the method further includes:
applying, via the piezoelectric component, a first strain to a second superconducting component in response to the first photon detector detecting one or more photons, wherein the second superconducting component operates as a variable resistor.

### Claim 16 (depends on 15)

The photon detecting method of claim 15, further including, transitioning the second superconducting component from a superconducting state to a non-superconducting state in response to the first strain.

### Claim 17 (depends on 1)

The photon detecting method of claim 1, further including determining, via readout circuitry, a state of a respective electrical switch of each photon detector of a plurality of photon detectors, the plurality of photon detectors including the first photon detector.