Abstract: Systems and methods for calibrating and initializing a system comprising a first qubit, a second qubit, and a coupler are provided. A method of initializing the system can include calibrating the system; providing a first idle resonance frequency of the first qubit and a second idle resonance frequency of the second qubit; providing the first bias for the first idle resonance frequency and the second bias for the second idle resonance frequency; determining a value of the third resonance frequency at which a difference between the first degree of coupling and the second degree of coupling is minimized, when the first resonance frequency is the first idle resonance frequency and the second resonance frequency is the second idle resonance frequency; and providing the third bias according to the determined value of the third resonance frequency.

Abstract: Systems and methods for composite quantum gate calibration for a quantum computing system are provided. In some implementations, a method includes accessing a unitary gate model describing a composite quantum gate. The unitary gate model includes a plurality of gate parameters. The method includes implementing the composite quantum gate for a plurality of gate cycles on the quantum system to amplify the plurality of gate parameters. The method includes obtaining a measurement of a state of the quantum system after implementing the composite quantum gate for the plurality of gate cycles. The method includes determining at least one of the plurality of gate parameters based at least in part on the measurement of the state of the quantum system. The method includes calibrating the composite quantum gate for the quantum computing system based at least in part on the plurality of gate parameters.

Abstract: The disclosure is directed to a quantum processor system. The system includes a transmission line, a resonator, a qubit coupled to the resonator, and a switching device that couples and decouples the resonator to the transmission line. The resonator stores a range of energies based on a frequency that characterizes the resonator. When a quantum state of the qubit is equivalent to an excited state and the qubit is tuned in accordance with the frequency, energy is transferred from the qubit to the resonator, which stores the energy. The quantum state of the qubit is transitioned to a ground state. When the switching device is closed, the resonator is coupled to the transmission line such that the energy is transferred to the transmission line. When the switching device is opened, the resonator is decoupled from the transmission line.

Abstract: Systems and methods for calibrating and initializing a system comprising a first qubit, a second qubit, and a coupler are provided. A method of initializing the system can include calibrating the system; providing a first idle resonance frequency of the first qubit and a second idle resonance frequency of the second qubit; providing the first bias for the first idle resonance frequency and the second bias for the second idle resonance frequency; determining a value of the third resonance frequency at which a difference between the first degree of coupling and the second degree of coupling is minimized, when the first resonance frequency is the first idle resonance frequency and the second resonance frequency is the second idle resonance frequency; and providing the third bias according to the determined value of the third resonance frequency.

Abstract: Systems and methods for composite quantum gate calibration for a quantum computing system are provided. In some implementations, a method includes accessing a unitary gate model describing a composite quantum gate. The unitary gate model includes a plurality of gate parameters. The method includes implementing the composite quantum gate for a plurality of gate cycles on the quantum system to amplify the plurality of gate parameters. The method includes obtaining a measurement of a state of the quantum system after implementing the composite quantum gate for the plurality of gate cycles. The method includes determining at least one of the plurality of gate parameters based at least in part on the measurement of the state of the quantum system. The method includes calibrating the composite quantum gate for the quantum computing system based at least in part on the plurality of gate parameters.