公开(公告)号：US20250068959A1

公开(公告)日：2025-02-27

申请号：US18941942

申请日：2024-11-08

Applicant: Google LLC

Inventor： Kevin Chenghao Miao ,  Alexander Korotkov ,  Matthew James McEwen ,  Rami Barends

IPC: G06N10/70 ,  G06N10/40

Abstract: Methods, systems and apparatus for resetting a qubit. In one aspect, an apparatus includes a qubit, wherein the state of the qubit occupies a plurality of levels comprising two computational levels and one or more non-computational levels; a resonator that operates at a resonator frequency; control electronics that control a frequency of the qubit such that during a reset operation the qubit frequency is adjusted from a holding frequency that is lower than the resonator frequency to an idling frequency that is higher than the resonator frequency, and during the adjustment a first derivative of the qubit frequency at a first time is positive, at a second time that occurs after the first time is zero, and at a third time that occurs after the second time is positive, where the qubit frequency achieves the idling frequency at a fourth time that occurs after the third time.

公开(公告)号：US20220374750A1

公开(公告)日：2022-11-24

申请号：US17623385

申请日：2019-10-25

Applicant: Google LLC

Inventor： Vadim Smelyanskiy ,  Alexander Korotkov ,  Sergio Boixo Castrillo

IPC: G06N10/20 ,  G06N10/40

Abstract: Methods, systems and apparatus for estimating the fidelity of a quantum computing system. In one aspect, a method includes defining one or more random quantum circuits, wherein a noisy experimental implementation of each random quantum circuit is approximated by a depolarizing channel with respective polarization parameter; generating, for each defined random quantum circuit and by the quantum computing system, a set of experimental data, wherein data items in the set of experimental data comprise measured bit strings corresponding to experimental implementations of the random quantum circuit; determining, for each of the one or more random quantum circuits, an estimate of the respective polarization parameter, comprising maximizing a log-likelihood of the polarization parameter conditioned on the respective set of experimental data using series inversion; and determining an estimate of the fidelity of the quantum computing system based on the determined estimates of respective polarization parameters.

公开(公告)号：US20220230087A1

公开(公告)日：2022-07-21

申请号：US17623128

申请日：2019-10-30

Applicant: Google LLC

Inventor： Sergio Boixo Castrillo ,  Vadim Smelyanskiy ,  Hartmut Neven ,  Alexander Korotkov

IPC: G06N10/20 ,  G06N10/40

Abstract: Methods, systems and apparatus for estimating the fidelity of quantum logic gates. In one aspect, a method includes defining multiple sets of random quantum circuits; for each set of random quantum circuits: selecting an observable for each element in the set of random quantum circuits, wherein each selected observable corresponds to a respective element of the set of random quantum circuits and is dependent on the element to which it corresponds; estimating a value of a polarization parameter for the set of random quantum circuits, comprising performing a least mean squares minimization based on multiple expectation values, wherein each expectation value comprises an expectation value of a respective selected observable with respect to an output of an experimental implementation of a random quantum circuit corresponding to the respective selected observable; and processing the estimated polarization parameter values to obtain an estimate of the fidelity of the n-qubit quantum logic gate.

公开(公告)号：US12141661B2

公开(公告)日：2024-11-12

申请号：US18305152

申请日：2023-04-21

Applicant: Google LLC

Inventor： Kevin Chenghao Miao ,  Alexander Korotkov ,  Matthew James McEwen ,  Rami Barends

IPC: G06N10/70 ,  G06N10/40

Abstract: Methods, systems and apparatus for resetting a qubit. In one aspect, an apparatus includes a qubit, wherein the state of the qubit occupies a plurality of levels comprising two computational levels and one or more non-computational levels; a resonator that operates at a resonator frequency; control electronics that control a frequency of the qubit such that during a reset operation the qubit frequency is adjusted from a holding frequency that is lower than the resonator frequency to an idling frequency that is higher than the resonator frequency, and during the adjustment a first derivative of the qubit frequency at a first time is positive, at a second time that occurs after the first time is zero, and at a third time that occurs after the second time is positive, where the qubit frequency achieves the idling frequency at a fourth time that occurs after the third time.

公开(公告)号：US20230342651A1

公开(公告)日：2023-10-26

申请号：US18305174

申请日：2023-04-21

Applicant: Google LLC

Inventor： Kevin Chenghao Miao ,  Alexander Korotkov ,  Matthew James McEwen ,  Rami Barends ,  Juan Carlos Atalaya Chavez

IPC: G06N10/70 ,  G06N10/40

CPC classification number: G06N10/70 ,  G06N10/40

Abstract: Methods, systems and apparatus for transporting data qubit leakage. In one aspect, an apparatus includes, for a data qubit that has been operated on by a quantum computing system to place the data qubit in a first state, wherein the first state encodes logical information: preparing, by the quantum computing system, an ancilla qubit in a known initial state; and performing, by the quantum computing system, a leakage transport operation using one or more two-qubit gates on the data qubit and the ancilla qubit to transfer leakage from the data qubit to the ancilla qubit.