Abstract: A quantum computing system includes a cryogenic chamber and an integrated circuit located in the chamber. The integrated circuit includes a substrate, a qubit formed on the substrate, and a dissipative element that is formed on the substrate and coupled to the qubit. When the qubit is tuned to a first flux value, the integrated circuit is enabled to perform quantum-computation operations on a set of quantum states of the qubit. The quantum states include a ground state and an excited state. When the qubit is tuned to a second flux value, the qubit is enabled to transfer energy associated with the excited state from the qubit to the dissipative element. Upon the energy transfer, the qubit is transitioned to the ground state. The dissipative element is enabled to dissipate the transferred energy to a portion of the substrate.

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.

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.

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.

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.