Abstract: A system, comprising a superconducting integrated circuit and a controller, may be operated to apply, for each power level of a sequence of discrete power levels on a respective one of a plurality of power lines, one or more pulses via a respective one of a plurality of addressing lines to a respective compound Josephson junction of each of a plurality of flux storage devices of the superconducting integrated circuit to cause each of the plurality of flux storage devices to reset. Power levels may be based at least in part on an estimated worst-case asymmetry between Josephson junctions of the compound Josephson junctions. The system may be operated to partition the plurality of addressing lines into groups, and apply a respective sequence of pulses to each addressing line of each pairwise combination of groups to cause one or more of the plurality of flux storage devices to reset.

Abstract: Methods and systems for calibrating quantum processors are discussed. A model of a portion of the processor to be calibrated has one or more determinable parameters and an uncertainty for the determinable parameter(s). A measurement procedure is iteratively performed by selecting a subset of possible measurements and generating predicted measurement outcomes and predicted uncertainties for the determinable parameter for each measurement in the subset of possible measurements. Based on the predicted reduction in uncertainty for the determinable parameter, one or more measurements is selected. Instructions are transmitted to the quantum processor to perform the selected measurements, and the results are returned to update the model of the portion of the processor to be calibrated. Once a termination criteria is met, a calibrated value is generated for the determinable parameter. Compensating signals can be applied to devices of the quantum processor to calibrate the devices.

Abstract: Superconducting integrated circuits may advantageously employ superconducting resonators coupled to a microwave transmission line to efficiently address superconducting flux storage devices. In an XY-addressing scheme, a global flux bias may be applied to a number of superconducting flux storage devices via a low-frequency address line, and individual superconducting flux storage devices addressed via application of high-frequency pulses via resonators driven by the microwave transmission line. Frequency multiplexing can be employed to provide signals to two or more resonators. A low-frequency current bias may be combined with a high-frequency current in one or more superconducting resonators to provide Z-addressing. A low-frequency current bias may be combined with a high-frequency current in one or more superconducting resonators to eliminate a flux bias line.

Abstract: A device is dynamically isolated via a broadband switch that includes a plurality of cascade elements in series, wherein each cascade element comprises a first set of SQUIDs in series, a matching capacitor, and a second set of SQUIDs in series. The broadband switch is set to a passing state via flux bias lines during programming and readout of the device and set to a suppression state during device's calculation to reduce operation errors at the device. A device is electrically isolated from high-frequencies via an unbiased broadband switch. A device is coupled to a tunable thermal bath that includes a broadband switch.

Abstract: Devices, methods and articles advantageously allow communications between qubits to provide an architecture for universal adiabatic quantum computation. The architecture includes a first coupled basis A1B1 and a second coupled basis A2B2 that does not commute with the first basis A1B1.

Abstract: Approaches useful to operation of scalable processors with ever larger numbers of logic devices (e.g., qubits) advantageously take advantage of QFPs, for example to implement shift registers, multiplexers (i.e., MUXs), de-multiplexers (i.e., DEMUXs), and permanent magnetic memories (i.e., PMMs), and the like, and/or employ XY or XYZ addressing schemes, and/or employ control lines that extend in a “braided” pattern across an array of devices. Many of these described approaches are particularly suited for implementing input to and/or output from such processors. Superconducting quantum processors comprising superconducting digital-analog converters (DACs) are provided. The DACs may use kinetic inductance to store energy via thin-film superconducting materials and/or series of Josephson junctions, and may use single-loop or multi-loop designs. Particular constructions of energy storage elements are disclosed, including meandering structures.

Abstract: A device is dynamically isolated via a broadband switch that includes a plurality of cascade elements in series, wherein each cascade element comprises a first set of SQUIDs in series, a matching capacitor, and a second set of SQUIDs in series. The broadband switch is set to a passing state via flux bias lines during programming and readout of the device and set to a suppression state during device's calculation to reduce operation errors at the device. A device is electrically isolated from high-frequencies via an unbiased broadband switch. A device is coupled to a tunable thermal bath that includes a broadband switch.

Abstract: Approaches useful to operation of scalable processors with ever larger numbers of logic devices (e.g., qubits) advantageously take advantage of QFPs, for example to implement shift registers, multiplexers (i.e., MUXs), de-multiplexers (i.e., DEMUXs), and permanent magnetic memories (i.e., PMMs), and the like, and/or employ XY or XYZ addressing schemes, and/or employ control lines that extend in a “braided” pattern across an array of devices. Many of these described approaches are particularly suited for implementing input to and/or output from such processors. Superconducting quantum processors comprising superconducting digital-analog converters (DACs) are provided. The DACs may use kinetic inductance to store energy via thin-film superconducting materials and/or series of Josephson junctions, and may use single-loop or multi-loop designs. Particular constructions of energy storage elements are disclosed, including meandering structures.

Abstract: A hybrid computing system for solving a computational problem includes a digital processor, a quantum processor having qubits and coupling devices that together define a working graph of the quantum processor, and at least one nontransitory processor-readable medium communicatively coupleable to the digital processor which stores at least one of processor-executable instructions or data. The digital processor receives a computational problem, and programs the quantum processor with a first set of bias fields and a first set of coupling strengths. The quantum processor generates samples as potential solutions to an approximation of the problem. The digital processor updates the approximation by determining a second set of bias fields based at least in part on the first set of bias fields and a first set of mean fields that are based at least in part on the first set of samples and coupling strengths of one or more virtual coupling devices.

Abstract: An analog computing system having a qubit which is provided with inductors positioned near to the qubit's Josephson junctions and inductors positioned far from the qubit's Josephson junctions. The near inductors exhibit capacitance-reducing behavior and the far inductors exhibit capacitance-increasing behavior as their respective inductances are increased. Near and far inductors can be tuned to homogenize the capacitance of the qubit across a range of programmable states based on predicted and target capacitance for the qubit. The inductors may be tuned to homogenize both capacitance and inductance.

Abstract: A device is dynamically isolated via a broadband switch that includes a plurality of cascade elements in series, wherein each cascade element comprises a first set of SQUIDs in series, a matching capacitor, and a second set of SQUIDs in series. The broadband switch is set to a passing state via flux bias lines during programming and readout of the device and set to a suppression state during device's calculation to reduce operation errors at the device. A device is electrically isolated from high-frequencies via an unbiased broadband switch. A device is coupled to a tunable thermal bath that includes a broadband switch.

Abstract: Analog processors for solving various computational problems are provided. Such analog processors comprise a plurality of quantum devices, arranged in a lattice, together with a plurality of coupling devices. The analog processors further comprise bias control systems each configured to apply a local effective bias on a corresponding quantum device. A set of coupling devices in the plurality of coupling devices is configured to couple nearest-neighbor quantum devices in the lattice. Another set of coupling devices is configured to couple next-nearest neighbor quantum devices. The analog processors further comprise a plurality of coupling control systems each configured to tune the coupling value of a corresponding coupling device in the plurality of coupling devices to a coupling. Such quantum processors further comprise a set of readout devices each configured to measure the information from a corresponding quantum device in the plurality of quantum devices.

Abstract: A quantum processor performs input and output which may be performed synchronously. The quantum processor executes a problem to generate a classical output state, which is read out at least partially by an I/O system. The I/O system also transmits a classical input state to by the I/O system, which may include the same qubit-proximate devices used for read-out. The classical input state is written to the qubits, and the quantum processor executes based on the classical input state (e.g., by performing reverse annealing to transform the classical input state to quantum state).

Abstract: A hybrid processor includes a classical (digital) processor and a quantum processor and implements a calibration procedure to calibrate devices in the quantum processor. Parameter measurements are defined as vertices in a directed acyclic graph. Dependencies between measurements are defined as directed edges between vertices. The calibration procedure orders the vertices, respecting the order of the dependencies while at least attempting to reduce the time needed to perform all the measurements. The calibration procedure provides a level of abstraction to allow non-expert users to use the calibration procedure. Each vertex has a set of attributes defining the status of the measurement, time of the measurement and value of the measurement.

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 device is dynamically isolated via a broadband switch that includes a plurality of cascade elements in series, wherein each cascade element comprises a first set of SQUIDs in series, a matching capacitor, and a second set of SQUIDs in series. The broadband switch is set to a passing state via flux bias lines during programming and readout of the device and set to a suppression state during device's calculation to reduce operation errors at the device. A device is electrically isolated from high-frequencies via an unbiased broadband switch. A device is coupled to a tunable thermal bath that includes a broadband switch.

Abstract: A superconducting integrated circuit is fabricated by depositing a ground plane to at least partially overlie a substrate, depositing an insulating layer to at least partially overlie the ground plane, depositing a superconducting layer to at least partially overlie the insulating layer, and forming a superconducting feature in the superconducting layer. An inductance of the superconducting feature is tunable by adjusting a bias current in the ground plane. The ground plane is electrically communicatively coupleable to an electrical ground. Depositing a ground plane includes depositing a first superconducting material to at least partially overlie the substrate and depositing a second superconducting material to at least partially overlie the first superconducting material. A second critical current density of the second superconducting material is higher than a first critical current density of the first superconducting material.

Abstract: Devices, methods and articles advantageously allow communications between qubits to provide an architecture for universal adiabatic quantum computation. The architecture includes a first coupled basis A1B1 and a second coupled basis A2B2 that does not commute with the first basis A1B1.

Abstract: Methods for reducing errors in calibrated devices comprise detecting outliers, self-checking consistency of measurements, tuning device controls to target values, and absolutely calibrating devices via a first standard and cross-checking the results via a second standard. The first standard may be a calibrated current and the second calibration standard may be a calibrated frequency. A calibrated frequency may be a microwave signal applied to the body of a qubit. Qubit annealing controls can quickly lower and raise the tunnel barrier to measures the oscillation frequency of the qubit between two potential wells.

Abstract: Analog processors for solving various computational problems are provided. Such analog processors comprise a plurality of quantum devices, arranged in a lattice, together with a plurality of coupling devices. The analog processors further comprise bias control systems each configured to apply a local effective bias on a corresponding quantum device. A set of coupling devices in the plurality of coupling devices is configured to couple nearest-neighbor quantum devices in the lattice. Another set of coupling devices is configured to couple next-nearest neighbor quantum devices. The analog processors further comprise a plurality of coupling control systems each configured to tune the coupling value of a corresponding coupling device in the plurality of coupling devices to a coupling. Such quantum processors further comprise a set of readout devices each configured to measure the information from a corresponding quantum device in the plurality of quantum devices.