公开(公告)号：US11270222B2

公开(公告)日：2022-03-08

申请号：US16841320

申请日：2020-04-06

Applicant: Google LLC

Inventor： Ryan Babbush ,  Nan Ding

IPC: G06N10/00 ,  G06F17/10

Abstract: Methods, systems, and apparatus for quantum phase estimation. In one aspect, an apparatus includes a quantum circuit comprising a first quantum register comprising at least one ancilla qubit, quantum gates, comprising at least (i) two Hadamard gates, (ii) a phase gate, (iii) a unitary operator, and (iv) a measurement operator, a second quantum register comprising one or more qubits, wherein the second quantum register is prepared in an arbitrary quantum state that is not an eigenstate of the unitary operator; and a phase learning system, configured to perform phase estimation experiments on the quantum circuit, comprising repeatedly measuring the state of an ancilla qubit for each phase estimation experiment to determine an expectation value of the state of the ancilla qubit and learn phases of the eigenvalues of the unitary operator.

公开(公告)号：US20210295198A1

公开(公告)日：2021-09-23

申请号：US17339125

申请日：2021-06-04

Applicant: Google LLC

Inventor： Ryan Babbush ,  Hartmut Neven

IPC: G06N10/00 ,  G06F15/16 ,  G06N20/00 ,  B82Y10/00

Abstract: Methods, systems, and apparatus for training quantum evolutions using sub-logical controls. In one aspect, a method includes the actions of accessing quantum hardware, wherein the quantum hardware includes a quantum system comprising one or more multi-level quantum subsystems; one or more control devices that operate on the one or more multi-level quantum subsystems according to one or more respective control parameters that relate to a parameter of a physical environment in which the multi-level quantum subsystems are located; initializing the quantum system in an initial quantum state, wherein an initial set of control parameters form a parameterization that defines the initial quantum state; obtaining one or more quantum system observables and one or more target quantum states; and iteratively training until an occurrence of a completion event.

公开(公告)号：US20210174236A1

公开(公告)日：2021-06-10

申请号：US16967339

申请日：2019-08-07

Applicant: Google LLC

Inventor： Ryan Babbush ,  Ian David Kivlichan

IPC: G06N10/00 ,  G06F15/16

Abstract: Methods, systems and apparatus for performing quantum state preparation. In one aspect, a method includes the actions of defining a target quantum state of a quantum system, wherein time evolution of the quantum system is governed by a target Hamiltonian, and defining a total Hamiltonian that interpolates between an initial Hamiltonian and the target Hamiltonian, wherein the total Hamiltonian is equal to the initial Hamiltonian at an initial time and is equal to the target Hamiltonian at a final time; approximating the time evolution of the total Hamiltonian using a truncated linear combination of unitary simulations to generate a truncated time evolution operator; evolving a ground state of the initial Hamiltonian according to the truncated time evolution operator for a truncated number of time steps to generate an intermediate state; and variationally adjusting the intermediate state to determine a wavefunction that approximates the target quantum state of the quantum system.

公开(公告)号：US10650321B2

公开(公告)日：2020-05-12

申请号：US16067428

申请日：2015-12-30

Applicant: GOOGLE LLC

Inventor： Ryan Babbush ,  Nan Ding

IPC: G06N10/00 ,  G06F17/10

Abstract: Methods, systems, and apparatus for quantum phase estimation. In one aspect, an apparatus includes a quantum circuit comprising: a first quantum register comprising at least one ancilla qubit, a second quantum register comprising one or more qubits, wherein the second quantum register is prepared in a quantum state that is not an eigenstate of a unitary operator operating on the first and second quantum register; and a phase learning system, configured to learn phases of the eigenvalues of the unitary operator.