Abstract: A hybrid computer comprising a quantum processor can be operated to perform a scalable comparison of high-entropy samplers. Performing a scalable comparison of high-entropy samplers can include comparing entropy and KL divergence of post-processed samplers. A hybrid computer comprising a quantum processor generates samples for machine learning. The quantum processor is trained by matching data statistics to statistics of the quantum processor. The quantum processor is tuned to match moments of the data.

Abstract: A superconducting circuit may include a transmission line having at least one transmission line inductance, a superconducting resonator, and a coupling capacitance that communicatively couples the superconducting resonator to the transmission line. The transmission line inductance may have a value selected to at least partially compensate for a variation in a characteristic impedance of the transmission line, the variation caused at least in part by the coupling capacitance. The coupling capacitance may be distributed along the length of the transmission line. A superconducting circuit may include a transmission line having at least one transmission line capacitance, a superconducting resonator, and a coupling inductance that communicatively couples the superconducting resonator to the transmission line. The transmission line capacitance may be selected to at least partially compensate for a variation in coupling strength between the superconducting resonator and the transmission line.

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: Collaborative filtering systems based on variational autoencoders (VAEs) are provided. VAEs may be trained on row-wise data without necessarily training a paired VAE on column-wise data (or vice-versa), and may optionally be trained via minibatches. The row-wise VAE models the output of the corresponding column-based VAE as a set of parameters and uses these parameters in decoding. In some implementations, a paired VAE is provided which receives column-wise data and models row-wise parameters; each of the paired VAEs may bind their learned column- or row-wise parameters to the output of the corresponding VAE. The paired VAEs may optionally be trained via minibatches. Unobserved data may be explicitly modelled. Methods for performing inference with such VAE-based collaborative filtering systems are also disclosed, as are example applications to search and anomaly detection.

Abstract: Achieving orthogonal control of non-orthogonal qubit parameters of a logical qubit allows for increasing the length of a qubit chain thereby increasing the effective connectivity of the qubit chain. A hybrid qubit is formed by communicatively coupling a dedicated second qubit to a first qubit. By tuning a programmable parameter of the second qubit of a hybrid qubit, an effective programmable parameter of the hybrid qubit is adjusted without affecting another effective programmable parameter of the hybrid qubit thereby achieving orthogonal control of otherwise non-orthogonal qubit parameters. The length of the logical qubit may thus be increased by communicatively coupling a plurality of such hybrid qubits together.

Abstract: A system and method of implementing finite element modeling on a quantum processor is discussed. A representation of a computational problem including a boundary value problem and problem grid points is received by one or more processors. The problem grid points are mapped to a Hilbert space of the qubits of the quantum processor. The boundary value problem is transformed into a problem Hamiltonian. Instructions are transmitted to the quantum processor to cause the quantum processor to evolve from an initial state to a final state based on the problem Hamiltonian. The wavefunction amplitudes of the final state are measured, and the wavefunction amplitudes of the final state are mapped onto the problem grid points based on the Hilbert space of the qubits.

Abstract: A user interface (UI), data structures and algorithms facilitate programming, analyzing, debugging, embedding, and/or modifying problems that are embedded or to be embedded on an analog processor (e.g., quantum processor), increasing computational efficiency and/or accuracy of problem solutions. The UI provides graph representations (e.g., source graph, target graph and correspondence therebetween) with nodes and edges which may map to hardware components (e.g., qubits, couplers) of the analog processor. Characteristics of solutions are advantageously represented spatially associated (e.g., overlaid or nested) with characteristics of a problem. Characteristics (e.g., bias state) may be represented by color, pattern, values, icons. Issues (e.g., broken chains) may be detected and alerts provided.

Abstract: A circuit can include a galvanic coupling of a coupler to a qubit by a segment of kinetic inductance material. The circuit can include a galvanic kinetic inductance coupler having multiple windings. The circuit can include a partially-galvanic coupler having multiple windings. The partially-galvanic coupler can include a magnetic coupling and a galvanic coupling. The circuit can include an asymmetric partially-galvanic coupler having a galvanic coupling and a first magnetic coupling to one qubit and a second magnetic coupling to a second qubit. The circuit can include a compact kinetic inductance qubit having a qubit body loop comprising a kinetic inductance material. A multilayer integrated circuit including a kinetic inductance layer can form a galvanic kinetic inductance coupling. A multilayer integrated circuit including a kinetic inductance layer can form at least a portion of a compact kinetic inductance qubit body loop.

Abstract: Quantum processors having qubits with tunable capacitance are provided. The qubits include Josephson junctions shunted by capacitors and are tunably coupled to capacitance loops such that the resonant frequencies of the qubits and capacitance loops avoid entanglement with each other. Methods for tuning the capacitance of such qubits by varying the coupler's coupling strength are provided. These methods include methods for calibrating qubits' capacitance.

Abstract: A technique for improving the performance of non-stoquastic quantum processors is provided. Clusters of qubits with correlated behavior are identified in a problem for processing by the quantum processor. Couplings between qubits in a common cluster are modified according to a transformation (for example, a gauge transformation) so that they evolve slower and thus their dynamics freeze out later (for example, by flipping anti-ferromagnetic couplings to ferromagnetic couplings). Couplings between qubits that do not belong to the common cluster may be flipped the other way (for example, from ferromagnetic couplings to anti-ferromagnetic couplings) to accelerate their dynamics. The quantum processor is evolved and the results are modified according to an inverse transformation.

Abstract: Computational systems implement problem solving using hybrid digital/quantum computing approaches. A problem may be represented as a problem graph which is larger and/or has higher connectivity than a working and/or hardware graph of a quantum processor. A quantum processor may be used determine approximate solutions, which solutions are provided as initial states to one or more digital processors which may implement classical post-processing to generate improved solutions. Techniques for solving problems on extended, more-connected, and/or “virtual full yield” variations of the processor's actual working and/or hardware graphs are provided. A method of operation in a computational system comprising a quantum processor includes partitioning a problem graph into sub-problem graphs, and embedding a sub-problem graph onto the working graph of the quantum processor. The quantum processor and a non-quantum processor-based device generate partial samples.

Abstract: Calibration techniques for devices of analog processors to remove time-dependent biases are described. Devices in an analog processor exhibit a noise spectrum that spans a wide range of frequencies, characterized by 1/f spectrum. Offset parameters are determined assuming only a given power spectral density. The algorithm determines a model for a measurable quantity of a device in an analog processor associated with a noise process and an offset parameter, determines the form of the spectral density of the noise process, approximates the noise spectrum by a discrete distribution via the digital processor, constructs a probability distribution of the noise process based on the discrete distribution and evaluates the probability distribution to determine optimized parameter settings to enhance computational efficiency.

Abstract: A quantum processor comprises a plurality of tiles, the plurality of tiles arranged in a first grid, and where a first tile of the plurality of tiles comprises a number of qubits (e.g., superconducting qubits). The quantum processor further comprises a shift register comprising at least one shift register stage communicatively coupled to a frequency-multiplexed resonant (FMR) readout, a qubit readout device, a plurality of digital-to-analog converter (DAC) buffer stages, and a plurality of shift-register-loadable DACs arranged in a second grid. The quantum processor may further include a transmission line comprising at least one transmission line inductance, a superconducting resonator, and a coupling capacitance that communicatively couples the superconducting resonator to the transmission line. A digital processor may program at least one of the plurality of shift-register-loadable DACs. Programming the first tile may be performed in parallel with programming a second tile of the plurality of tiles.

Abstract: A second problem Hamiltonian may replace a first problem Hamiltonian during evolution of an analog processor (e.g., quantum processor) during a first iteration in solving a first problem. This may be repeated during a second, or further successive iterations on the first problem, following re-initialization of the analog processor. An analog processor may evolve under a first non-monotonic evolution schedule during a first iteration, and second non-monotonic evolution schedule under second, or additional non-monotonic evolution schedule under even further iterations. A first graph and second graph may each be processed to extract final states versus a plurality of evolution schedules, and a determination made as to whether the first graph is isomorphic with respect to the second graph. An analog processor may evolve by decreasing a temperature of, and a set of quantum fluctuations, within the analog processor until the analog processor reaches a state preferred by a problem Hamiltonian.

Abstract: Computational systems and methods employ characteristics of a quantum processor determined or sampled between a start and an end of an annealing evolution per an annealing schedule. The annealing evolution can be reinitialized, reversed or continued after determination. The annealing evolution can be interrupted. The annealing evolution can be ramped immediately prior to or as part of determining the characteristics. The annealing evolution can be paused or not paused immediately prior to ramping. A second representation of a problem can be generated based at least in part on the determined characteristics from an annealing evolution performed on a first representation of the problem. The determined characteristics can be autonomously compared to an expected behavior, and alerts optionally provided and/or the annealing evolution optionally terminated based on the comparison. Iterations of annealing evolutions may be performed until an exit condition occurs.

Abstract: Systems and methods are described for operating a hybrid computing system using cluster contraction for converting large, dense input to reduced input that can be easily mapped into a quantum processor. The reduced input represents the global structure of the problem. Techniques involve partitioning the input variables into clusters and contracting each cluster. The input variables can be partitioned using an Unweighted Pair Group Method with Arithmetic Mean algorithm. The quantum processor returns samples based on the reduced input and the samples are expanded to correspond to the original input.

Abstract: Hybrid quantum-classical approaches for solving computational problems in which results from a quantum processor are combined with an exact method executed on a classical processor are described. Quantum processors can generate candidate solutions to a combinatorial optimization problem, but since quantum processors can be probabilistic, they are unable to certify that a solution is an optimal solution. A hybrid quantum-classical exact solver addresses this problem by combining outputs from a quantum annealing processor with a classical exact algorithm that is modified to exploit properties of the quantum computation. The exact method executed on a classical processor can be a Branch and Bound algorithm. A Branch and Bound algorithm can be modified to exploit properties of quantum computation including a) the sampling of multiple low-energy solutions by a quantum processor, and b) the embedding of solutions in a regular structure such as a native hardware graph of a quantum processor.

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: Generate an automorphism of the problem graph, determine an embedding of the automorphism to the hardware graph and modify the embedding of the problem graph into the hardware graph to correspond to the embedding of the automorphism to the hardware graph. Determine an upper-bound on the required chain strength. Calibrate and record properties of the component of a quantum processor with a digital processor, query the digital processor for a range of properties. Generate a bit mask and change the sign of the bias of individual qubits according to the bit mask before submitting a problem to a quantum processor, apply the same bit mask to the bit result. Generate a second set of parameters of a quantum processor from a first set of parameters via a genetic algorithm.

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.