# US 12,001,922 B2 · Quantum circuit and quantum processor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,001,922 B2 - Document ID: US12001922B2 - Status: Granted - Kind: B2 - Application number: 17/668,380 - Filed: 2022-02-09 - Published: 2022-08-25 - Granted: 2024-06-04 - Earliest claimed: 2021-01-27 - Assignees: Tencent Technology (Shenzhen) Company Limited - Applicants: Tencent Technology (Shenzhen) Company Limited - Inventors: Yu Zhou; Zhenxing Zhang; Shuoming An; Zelong Yin; Sainan Huai; Xiu Gu; Xiong Xu; Shengyu Zhang - Web page: https://patentgrep.com/patent/US12001922B2 ## CPC - G06N 10/40: Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control - G06N 10/20: Models of quantum computing, e.g. quantum circuits or universal quantum computers - G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS ## Abstract A quantum circuit includes: a qubit, a resonant cavity, and a feeder, the resonant cavity being coupled to the qubit, and the feeder being coupled to the qubit. The feeder is configured to feed an initialization signal to the qubit, the initialization signal being a modulation signal used for causing a frequency of the qubit to generate a vibration. The vibration causes an equivalent state exchange to occur between the qubit and the resonant cavity, and an excited state of the qubit is initialized to a ground state by using the resonant cavity. ## Claims ### Claim 1 A quantum circuit, comprising: a qubit, a resonant cavity, and a feeder, the resonant cavity being coupled to the qubit, and the feeder being coupled to the qubit, wherein: the feeder is configured to feed an initialization signal to the qubit, the initialization signal being a modulation signal used for causing a frequency of the qubit to generate a vibration, wherein a modulation frequency of the initialization signal is determined according to a modulation order; and the vibration causes an equivalent state exchange to occur between the qubit and the resonant cavity, so as to enable a transition from an excited state of the qubit to a ground state by using the resonant cavity. ### Claim 2 (depends on 1) The quantum circuit according to claim 1, wherein Φ=A cos(ωt+ϕ) Φ represents the initialization signal, A represents a modulation amplitude of the initialization signal, ω represents a modulation frequency of the initialization signal, ϕ represents a modulation phase of the initialization signal, and t represents time. ### Claim 3 (depends on 1) The quantum circuit according to claim 1, wherein the feeder is a magnetic flux bias line. ### Claim 4 (depends on 1) The quantum circuit according to claim 1, wherein when an energy level of a sideband generated by the vibration and an energy level of the resonant cavity meet an approach condition, an equivalent state exchange occurs between the qubit and the resonant cavity. ### Claim 5 (depends on 1) The quantum circuit according to claim 1, wherein when a frequency difference between an operating point of the qubit and a sweet spot is less than or equal to a threshold, a modulation order of the initialization signal is an even number greater than or equal to 2, wherein the operating point of the qubit refers to a frequency of the qubit in an initialization state. ### Claim 6 (depends on 1) The quantum circuit according to claim 1, wherein when a frequency difference between an operating point of the qubit and a sweet spot is greater than a threshold, a modulation order of the initialization signal is an integer greater than or equal to 1, wherein the operating point of the qubit refers to a frequency of the qubit in an initialization state. ### Claim 7 (depends on 1) The quantum circuit according to claim 1, wherein ω=δ/N+α wherein ω represents the modulation frequency of the initialization signal, δ is a frequency difference between the qubit and the resonant cavity, N represents a modulation order of the initialization signal, and α is an allowable deviation range. ### Claim 8 (depends on 1) The quantum circuit according to claim 1, wherein the qubit is a frequency-adjustable superconducting qubit. ### Claim 9 A quantum processor, comprising a quantum circuit, wherein: the quantum circuit comprises: a qubit, a resonant cavity, and a feeder, the resonant cavity being coupled to the qubit, and the feeder being coupled to the qubit; the feeder is configured to feed an initialization signal to the qubit, the initialization signal being a modulation signal used for causing a frequency of the qubit to generate a vibration, wherein a modulation frequency of the initialization signal is determined according to a modulation order; and the vibration causes an equivalent state exchange to occur between the qubit and the resonant cavity, so as to enable a transition from an excited state of the qubit to a ground state by using the resonant cavity. ### Claim 10 (depends on 9) The quantum processor according to claim 9, wherein Φ=A cos(ωt+ϕ) Φ represents the initialization signal, A represents a modulation amplitude of the initialization signal, ω represents a modulation frequency of the initialization signal, ϕ represents a modulation phase of the initialization signal, and t represents time. ### Claim 11 (depends on 9) The quantum processor according to claim 9, wherein the feeder is a magnetic flux bias line. ### Claim 12 (depends on 9) The quantum processor according to claim 9, wherein when an energy level of a sideband generated by the vibration and an energy level of the resonant cavity meet an approach condition, an equivalent state exchange occurs between the qubit and the resonant cavity. ### Claim 13 (depends on 9) The quantum processor according to claim 9, wherein when a frequency difference between an operating point of the qubit and a sweet spot is less than or equal to a threshold, a modulation order of the initialization signal is an even number greater than or equal to 2, wherein the operating point of the qubit refers to a frequency of the qubit in an initialization state. ### Claim 14 (depends on 9) The quantum processor according to claim 9, wherein when a frequency difference between an operating point of the qubit and a sweet spot is greater than a threshold, a modulation order of the initialization signal is an integer greater than or equal to 1, wherein the operating point of the qubit refers to a frequency of the qubit in an initialization state. ### Claim 15 (depends on 9) The quantum processor according to claim 9, wherein ω=δ/N+α wherein ω represents the modulation frequency of the initialization signal, δ is a frequency difference between the qubit and the resonant cavity, N represents a modulation order of the initialization signal, and α is an allowable deviation range. ### Claim 16 (depends on 9) The quantum processor according to claim 9, wherein the qubit is a frequency-adjustable superconducting qubit. ### Claim 17 A method implemented by a quantum circuit, the quantum circuit comprising: a qubit, a resonant cavity, and a feeder, the resonant cavity being coupled to the qubit, and the feeder being coupled to the qubit, the method comprising: feeding, by the feeder, an initialization signal to the qubit, the initialization signal being a modulation signal used for causing a frequency of the qubit to generate a vibration, wherein a modulation Frequency of the initialization signal is determined according to a modulation order; and causing, by the vibration, an equivalent state exchange to occur between the qubit and the resonant cavity, so as to enable a transition from an excited state of the qubit to a ground state by using the resonant cavity. ### Claim 18 (depends on 17) The method according to claim 17, wherein Φ=Acos(ωt+ϕ) Φ represents the initialization signal, A represents a modulation amplitude of the initialization signal, ω represents a modulation frequency of the initialization signal, ϕ represents a modulation phase of the initialization signal, and t represents time . ### Claim 19 (depends on 17) The method according to claim 17, wherein the feeder is a magnetic flux bias line. ### Claim 20 (depends on 17) The method according to claim 17, wherein the modulation frequency of the initialization signal is determined according to a frequency difference between the qubit and the resonant cavity, a modulation order of the initialization signal, and an allowable deviation range.