# US 12,008,435 B2 · Frequency configuration in quantum gates for leakage removal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,008,435 B2 - Document ID: US12008435B2 - Status: Granted - Kind: B2 - Application number: 17/694,820 - Filed: 2022-03-15 - Published: 2022-12-29 - Granted: 2024-06-11 - Earliest claimed: 2021-03-15 - Assignees: Google Inc. - Applicants: Google LLC - Inventors: 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 - Web page: https://patentgrep.com/patent/US12008435B2 ## CPC - G06N 10/40: Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control - G06N 10/70: Quantum error correction, detection or prevention, e.g. surface codes or magic state distillation - G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS ## 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. ## Claims ### Claim 1 A quantum computing system configured for removal of leakage states, the quantum computing system comprising: quantum hardware comprising a first measurement qubit and a data qubit, wherein the first measurement qubit is configured to have a first transition frequency and wherein the data qubit is configured to have a second transition frequency, the first transition frequency being greater than the second transition frequency; and one or more quantum control devices configured to control operation of at least the first measurement qubit and the data qubit, wherein the one or more quantum control devices are configured to implement a quantum gate operation on the first measurement qubit and the data 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 measurement qubit. ### Claim 2 (depends on 1) The quantum computing system of claim 1, further comprising: a second measurement qubit configured to have a third transition frequency, the third transition frequency being less than the second transition frequency; and one or more quantum control devices configured to control operation of at least the data qubit and the second measurement qubit, wherein the one or more quantum control devices are configured to implement a quantum gate operation on the data qubit and the second measurement qubit based at least in part on the second transition frequency and the third transition frequency. ### Claim 3 (depends on 1) The quantum computing system of claim 1, wherein a |12> two-qubit state of the data qubit and the first measurement qubit is resonant with a |30> two-qubit state of the data qubit and the first measurement qubit, wherein the |12> two-qubit state comprises a |2> state of the data qubit, and the |30> state comprises a |3> state of the first measurement qubit. ### Claim 4 (depends on 1) The quantum computing system of claim 1, wherein the quantum gate operation comprises a diabatic quantum gate operation. ### Claim 5 (depends on 1) The quantum computing system of claim 1, wherein the quantum gate comprises a controlled gate operation. ### Claim 6 (depends on 5) The quantum computing system of claim 5, wherein the controlled gate operation comprises a controlled-Z gate operation. ### Claim 7 (depends on 1) The quantum computing system of claim 1, wherein the one or more quantum control devices are configured to periodically reset the quantum state of the first measurement qubit to a |0> state. ### Claim 8 A quantum computing system configured for removal of leakage states, the quantum computing system comprising: quantum hardware comprising a plurality of qubits arranged in a qubit grid, the plurality of qubits comprising one or more data qubits configured to implement quantum gate operations with a plurality of measurement qubits; wherein the quantum gate operations each comprise a higher-frequency side and a lower-frequency side, wherein each respective data qubit of the one or more data qubits is configured to implement at least one quantum gate operation having a lower-frequency side configured to be implemented at the respective data qubit of the one or more data qubits. ### Claim 9 (depends on 8) The quantum computing system of claim 8, wherein the plurality of qubits are arranged in a quantum surface code. ### Claim 10 (depends on 8) The quantum computing system of claim 8, wherein the quantum gate operations comprise diabatic quantum gate operations. ### Claim 11 (depends on 8) The quantum computing system of claim 8, wherein the quantum gate operations comprise controlled-Z gate operations. ### Claim 12 (depends on 8) The quantum computing system of claim 8, wherein, for each quantum gate operation implemented at at least one data qubit of the one or more data qubits, a lower-frequency side of the quantum gate operation is implemented at the at least one data qubit. ### Claim 13 (depends on 8) The quantum computing system of claim 8, wherein a lower-frequency side of two of the quantum gate operations is implemented at at least one data qubit of the one or more data qubits, and wherein a higher-frequency side of two of the quantum gate operations is implemented at the at least one data qubit. ### Claim 14 (depends on 13) The quantum computing system of claim 13, wherein each data qubit of the one or more data qubits implements four quantum gate operations. ### Claim 15 A method for implementing quantum gate operations, the method comprising: configuring, by one or more quantum control devices, a first measurement qubit of quantum hardware at a first transition frequency; configuring, by the one or more quantum control devices, a data qubit of the quantum hardware at a second transition frequency, the first transition frequency being greater than the second transition frequency; and implementing, by the one or more quantum control devices, a quantum gate operation at the first measurement qubit and the data qubit based at least in part on the first transition frequency and the second transition frequency; wherein the one or more quantum control devices are configured to periodically reset a quantum state of the first measurement qubit. ### Claim 16 (depends on 15) The method of claim 15, configuring, by one or more quantum control devices, a second measurement qubit of quantum hardware at a third transition frequency, the third transition frequency being less than the second transition frequency; implementing, by the one or more quantum control devices, a quantum gate operation at the second measurement qubit and the data qubit based at least in part on the first transition frequency and the third transition frequency. ### Claim 17 (depends on 15) The method of claim 15, wherein a |12> two-qubit state of the data qubit and the first measurement qubit is resonant with a |30> two-qubit state of the data qubit and the first measurement qubit, wherein the |12> two-qubit state comprises a |2> state of the data qubit, and the |30> state comprises a |3> state of the first measurement qubit. ### Claim 18 (depends on 15) The method of claim 15, wherein the quantum gate operation comprises a diabatic controlled-Z quantum gate. ### Claim 19 (depends on 15) The method of claim 15, wherein a frequency difference is present between the first transition frequency and the second transition frequency, wherein the quantum gate operation is implemented based at least in part on the frequency difference. ### Claim 20 (depends on 15) The method of claim 15, wherein the quantum hardware is arranged in a quantum surface code.