Analyzing quantum information processing circuits

Patent metadata

Field	Value
Publication number	US-10140404-B2
Application number	US-201515301051-A
Country	US
Kind code	B2
Filing date	Nov 6, 2015
Priority date	Nov 6, 2015
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

In a general aspect, a quantum information processing circuit is analyzed. In some implementations, a linear response function of a quantum information processing circuit is generated. A linear circuit model is generated based on the linear response function. A composite circuit model is generated by combining the linear circuit model and a nonlinear circuit model. An operating parameter of the quantum information processing circuit is computed by solving the composite circuit model. In some implementations, an electromagnetic structure solver determines the linear response function based on a circuit specification, a quantum circuit analysis tool calculates the operating parameters, and the circuit specification is modified based on the operating parameters.

First claim

What is claimed is:

1. A method of determining physical operating parameters of a quantum information processing circuit, the method comprising:
by operation of a design tool executed by one or more processors in a computer system, generating a circuit specification for a quantum information processing circuit comprising a qubit device;
storing the circuit specification in a memory of the computer system;
loading the circuit specification from the memory into a workspace of an electromagnetic structure solver executed by one or more processors in the computer system;
by operation of the electromagnetic structure solver, analyzing the quantum information processing circuit to obtain a linear response function of the quantum information processing circuit, wherein the linear response function represents a linear component of the quantum information processing circuit, and wherein obtaining the linear response function comprises imposing a passivity condition and a positive real condition on a fitted linear response function;
storing the linear response function in the memory of the computer system; and
by operation of a quantum circuit analysis tool executed by one or more processors in the computer system:
accessing the linear response function from the memory;
determining circuit parameters of a multi-mode resonator circuit based on the linear response function and a circuit topology of the multi-mode resonator circuit, wherein the circuit parameters of the multi-mode resonator circuit are determined using a Brune circuit synthesis algorithm;
generating a linear circuit model based on the circuit parameters and the circuit topology, wherein the linear circuit model comprises a first Hamiltonian representing the multi-mode resonator circuit;
generating a composite circuit model based on combining the linear circuit model and a nonlinear circuit model, the nonlinear circuit model comprising a second Hamiltonian representing a nonlinear component in the quantum information processing circuit, wherein generating the composite circuit model comprises generating a composite Hamiltonian by combining the first Hamiltonian with the second Hamiltonian;
computing a numerical solution to the Schrödinger equation for the composite Hamiltonian, wherein the numerical solution comprises at least three quantum energy levels of the qubit device in the quantum information processing circuit;
extracting physical operating parameters of the quantum information processing circuit from the numerical solution to the Schrödinger equation, wherein the physical operating parameters include a coherence time of the qubit device and a resonance frequency of the qubit device; and
storing the physical operating parameters in the memory of the computer system;
by operation of the design tool, modifying the circuit specification based on the physical operating parameters; and
manufacturing a quantum processor chip based on the modified circuit specification.

2. The method of claim 1 , comprising obtaining multiple operating parameters of the quantum information processing circuit based on a second order or higher order solution to the Schrödinger equation.

3. The method of claim 1 , wherein the quantum information processing circuit comprises a single-port quantum information processing circuit that includes the qubit device.

4. The method of claim 1 , wherein the quantum information processing circuit comprises a multi-port quantum information processing circuit that includes multiple nonlinear components, and the method comprises generating the composite circuit model based on the linear circuit model and nonlinear circuit models that represent the respective nonlinear components in the quantum information processing circuit.

5. The method of claim 1 , wherein the physical operating parameter further comprise a resonance frequency of a resonator device in the quantum information processing circuit.

6. The method of claim 1 , wherein the physical operating parameter further comprise a coupling strength between devices in the quantum information processing circuit.

7. The method of claim 1 , wherein the physical operating parameters further comprise a dispersive shift of a resonator device frequency in the quantum information processing circuit.

8. A system comprising:
one or more processors; and
a computer-readable medium storing instructions that, when executed by the one or more processors, perform operations comprising:
by operation of a design tool, generating a circuit specification for a quantum information processing circuit comprising a qubit device;
storing the circuit specification in a memory of the computing system;
loading the circuit specification from the memory into a workspace of the electromagnetic structure solver;
by operation of the electromagnetic structure solver, analyzing the quantum information processing circuit to obtain a linear response function of the quantum information processing circuit, wherein the linear response function represents a linear component of the quantum information processing circuit, and wherein obtaining the linear response function comprises imposing a passivity condition and a positive real condition on a fitted linear response function;
storing the linear response function in the memory of the computing system; and
by operation of a quantum circuit analysis tool:
accessing the linear response function from the memory;
determining circuit parameters of a multi-mode resonator circuit based on the linear response function and a circuit topology of the multi-mode resonator circuit, wherein the circuit parameters of the multi-mode resonator circuit are determined using a Brune circuit synthesis algorithm;
generating a linear circuit model based on the circuit parameters and the circuit topology, wherein the linear circuit model comprises a first Hamiltonian representing the multi-mode resonator circuit;
generating a composite circuit model based on combining the linear circuit model and a nonlinear circuit model, the nonlinear circuit model comprising a second Hamiltonian representing a nonlinear component in the quantum information processing circuit, wherein generating the composite circuit model comprises generating a composite Hamiltonian by combining the first Hamiltonian with the second Hamiltonian;
computing a numerical solution to the Schrödinger equation for the composite Hamiltonian, wherein the numerical solution comprises at least three quantum energy levels of the qubit device in the quantum information processing circuit;
extracting physical operating parameters of the quantum information processing circuit from the numerical solution to the Schrödinger equation, wherein the physical operating parameters include a coherence time of the qubit device and a resonance frequency of the qubit device; and
storing the physical operating parameters in the memory of the computing system; and
by operation of the design tool, modifying the circuit specification based on the physical operating parameters; and
a manufacturing system configured to manufacture a quantum processor chip based on the modified circuit specification.

9. The system of claim 8 , the operations comprising obtaining multiple operating parameters of the quantum information processing circuit based on a second order or higher order solution to the Schrödinger equation.

10. The system of claim 8 , wherein the operating parameters further include a resonance frequency of a resonator device in the quantum information processing circuit and a coupling strength between the qubit device and the resonator device.

11. The system of claim 8 , further comprising a display device that d

Assignees

• Rigetti & Co Inc
• Rigetti & Co Inc

Inventors

• Rigetti Chad T
• Sete Eyob A

Classifications

• G06F2119/18

  Manufacturability analysis or optimisation for manufacturability · CPC title

• G06F30/327

  Logic synthesis; Behaviour synthesis, e.g. mapping logic, HDL to netlist, high-level language to RTL or netlist · CPC title

• G06F30/23

  using finite element methods [FEM] or finite difference methods [FDM] · CPC title

• G06N7/00

  Computing arrangements based on specific mathematical models · CPC title

• G06N7/04

  Physical realisation · CPC title