Systems, methods and apparatus for active compensation of quantum processor elements

摘要

Apparatus and methods enable active compensation for unwanted discrepancies in the superconducting elements of a quantum processor. A qubit may include a primary compound Josephson junction (CJJ) structure, which may include at least a first secondary CJJ structure to enable compensation for Josephson junction asymmetry in the primary CJJ structure. A qubit may include a series LC-circuit coupled in parallel with a first CJJ structure to provide a tunable capacitance. A qubit control system may include means for tuning inductance of a qubit loop, for instance a tunable coupler inductively coupled to the qubit loop and controlled by a programming interface, or a CJJ structure coupled in series with the qubit loop and controlled by a programming interface.

主权项

1. A quantum processor comprising:
a first qubit having a first characteristic associated with a parameter; a second qubit having a second characteristic associated with the parameter, wherein the first characteristic of the first qubit is different from the second characteristic of the second qubit; a coupling system selectively configurable to provide communicative coupling between the first qubit and the second qubit; and at least one device that is selectively operable to tune the parameter of the first qubit such that the first characteristic of the first qubit matches the second characteristic of the second qubit, wherein the parameter is capacitance, and the first qubit is a superconducting qubit and the second qubit is a superconducting qubit, the first and the second qubits each comprising: a qubit loop formed by a first superconducting current path; a first compound Josephson junction structure formed by a first pair of parallel superconducting current paths, wherein the first compound Josephson junction structure interrupts the qubit loop, and wherein each superconducting current path in the first pair of parallel superconducting current paths is interrupted by at least one Josephson junction; and a series LC-circuit coupled in parallel with the first compound Josephson junction structure through a superconducting current path, wherein the series LC-circuit realizes a tunable capacitance.