Dynamic adaptive thresholding for qubit reset

Patent metadata

Field	Value
Publication number	US-2024020569-A1
Application number	US-202217813082-A
Country	US
Kind code	A1
Filing date	Jul 18, 2022
Priority date	Jul 18, 2022
Publication date	Jan 18, 2024
Grant date	—

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 the computer executable components stored in the memory, wherein the computer executable components comprise:
a decision component 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.

2 . The system of claim 1 , wherein the decision component is configured to selectively determine the threshold based on one or more electrical, mechanical or structural parameters of a qubit physical circuit comprising the qubit or on one or more electrical, mechanical or structural parameters of a quantum device comprising the qubit.

3 . The system of claim 1 , further comprising:
a readout component configured to determine a plurality of measurements defining plural states of the qubit at different instances; a calibration component configured to integrate the plurality of measurements to map the plural states to one-dimensional signal values representing a selected probability distribution for excited and ground states of the qubit; and a classification component that is configured to, based on the signal values, calculate the probability distribution of state classification error of the qubit, wherein the decision component is configured to apply a threshold of the different thresholds that minimizes the probability of state classification error of the qubit.

4 . The system of claim 3 , wherein the decision component is configured to selectively determine the threshold based on one or more electrical, mechanical or structural parameters of a qubit physical circuit comprising the qubit or on one or more electrical, mechanical or structural parameters of a quantum device comprising the qubit.

5 . The system of claim 1 , wherein the decision component is configured to employ a supervised learning model that determines the threshold to apply for a particular quantum circuit based on one or more kernels that apply to the particular quantum circuit or to the environment of the qubit, and wherein the kernels are written based on a plurality of calibration measurements defining plural states of the qubit at different instances.

6 . The system of claim 1 , further comprising:
a classification component that is configured to, based on a plurality of calibration measurements defining plural states of the qubit at different instances, calculate the probability distribution of state classification error of the qubit, wherein the decision component is configured to determine a threshold of the different thresholds to apply to the qubit based on the probability distribution of state classification error of the qubit.

7 . The system of claim 6 , wherein the decision component is configured to further determine the threshold of the different thresholds to apply to the qubit based on one or more kernels that define a use of the qubit, and wherein the kernels correspond to the plurality of calibration measurements.

8 . The system of claim 1 , further comprising:
a readout component that is configured to measure a state of the qubit; and a pulse generation component that is configured to generate a pulse that resets the qubit to the ground state of the qubit based on a determination that the qubit is in the excited state, wherein a threshold of the different thresholds is applied to provide the determination.

9 . A computer-implemented method, comprising:
determining, by a system operatively coupled to a processor, 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.

10 . The computer-implemented method of claim 9 , further comprising:
selectively determining the threshold based on one or more electrical, mechanical or structural parameters of a qubit physical circuit comprising the qubit or on one or more electrical, mechanical or structural parameters of a quantum device comprising the qubit.

11 . The computer-implemented method of claim 9 , further comprising:
determining, by the system, a plurality of measurements defining plural states of the qubit at different instances; integrating, by the system, the plurality of measurements to map the plural states to one-dimensional signal values representing a selected probability distribution for excited and ground states of the qubit; calculating, by the system, and based on the signal values, the probability distribution of state classification error of the qubit; and applying, by the system, a threshold of the different thresholds that minimizes the probability of state classification error of the qubit.

12 . The computer-implemented method of claim 11 , further comprising:
determining, by the system, the threshold based on one or more electrical, mechanical or structural parameters of a qubit physical circuit comprising the qubit or on one or more electrical, mechanical or structural parameters of a quantum device comprising the qubit.

13 . The computer-implemented method of claim 9 , further comprising:
employing, by the system, a supervised learning model that determines the threshold to apply for a particular quantum circuit based on one or more kernels that apply to the particular quantum circuit or to the environment of the qubit; and writing, by the system, the kernels based on a plurality of calibration measurements defining plural states of the qubit at different instances.

14 . The computer-implemented method of claim 9 , further comprising:
calculating, by the system, based on a plurality of calibration measurements defining plural states of the qubit at different instances, the probability distribution of state classification error of the qubit; and determining, by the system, a threshold of the different thresholds to apply to the qubit based on the probability distribution of state classification error of the qubit.

15 . The computer-implemented method of claim 14 , further comprising:
determining, by the system, the threshold of the different thresholds to apply to the qubit based on one or more kernels that define a use of the qubit, wherein the kernels correspond to the plurality of calibration measurements.

16 . The computer-implemented method of claim 9 , further comprising:
measuring, by the system, a state of the qubit; and generating, by the system, a pulse that resets the qubit to the ground state of the qubit based on a determination that the qubit is in the excited state, wherein a threshold of the different thresholds is applied to provide the determination.

17 . 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 computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
determine, by the processor, a threshold of a plurality of thresholds to apply to measurement of a state of the qubit base

Assignees

• IBM

Inventors

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

Classifications

• G06N10/70 Primary

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

• G06N10/20

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

• G06N3/09

  Supervised learning · CPC title