Abstract: In a quantum processor some couplers couple a given qubit to a nearest neighbor qubit (e.g., vertically and horizontally in an ordered 2D array), other couplers couple to next-nearest neighbor qubits (e.g., diagonally in the ordered 2D array). Couplers may include half-couplers, to selectively provide communicative coupling between a given qubit and other qubits, which may or may not be nearest or even next-nearest-neighbors. Tunable couplers selective mediate communicative coupling. A control system may impose a connectivity on a quantum processor, different than an “as designed” or “as manufactured” physical connectivity. Imposition may be via a digital processor processing a working or updated working graph, to map or embed a problem graph. A set of exclude qubits may be created from a comparison of hardware and working graphs. An annealing schedule may adjust a respective normalized inductance of one or more qubits, for instance to exclude certain qubits.

Abstract: Topologies for analog computing systems are provided. Qubits in the topology are grouped into cells, and cells are coupled to adjacent cells by inter-cell couplers. At least some cells are coupled to non-adjacent cells via long-range couplers. Long-range couplers may be arranged into coverings so that certain sets of qubits within a covering region may be coupled with a reduced number of couplers. Each cell within a covering region without a long-range coupler may be proximate to a cell with a long range coupler so that each cell within the covering region is no more than a certain coupling distance away from a long-range coupler. Long-range couplers may couple over a greater physical distance than inter-cell couplers. Long-range couplers may couple to qubits over a larger coupling region, and may extend across multiple crossing regions between qubits.

Abstract: In a quantum processor some couplers couple a given qubit to a nearest neighbor qubit (e.g., vertically and horizontally in an ordered 2D array), other couplers couple to next-nearest neighbor qubits (e.g., diagonally in the ordered 2D array). Couplers may include half-couplers, to selectively provide communicative coupling between a given qubit and other qubits, which may or may not be nearest or even next-nearest-neighbors. Tunable couplers selective mediate communicative coupling. A control system may impose a connectivity on a quantum processor, different than an “as designed” or “as manufactured” physical connectivity. Imposition may be via a digital processor processing a working or updated working graph, to map or embed a problem graph. A set of exclude qubits may be created from a comparison of hardware and working graphs. An annealing schedule may adjust a respective normalized inductance of one or more qubits, for instance to exclude certain qubits.

Abstract: 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.

Abstract: 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.

Abstract: In a quantum processor some couplers couple a given qubit to a nearest neighbor qubit (e.g., vertically and horizontally in an ordered 2D array), other couplers couple to next-nearest neighbor qubits (e.g., diagonally in the ordered 2D array). Couplers may include half-couplers, to selectively provide communicative coupling between a given qubit and other qubits, which may or may not be nearest or even next-nearest-neighbors. Tunable couplers selective mediate communicative coupling. A control system may impose a connectivity on a quantum processor, different than an “as designed” or “as manufactured” physical connectivity. Imposition may be via a digital processor processing a working or updated working graph, to map or embed a problem graph. A set of exclude qubits may be created from a comparison of hardware and working graphs. An annealing schedule may adjust a respective normalized inductance of one or more qubits, for instance to exclude certain qubits.

Abstract: Systems and methods for employing macroscopic resonant tunneling operations in quantum processors are described. New modes of use for quantum processor architectures employ probe qubits to determine energy eigenvalues of a problem Hamiltonian through macroscopic resonant tunneling operations. A dedicated probe qubit design that may be added to quantum processor architectures is also described. The dedicated probe qubit enables improved performance of macroscopic resonant tunneling operations and, consequently, improved performance of the new modes of use described.

Abstract: SQUIDs may detect local magnetic fields. SQUIDS of varying sizes, and hence sensitivities may detect different magnitudes of magnetic fields. SQUIDs may be oriented to detect magnetic fields in a variety of orientations, for example along an orthogonal reference frame of a chip or wafer. The SQUIDS may be formed or carried on the same chip or wafer as a superconducting processor (e.g., a superconducting quantum processor). Measurement of magnetic fields may permit compensation, for example allowing tuning of a compensation field via a compensation coil and/or a heater to warm select portions of a system. A SQIF may be implemented as a SQUID employing an unconventional grating structure. Successful fabrication of an operable SQIF may be facilitated by incorporating multiple Josephson junctions in series in each arm of the unconventional grating structure.

Abstract: 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.

Abstract: SQUIDs may detect local magnetic fields. SQUIDS of varying sizes, and hence sensitivities may detect different magnitudes of magnetic fields. SQUIDs may be oriented to detect magnetic fields in a variety of orientations, for example along an orthogonal reference frame of a chip or wafer. The SQUIDS may be formed or carried on the same chip or wafer as a superconducting processor (e.g., a superconducting quantum processor). Measurement of magnetic fields may permit compensation, for example allowing tuning of a compensation field via a compensation coil and/or a heater to warm select portions of a system. A SQIF may be implemented as a SQUID employing an unconventional grating structure. Successful fabrication of an operable SQIF may be facilitated by incorporating multiple Josephson junctions in series in each arm of the unconventional grating structure.

Abstract: 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.

Abstract: A quantum processor is operable as a universal adiabatic quantum computing system. The quantum processor includes physical qubits, with at least a first and second communicative coupling available between pairs of qubits via an in-situ tunable superconducting capacitive coupler and an in-situ tunable superconducting inductive coupler, respectively. Tunable couplers provide diagonal and off-diagonal coupling. Compound Josephson junctions (CJJs) of the tunable couplers are responsive to a flux bias to tune a sign and magnitude of a sum of a capacitance of a fixed capacitor and a tunable capacitance which is mediated across a pair of coupling capacitors. The qubits may be hybrid qubits, operable in a flux regime or a charge regime. Qubits may include a pair of CJJs that interrupt a loop of material and which are separated by an island of superconducting material which is voltage biased with respect to a qubit body.

Abstract: Quantum annealing may include applying and gradually removing disorder terms to qubits of a quantum processor, for example superconducting flux qubits of a superconducting quantum processor. A problem Hamiltonian may be established by applying control signals to the qubits, an evolution Hamiltonian established by applying disorder terms, and annealing by gradually removing the disorder terms. Change in persistent current in the qubits may be compensated. Multipliers may mediate coupling between various qubits and a global signal line, for example by applying respective scaling factors. Two global signal lines may be arranged in an interdigitated pattern to couple to respective qubits of a communicatively coupled pair of qubits. Pairs of qubits may be communicatively isolated and used to measure a response of one another to defined signals.

Abstract: SQUIDs may detect local magnetic fields. SQUIDS of varying sizes, and hence sensitivities may detect different magnitudes of magnetic fields. SQUIDs may be oriented to detect magnetic fields in a variety of orientations, for example along an orthogonal reference frame of a chip or wafer. The SQUIDS may be formed or carried on the same chip or wafer as a superconducting processor (e.g., a superconducting quantum processor). Measurement of magnetic fields may permit compensation, for example allowing tuning of a compensation field via a compensation coil and/or a heater to warm select portions of a system. A SQIF may be implemented as a SQUID employing an unconventional grating structure. Successful fabrication of an operable SQIF may be facilitated by incorporating multiple Josephson junctions in series in each arm of the unconventional grating structure.

Abstract: Systems and methods for improving calibration procedures in a quantum processor architecture are described. For example, a dedicated calibration signal source is built into the architecture of the quantum processor for use during calibration. A single calibration signal source is communicatively coupled to many devices in the quantum processor architecture to provide an absolute calibration signal against which various parameters, responses, and/or behaviors of the many devices may be calibrated, either in series or in parallel. The use of a calibration signal source may reduce the time required to calibrate the elements of a quantum processor and/or improve the accuracy/precision of such calibrations.

Abstract: Systems and methods for improving the performance of dilution refrigeration systems are described. Filters and traps employed in the helium circuit of a dilution refrigerator may be modified to improve performance. Some traps may be designed to harness cryocondensation as opposed to cryoadsorption. A cryocondensation trap employs a cryocondensation surface having a high thermal conductivity and a high specific heat with a binding energy that preferably matches at least one contaminant but does not match helium. Multiple traps may be coupled in series in the helium circuit, with each trap designed to trap a specific contaminant or set of contaminants. Both cryocondensation and cryoadsorption may be exploited among multiple traps.

Abstract: 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.

Abstract: Iterative approaches to quantum computation are described. Incongruities in the behavior of the various individual elements in a quantum processor may be managed by establishing a set of equivalent configurations for the elements of the quantum processor. The quantum processor is programmed and operated using each equivalent configuration to determine a set of solutions. The solutions are evaluated to determine a preferred solution that best satisfies at least one criterion. Furthermore, thermodynamic effects from operating a quantum processor at non-absolute zero temperature can cause the ground state to be the most probable state into which the system will settle. By running multiple iterations the ground state may be identified as the state with the most frequent reoccurrences. Alternatively, the energy of each unique state may be calculated and the state that corresponds to the lowest energy may be returned as the solution to the problem.

Abstract: A ladder structure is ferromagnetically coupled to a first qubit where the ladder structure has a monostable energy potential in use, such that the first qubit and the ladder structure effectively operate as a single qubit. The ladder structure and first qubit may be coupled via a superconducting flux coupler. The ladder structure may be a chain of at least two ferromagnetically coupled ladder elements. A value for each ladder element may be less than about 1.

Abstract: Iterative approaches to quantum computation are described. Incongruities in the behavior of the various individual elements in a quantum processor may be managed by establishing a set of equivalent configurations for the elements of the quantum processor. The quantum processor is programmed and operated using each equivalent configuration to determine a set of solutions. The solutions are evaluated to determine a preferred solution that best satisfies at least one criterion. Furthermore, thermodynamic effects from operating a quantum processor at non-absolute zero temperature can cause the ground state to be the most probable state into which the system will settle. By running multiple iterations the ground state may be identified as the state with the most frequent reoccurrences. Alternatively, the energy of each unique state may be calculated and the state that corresponds to the lowest energy may be returned as the solution to the problem.