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US 10,650,321 B2Granted
Quantum phase estimation of multiple eigenvalues
AssigneeGoogle Inc.
InventorsRyan Babbush, Nan Ding
Life of this patent
Estimating the term…
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.
Claims20
A method comprising:
- accessing a first quantum register comprising at least one ancilla qubit and a second quantum register comprising one or more qubits, wherein the second quantum register is prepared in an arbitrary quantum state;
- performing a plurality of phase estimation experiments on the first quantum register, wherein each experiment comprises:
- preparing the ancilla qubit in a known quantum state;
- operating one or more times on the first quantum register and the second quantum register with a unitary operator;
- and
- subsequent to the operation of the unitary operator, measuring a state of the ancilla qubit;
- determining, by a phase learning subsystem, an expectation value of the state of the ancilla qubit based on results of the phase estimation experiments;
- and
- based on the determined expectation value of the state of the ancilla qubit and the measured states of the ancilla qubit, learning, by the phase learning subsystem, phases of the eigenvalues of the unitary operator by optimizing a model representing probabilities of the state of the ancilla qubit,
- wherein the model comprises a mixture model that is estimated using non-parametric Bayesian inference.
7 more elements
An apparatus comprising:
- 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 an arbitrary quantum state;
- a phase learning system, configured to learn phases of the eigenvalues of a unitary operator,
- wherein the apparatus is configured to:
- perform a plurality of phase estimation experiments on the first quantum register, wherein each experiment comprises:
- preparing the ancilla qubit in a known quantum state;
- operating one or more times on the first quantum register and the second
- quantum register with the unitary operator;
- and
- subsequent to the operation of the unitary operator, measuring a state of the ancilla qubit;
- determining, by the phase learning subsystem, an expectation value of the state of the ancilla qubit based on results of the phase estimation experiments;
- and
- based on the determined expectation value of the state of the ancilla qubit and the measured states of the ancilla qubit, learning, by the phase learning subsystem, phases of the eigenvalues of the unitary operator by optimizing a model representing probabilities of the state of the ancilla qubit, wherein the model comprises a mixture model that is estimated using non-parametric Bayesian inference.
11 more elements
Dependencies are inferred from the claim text.