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公开(公告)号：US12299533B2
公开(公告)日：2025-05-13
申请号：US18080614
申请日：2022-12-13
Applicant: Google LLC
Inventor： Sergio Boixo Castrillo , Vadim Smelyanskiy
IPC: G06N10/20 , G06F7/544 , G06F30/3308 , G06N10/80
Abstract: Methods, systems and apparatus for simulating quantum circuits including multiple quantum logic gates. In one aspect, a method includes the actions of representing the multiple quantum logic gates as functions of one or more classical Boolean variables that define a undirected graphical model with each classical Boolean variable representing a vertex in the model and each function of respective classical Boolean variables representing a clique between vertices corresponding to the respective classical Boolean variables; representing the probability of obtaining a particular output bit string from the quantum circuit as a first sum of products of the functions; and calculating the probability of obtaining the particular output bit string from the quantum circuit by directly evaluating the sum of products of the functions. The calculated partition function is used to (i) calibrate, (ii) validate, or (iii) benchmark quantum computing hardware implementing a quantum circuit.
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公开(公告)号：US12067457B2
公开(公告)日：2024-08-20
申请号：US16981075
申请日：2019-01-31
Applicant: Google LLC
Inventor： Vadim Smelyanskiy , Andre Petukhov , Rami Barends , Sergio Boixo Castrillo
IPC: H03K19/195 , G06N10/00 , G06N10/20 , G06N10/60
Abstract: Methods, systems and apparatus for implementing iSWAP quantum logic gates between a first qubit and a second qubit. In one aspect, a method includes implementing a cascade schedule that defines a trajectory of a detuning between a frequency of the first qubit and a frequency of the second qubit. Implementing the cascade schedule includes: during a first stage, adiabatically driving detuning between the frequency of the first qubit and the frequency of the second qubit through a first avoided crossing in a leakage channel; during a second stage, driving detuning between the frequency of the first qubit and the frequency of the second qubit through a second avoided crossing in a swap channel; during a third stage, evolving the first qubit and second qubit; during a fourth stage, implementing the second stage in reverse order; and during a fifth stage, implementing the first stage in reverse order.
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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
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.
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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
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.
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公开(公告)号：US20220012622A1
公开(公告)日：2022-01-13
申请号：US17339276
申请日：2021-06-04
Applicant: Google LLC
Inventor： Yuezhen Niu , Hartmut Neven , Vadim Smelyanskiy , Sergio Boixo Castrillo
Abstract: Methods, systems, and apparatus for implementing a unitary quantum gate on one or more qubits. In one aspect, a method includes the actions designing a control pulse for the unitary quantum gate, comprising: defining a universal quantum control cost function, wherein the control cost function comprises a qubit leakage penalty term representing i) coherent qubit leakage, and ii) incoherent qubit leakage across all frequency components during a time dependent Hamiltonian evolution that realizes the unitary quantum gate; adjusting parameters of the time dependent Hamiltonian evolution to vary a control cost according to the control cost function such that leakage errors are reduced; generating the control pulse using the adjusted parameters; and applying the control pulse to the one or more qubits to implement the unitary quantum gate.
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Patent Agency Ranking
公开(公告)号：US12182665B2
公开(公告)日：2024-12-31
申请号：US17928349
申请日：2021-05-27
Applicant: Google LLC
Inventor： Yuezhen Niu , Trevor Johnathan McCourt , Masoud Mohseni , Vadim Smelyanskiy
Abstract: Errors that affect a quantum computer can be efficiently measured and characterized by placing the quantum computer in a highly-entangled state such as a Greenberger-Horne-Zeilinger (GHZ) state, accumulating quantum errors in the highly entangled state, and then measuring the accumulated errors. In some approaches, the error characterization includes measuring parity oscillations of the GHZ state and fitting a quantum error model to a power spectrum of the parity oscillations. The fitted quantum error model can be used to select a suitable fault-tolerant error correction scheme for the quantum computer given its environmental noise.
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公开(公告)号：US12050964B1
公开(公告)日：2024-07-30
申请号：US17010944
申请日：2020-09-03
Applicant: Google LLC
Inventor： Yuezhen Niu , Vadim Smelyanskiy , Sergio Boixo Castrillo
Abstract: The present disclosure provides systems and methods to measure quantum gate fidelity through swap spectroscopy. In particular, aspects of the present disclosure are directed to the derivation and use of a physical model that models non-Markovian quantum dynamics of interactions between one or more qubits of a quantum gate and one or more two-level-system (TLS) defects during operation of the quantum gate.
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公开(公告)号：US12008435B2
公开(公告)日：2024-06-11
申请号：US17694820
申请日：2022-03-15
Applicant: Google LLC
Inventor： Alexander Nikolaevich Korotkov , Kevin Joseph Satzinger , Matthew James McEwen , Vadim Smelyanskiy , Paul Victor Klimov , Rami Barends , Julian Shaw Kelly , Juan Carlos Atalaya-Chavez , Zijun Chen
CPC classification number: G06N10/40
Abstract: A quantum computing system configured for removal of leakage states can include quantum hardware including a first qubit and a second qubit, wherein the first qubit is configured to have a first transition frequency and wherein the second qubit is configured to have a second transition frequency, the first transition frequency being greater than the second transition frequency. The quantum computing system can include one or more quantum control devices configured to control operation of at least the first qubit and the second qubit, wherein the one or more quantum control devices are configured to implement a quantum gate operation on the first qubit and the second qubit based at least in part on the first transition frequency and the second transition frequency, and wherein the one or more quantum control devices are configured to periodically reset a quantum state of the first qubit.
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公开(公告)号：US11809957B2
公开(公告)日：2023-11-07
申请号：US16981606
申请日：2019-01-31
Applicant: Google LLC
Inventor： Yuezhen Niu , Vadim Smelyanskiy , Sergio Boixo Castrillo
Abstract: Methods, systems and apparatus for implementing a quantum gate on a quantum system comprising a second qubit coupled to a first qubit and a third qubit. In one aspect, a method includes evolving a state of the quantum system for a predetermined time, wherein during evolving: the ground and first excited state of the second qubit are separated by a first energy gap ω; the first and second excited state of the second qubit are separated by a second energy gap equal to a first multiple of ω minus qubit anharmoniticity−; the ground and first excited state of the first qubit and third qubit are separated by a third energy gap equal to ω−; and the first and second excited state of the first qubit and third qubit are separated by a fourth energy gap equal to the first multiple of the ω minus a second multiple of .
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公开(公告)号：US20220027773A1
公开(公告)日：2022-01-27
申请号：US17433445
申请日：2019-03-05
Applicant: Google LLC
Inventor： Vadim Smelyanskiy , Andre Petukhov , Rami Barends , Sergio Boixo Castrillo , Yu Chen
IPC: G06N10/00
Abstract: Methods, systems and apparatus for generating plunge schedules for implementing iSWAP quantum logic gates between a first qubit and a second qubit. In one aspect, a plunge schedule that defines a trajectory of a detuning between a frequency of the first qubit and a frequency of the second qubit includes, during a first stage, non-adiabatically driving detuning between the frequency of the first qubit and the frequency of the second qubit through a first avoided crossing in a leakage channel, during a second stage, driving detuning between the frequency of the first qubit and the frequency of the second qubit through a second avoided crossing in a swap channel. during a third stage, allowing the first qubit and the second qubit to freely evolve and interact, during a fourth stage, implementing the second stage in reverse order, and during a fifth stage, implementing the first stage in reverse order.
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