Dynamic adaptive thresholding for qubit reset

Patent metadata

Field	Value
Publication number	US-12099903-B2
Application number	US-202217813082-A
Country	US
Kind code	B2
Filing date	Jul 18, 2022
Priority date	Jul 18, 2022
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

One or more systems, devices, computer program products and/or computer-implemented methods of use provided herein relate to a process to dynamically determine a threshold for determining a state of a qubit and apply the threshold for operating a pulse to de-excite the qubit. A system can comprise a memory that stores computer executable components, and a processor that executes the computer executable components stored in the memory, wherein the computer executable components can comprise a decision component that is configured to determine a threshold of a plurality of thresholds to apply to measurement of a state of a qubit based on a probability distribution of state of the qubit, wherein a measurement at one side of the threshold is representative of the qubit being in the ground state, and wherein a measurement at another side of the threshold is representative of the qubit being in an excited state.

First claim

What is claimed is:

1. A system, comprising:
a memory that stores computer executable components; and
a processor that executes at least one of the computer executable components that:
determines a threshold of a plurality of thresholds to employ in performing a real-time measurement of a state of a qubit of a quantum processing device, wherein a measurement at one side of the threshold is representative of the qubit being in a ground state, and wherein a measurement at another side of the threshold is representative of the qubit being in an excited state, wherein the determining comprises:
determining, based on a plurality of measurements defining plural states of the qubit at different instances, a first probability distribution of a state readout of the qubit being erroneously classified as the ground state,
determining, based on the plurality of measurements defining the plural states of the qubit at the different instances, a second probability distribution of the state readout of the qubit being erroneously classified as the excited state, and
selecting the threshold from the plurality of thresholds based on respective errors determined for the plurality of thresholds using the first probability distribution and the second probability distribution.

2. The system of claim 1 , wherein the selecting is further based on one or more electrical, mechanical or structural parameters of at least one of a qubit physical circuit comprising the qubit or the quantum processing device.

3. The system of claim 1 , wherein the at least one of the computer executable components further:
integrates the plurality of measurements to map the plural states to one-dimensional signal values.

4. The system of claim 1 , wherein the the determining the threshold employs a supervised learning model that determines the threshold to apply for a quantum circuit comprising the qubit based on one or more kernels that apply to the quantum circuit, and wherein the one or more kernels are written based on the plurality of measurements.

5. The system of claim 1 , wherein at least one of the first probability distribution or the second probability distribution is determined using a normal cumulative distribution function.

6. The system of claim 1 , wherein the determining the threshold is further based on one or more kernels that define a use of the qubit, and wherein the one or more kernels correspond to the plurality of measurements.

7. The system of claim 1 , wherein the at least one of the computer executable components further:
measures the state of the qubit; and
generates a pulse that resets the qubit to the ground state based on a determination, using the threshold, that the qubit is in the excited state.

8. A computer-implemented method, comprising:
determining, by a system operatively coupled to a processor, a threshold of a plurality of thresholds to employ in performing a real-time measurement of a state of a qubit of a quantum processing device, wherein a measurement at one side of the threshold is representative of the qubit being in a ground state, and wherein a measurement at another side of the threshold is representative of the qubit being in an excited state, wherein the determining comprises:
determining, based on a plurality of measurements defining plural states of the qubit at different instances, a first probability distribution of a state readout of the qubit being erroneously classified as the ground state,
determining, based on the plurality of measurements defining the plural states of the qubit at the different instances, a second probability distribution of the state readout of the qubit being erroneously classified as the excited state, and
selecting the threshold from the plurality of thresholds based on respective errors determined for the plurality of thresholds using the first probability distribution and the second probability distribution.

9. The computer-implemented method of claim 8 , wherein the selecting is further based on one or more electrical, mechanical or structural parameters of at least one of a qubit physical circuit comprising the qubit or the quantum processing device.

10. The computer-implemented method of claim 8 , wherein the determining the threshold further comprises:
integrating the plurality of measurements to map the plural states to one-dimensional signal values.

11. The computer-implemented method of claim 8 , further comprising:
writing, by the system, one or more kernels based on the plurality of measurements; and
employing, by the system, a supervised learning model that determines the threshold to apply for a quantum circuit comprising the qubit based on the one or more kernels.

12. The computer-implemented method of claim 8 , wherein at least one of the first probability distribution or the second probability distribution is determined using a normal cumulative distribution function.

13. The computer-implemented method of claim 8 , further comprising:
determining, by the system, the threshold to apply to the qubit based on one or more kernels that define a use of the qubit, wherein the one or more kernels correspond to the plurality of measurements.

14. The computer-implemented method of claim 8 , further comprising:
measuring, by the system, the state of the qubit; and
generating, by the system, a pulse that resets the qubit to the ground state based on a determination, using the threshold, that the qubit is in the excited state.

15. A computer program product enabling a process to dynamically determine a threshold for determining a state of a qubit, the computer program product comprising a non-transitory computer readable medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
determine, by the processor, the threshold of a plurality of thresholds to employ in performing a real-time measurement of the state of the qubit of a quantum processing device, wherein a measurement at one side of the threshold is representative of the qubit being in a ground state, and wherein a measurement at another side of the threshold is representative of the qubit being in an excited state, wherein the determining comprises:
determining, based on a plurality of measurements defining plural states of the qubit at different instances, a first probability distribution of a state readout of the qubit being erroneously classified as the ground state,
determining, based on the plurality of measurements defining the plural states of the qubit at the different instances, a second probability distribution of the state readout of the qubit being erroneously classified as the excited state, and
selecting the threshold from the plurality of thresholds based on respective errors determined for the plurality of thresholds using the first probability distribution and the second probability distribution.

16. The computer program product of claim 15 , wherein the program instructions are further executable by the processor to cause the processor to:
write, by the processor, one or more kernels based on the plurality of measurements; and
employ, by the processor, a supervised learning model that determines the threshold to apply for a quantum circuit comprising the qubit based on the one or more kernels.

17. The computer program product of claim 15 , wherein the program instructions are further executable by the processor to cause the processor to:
determine, by the processor, the threshold to apply to the qubit based on one or more kernels that define a use of the qub

Assignees

• IBM

Inventors

• Inoue Ken
• Takita Maika
• Corcoles-Gonzalez Antonio
• Lekuch Scott Douglas

Classifications

• G06N10/20

  Models of quantum computing, e.g. quantum circuits or universal quantum computers · CPC title

• G06N3/09

  Supervised learning · CPC title

• G06N10/70 Primary

  Quantum error correction, detection or prevention, e.g. surface codes or magic state distillation · CPC title

• G06N10/40 Primary

  Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control · CPC title