D-Wave Systems Inc.

1372934 B.c. Ltd

Mark H Volkmann

Jed D Whittaker

Andrew Joseph Berkley

Loren J Swenson

George E G Sterling

Paul I Bunyk

Emile M Hoskinson

Peter D Spear

Christopher B Rich

Ilya V Perminov

Reza Molavi

Mark W Johnson

Colin C Enderud

Abraham J Evert

Catia Baron Aznar

Michael S Babcock

Mauricio Reis Filho

Min Jan Tsai

A method of generating a coupling gate between qubits and a superconducting integrated circuit providing a pulse source are discussed. The method includes energizing a power line connected to a pulse source, applying a signal to a control line in communication with a coupler, the coupler in communication between the two qubits, and applying a second signal to a control line in communication with a resonator. The method further includes inducing a tone on a transmission line that selectively communicates with the resonator to bias the resonator, the resonator coupling a signal to the pulse source in combination with the power line, and applying a third signal to a pulse source control line in communication with the pulse source, the pulse source applying a pulse to the coupler in response to the third signal to couple the two qubits for a duration of the coupling gate.

Systems and methods for qubit control

A digital processor simulates a quantum computing system by implementing a QPU model including a set of representation models and a device connectivity representation to simulate a quantum processor design or a physical quantum processor. The digital processor receives an analog waveform and generates a digital waveform representation comprising a set of waveform values that correspond to biases applied to programmable devices in a quantum processor. The digital processor selects a subset of waveform values based on channels in the device connectivity representation. The digital processor implements a representation model to compute a response based on the waveform values and a plurality of physical parameter values, the physical parameters characterizing a programmable device in a quantum processor. The device connectivity representation can be generated from a design implementation, validated against a set of rules, and adjusted to change the device connectivity representation until all of the rules are passed.

Systems and methods for simulating a quantum processor

Systems and methods for capacitance tuning of devices in quantum processors are described. One implementation is a quantum processor with a first current path having a first loop, a Josephson structure with at least one Josephson junction interrupting the first loop, a second current path connected to the first current path, and a flux bias. The second current path has a first node spaced from a second node, a capacitor separating the first node and the second node, and a voltage gain tuner, the voltage gain tuner being inductively coupled to the inductance of the first current path. The flux bias is coupled to the voltage gain tuner and controls the voltage gain tuner to vary a voltage ratio between the first node and the second node, thereby influencing the capacitance of the first current path.

Systems and methods for tuning capacitance in quantum devices

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. A low-frequency current bias may be used at room temperature to identify the presence of a DC short, an open, and/or an unexpected resistance in a superconducting resonator.

Systems and methods for addressing devices in a superconducting circuit

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.

Systems and methods for coupling a superconducting transmission line to an array of resonators

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.

Kinetic inductance for couplers and compact qubits

A superconducting input and/or output system employs at least one microwave superconducting resonator. The microwave superconducting resonator(s) may be communicatively coupled to a microwave transmission line. Each microwave superconducting resonator may include a first and a second DC SQUID, in series with one another and with an inductance (e.g., inductor), and a capacitance in parallel with the first and second DC SQUIDs and inductance. Respective inductive interfaces are operable to apply flux bias to control the DC SQUIDs. The second DC SQUID may be coupled to a Quantum Flux Parametron (QFP), for example as a final element in a shift register. A superconducting parallel plate capacitor structure and method of fabricating such are also taught.

Method of fabricating a superconducting parallel plate capacitor

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.

Dynamical isolation of a cryogenic processor

A superconducting readout system employing a microwave transmission line, and a microwave superconducting resonator communicatively coupled to the microwave transmission line, and including a superconducting quantum interference device (SQUID), may be advantageously calibrated at least in part by measuring a resonant frequency of the microwave superconducting resonator in response to a flux bias applied to the SQUID, measuring a sensitivity of the resonant frequency in response to the flux bias, and selecting an operating frequency and a sensitivity of the microwave superconducting resonator based at least in part on a variation of the resonant frequency as a function of the flux bias. The flux bias may be applied to the SQUID by an interface inductively coupled to the SQUID. Calibration of the superconducting readout system may also include determining at least one of a propagation delay, a microwave transmission line delay, and a microwave transmission line phase offset.

Systems and methods for operation of a frequency multiplexed resonator input and/or output for a superconducting device

Systems and methods are described to accurately extract device parameters and optimize the design of macroscopic superconducting structures, for example qubits. This method presents the advantage of reusing existing plaquettes to simulate different processor topologies. The physical elements of a qubits are extracted via plurality of plaquettes. Each plaquette contains at least one physical element of the qubit design and has two ports on each side. Each plaquette is concatenated to at least one other plaquette via two ports. The values of inductance (L), capacitance (C) and mutual inductance (M) and quantum critical point of the qubit design can be computed. Changing the physical elements of the qubit design and iterating the method allows to effortlessly refine the qubit design.

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Mark H Volkmann