Abstract: A superconducting circuit comprises a first and second magnetic-flux-tunable elements. Each of these has a respective flux-sensitive part. First and second current-driven superconductive on-chip flux bias lines are provided. Each of these passes adjacent to the flux-sensitive part of the respective magnetic-flux-tunable element. A first plurality of superconductive stray current paths exists adjacent to the first magnetic-flux-tunable element. A second plurality of superconductive stray current paths exist adjacent to the second magnetic-flux-tunable element. The superconductive stray current paths distribute stray currents originating from the flux line of the other magnetic-flux-tunable element into a respective plurality of stray currents around the respective magnetic-flux-tunable element. This way the stray currents are kept from changing the electric characteristics of the respective magnetic-flux-tunable element.

Abstract: The invention is generally related to the field of quantum computing and particularly to a tunable resonator-resonator coupling circuit that provides both direct and indirect couplings between linear or nonlinear resonators. The indirect coupling is provided by using a tunable coupling element that comprises two ungrounded superconducting islands. Since the superconducting islands are ungrounded, it is possible to provide different signs of coupling frequencies for the resonators and the superconducting islands, which in turn allows the interaction between the first and second resonators to be controlled more efficiently. Moreover, the design, calibration, and operation of the circuit with such a tunable coupling element are significantly easier and simpler compared to the existing analogues, while providing the same or even better performance. A quantum computing apparatus using one or more such circuits is also provided.

Abstract: An electronic device for storing, controlling and manipulating electron or hole spin based semiconductor qubits, the device including an electrically insulating layer and on a front face of the insulating layer, a trapping structure for electrons or holes which includes: a channel portion including at least one layer portion of semiconductor material, as well as a plurality of gates distributed for trapping at least one electron or hole in the channel portion, and on the back side of the insulating layer, an electrical track extending parallel to the insulating layer, for generating an oscillating magnetic field acting on the at least one electron or hole trapped in the trapping structure.

Abstract: A device for generating a qubit control signal includes: a first signal envelope generator circuit including a first multiple of signal sources, in which an output of each signal source of the first multiple of signal sources is combined to provide a first cumulative output; and a first mixer circuit coupled to the first signal envelope generator circuit, in which the first cumulative output is coupled to a first input of the first mixer circuit, and an output of the first mixer circuit includes a first qubit control signal.

Abstract: One or more systems, devices and/or methods of use provided herein relate to a device that can provide bandwidth and/or saturation power to amplify a plurality of readout frequencies or to convert one or more frequencies. In quantum technology, the one or more systems, devices and/or methods of use provided herein can be employed to simultaneously readout a plurality of qubit resonators. A device can comprise a Josephson parametric converter device comprising a Josephson ring modulator having a pair of nodes, and an impedance matching circuit network operatively connected across the pair of nodes. The device can be separately operable in an amplification mode or in a conversion mode.

Abstract: A solid state cooler device is disclosed that comprises a first normal metal pad, a first aluminum layer and a second aluminum layer disposed on the first normal metal pad and separated from one another by a gap, a first aluminum oxide layer formed on the first aluminum layer, and a second aluminum oxide layer formed on the second aluminum layer, and a first superconductor pad disposed on the first aluminum oxide layer and a second superconductor pad disposed on the second aluminum oxide layer. The device further comprises a first conductive pad coupled to the first superconductor pad, and a second conductive pad coupled to the second superconductor pad, wherein hot electrons are removed from the first normal metal pad when a bias voltage is applied between the first conductive pad and the second conductive pad.

Abstract: One or more systems, devices and/or methods of use provided herein relate to a device that can facilitate selective switching between band pass and band stop filter modes and/or can provide reflectionless or near reflectionless function. A device can comprise a filter circuit coupled between a pair of ports and comprising a direct current superconducting quantum interference device (DC SQUID), wherein the filter circuit is selectively activatable by varying the inductance of the DC SQUID. Applying flux bias to the DC SQUID can allow for the switching between the band pass and band stop filter modes.

Abstract: Shift register elements of a phase-mode bit-addressable sensing register sample varied AC or DC bias values provided to operational RQL circuitry on the RQL IC via clock resonators or DC bias lines. The shift register can be constructed of phase-mode D flip-flops and JTLs as data and clock lines. A method of using the sensing register includes shifting in a data bit pattern while a bias parameter (e.g., AC amplitude, DC value, or phase) is set to a nominal value; stopping the logical clock that controls the shifting of values through the sensing register, varying the bias parameter value, inputting one assertion SFQ pulse or reciprocal pulse pair into the logical clock, restoring the bias parameter to the nominal value, restarting the logical clock to shift out an output data bit pattern, and observing the output data bit pattern to determine the effect of the bias parameter value change.

Abstract: Parametrically pumped four-wave mixing is a key building block for many developments in the field of superconducting quantum information processing. However, undesired frequency shifts such as Kerr, cross-Ken and Stark shifts inherent with four-wave mixing, lead to difficulties in tuning up the desired parametric processes and, for certain applications, severely limit the fidelities of the resulting operations. Some embodiments include a Josephson four-wave mixing device consisting of a SQUID transmon coupled to a half-flux biased SNAIL transmon, a.k.a. capacitively shunted flux qubit. When the two transmon have matching frequencies, an interference effect cancels the negative Kerr of the SQUID transmon with the positive Kerr of the SNAIL transmon while preserving parametric four-wave mixing capabilities.

Abstract: A superconducting circuit comprises a resonator and a Josephson junction. The resonator comprises an inductor and a capacitor. The inductor comprises a first terminal and a second terminal. The second terminal of the inductor is electrically coupled to a first terminal of the capacitor. A second terminal of the capacitor is electrically coupled to a first terminal of the Josephson junction. The terminal shared by the inductor and the capacitor is configured to be electrically coupled to an alternating current (AC) voltage source having a particular frequency and particular phase. The inductance of the inductor and the capacitance of the capacitor are selected to cause the resonator to resonate at a frequency and a phase that substantially match the particular frequency and the particular phase, respectively, of the AC voltage source to facilitate switching a state of the Josephson junction via a single flux quantum (SFQ) pulse.

Abstract: According to one embodiment, a coupler includes first to fourth capacitors, first and second inductors, and a first Josephson junction. The first capacitor includes a first capacitor end portion and a first capacitor other-end portion. The first inductor includes a first inductor end portion, and a first inductor other-end portion. The second inductor includes a second inductor end portion, and a second inductor other-end portion. The first Josephson junction includes a first Josephson junction end portion, and a first Josephson junction other-end portion. A space is surrounded with the first inductor, the second inductor, and the first Josephson junction. The third capacitor includes a third capacitor end portion, and a third capacitor other-end portion. The fourth capacitor includes a fourth capacitor end portion, and a fourth capacitor other-end portion.

Abstract: A superconducting AC switch system includes a switch network configuration comprising a Josephson junction (JJ) coupled to a transmission line having a transmission line impedance, and a magnetic field generator that is configured to switch from inducing a magnetic field in a plane of the JJ, and providing no magnetic field in the plane of the JJ. An AC input signal applied at an input of the switch network configuration is passed through to an output of the switch network configuration in a first magnetic state, and substantially reflected back to the input of the switch network configuration in a second magnetic state. The first magnetic state is one of inducing and not inducing a magnetic field in a plane of the JJ, and the second magnetic state is the other of inducing and not inducing a magnetic field in a plane of the JJ.

Abstract: There is described herein a topologically protected quantum circuit with superconducting qubits and method of operation thereof. The circuit comprises a plurality of physical superconducting qubits and a plurality of coupling devices interleaved between pairs of the physical superconducting qubits. The coupling devices comprise at least one ?-Josephson junction, wherein a Josephson phase ?0 of the ?-Josephson junction is non-zero in a ground state, the coupling devices have a Josephson energy EJ?, the physical superconducting qubits have a Josephson energy EJq, and the circuit operates in a topological regime when E J ? q 2 > - E J ? ? ? cos ? ? 0 > E J ? q 3 .

Abstract: A qubit structure includes a first fluxonium qubit having a first Josephson Junction (JJ) in parallel with a first capacitor and a first superconducting inductor. A second fluxonium qubit includes a second JJ in parallel with a second capacitor and a second superconducting inductor, coupled in series with the first fluxonium qubit. A third capacitor is coupled in parallel to the series first and second fluxonium qubits.

Abstract: Systems and methods are provided for coupling two qubits. A first persistent current qubit is fabricated with a first superconducting loop interrupted by a first Josephson junction isolated by a first inductor and a second inductor from a second Josephson junction. A second persistent current qubit is fabricated with a second superconducting loop interrupted by a third Josephson junction isolated by a third inductor and a fourth inductor from a fourth Josephson junction. Nodes defined by the Josephson junctions of the first qubit and their neighboring inductors are connected to corresponding nodes defined by the third Josephson junction and the third inductor via a first capacitor, with one pair of connections swapped such that the nodes are not connected to their respective corresponding nodes.

Abstract: Trap circuits for use with superconducting integrated circuits having capacitively-coupled resonant clock networks are described. An example superconducting integrated circuit (IC) includes a clock structure coupled: (1) to a first Josephson junction (JJ) via a first capacitor, where the first capacitor is configured to receive a clock signal via the clock structure and couple a first bias current to the first JJ, and (2) to a second JJ via a second capacitor, where the second capacitor is configured to receive a clock signal via the clock structure and couple a second bias current to the second JJ. The superconducting IC further includes a trap circuit coupled between the first capacitor and the first JJ, where the trap circuit is configured to attenuate any signals generated by a triggering of the first JJ to reduce crosstalk between the first JJ and the second JJ.

Abstract: Systems and techniques that facilitate entanglement via driving dark modes are provided. In various embodiments, a method can comprise accessing a first multi-mode qubit and a second multi-mode qubit. In various cases, the first multi-mode qubit can be coupled to the second multi-mode qubit by a mode-selective coupler. In various aspects, the method can further comprise exciting a dark mode of the first multi-mode qubit. In various cases, the exciting the dark mode can entangle the first multi-mode qubit with the second multi-mode qubit.

Abstract: A device includes: a plurality of qubits arranged in a two-dimensional array and a plurality of readout resonators. Each readout resonator of a first readout resonator group is arranged to electromagnetically couple to a respective qubit of a first qubit group. Each readout resonator of a second readout resonator group is arranged to electromagnetically couple to a respective qubit of a second qubit group. A resonance frequency of each readout resonator of the first readout resonator group is within a first resonance frequency band, and a resonance frequency of each readout resonator of the second readout resonator group is within a second resonance frequency band that is different from the first resonance frequency band.

Abstract: Josephson junctions (JJ) may replace primary inductance of transformers to realize galvanic coupling between qubits, advantageously reducing size. A long-range symmetric coupler may include a compound JJ (CJJ) positioned at least approximately at a half-way point along the coupler to advantageously provide a higher energy of a first excited state than that of an asymmetric long-range coupler. Quantum processors may include qubits and couplers with a non-stoquastic Hamiltonian to enhance multi-qubit tunneling during annealing. Qubits may include additional shunt capacitances, e.g., to increase overall quality of a total capacitance and improve quantum coherence. A sign and/or magnitude of an effective tunneling amplitude ?eff of a qubit characterized by a double-well potential energy may advantageously be tuned. Sign-tunable electrostatic coupling of qubits may be implemented, e.g., via resonators, and LC-circuits. YY couplings may be incorporated into a quantum anneaier (e.g., quantum processor).

Abstract: According to one embodiment, a coupler includes first to fourth capacitors, first and second inductors, and a first Josephson junction. The first capacitor includes a first capacitor end portion and a first capacitor other-end portion. The first inductor includes a first inductor end portion, and a first inductor other-end portion. The second inductor includes a second inductor end portion, and a second inductor other-end portion. The first Josephson junction includes a first Josephson junction end portion, and a first Josephson junction other-end portion. A space is surrounded with the first inductor, the second inductor, and the first Josephson junction. The third capacitor includes a third capacitor end portion, and a third capacitor other-end portion. The fourth capacitor includes a fourth capacitor end portion, and a fourth capacitor other-end portion.

Abstract: One example describes a superconducting current source system comprising a linear flux-shuttle. The linear flux-shuttle includes an input and a plurality of Josephson transmission line (JTL) stages. Each of the JTL stages includes at least one Josephson junction, an output inductor, and a clock input. The linear flux-shuttle can be configured to generate a direct current (DC) output current via the output inductor associated with each of the JTL stages in response to the at least one Josephson junction triggering in a sequence in each of the JTL stages along the linear flux-shuttle in response to receiving an input pulse at the input and in response to a clock signal provided to the clock input in each of the JTL stages.

Abstract: It is an objective to provide an arrangement for reducing qubit leakage errors in a quantum computing system. According to an embodiment, an arrangement for reducing qubit leakage errors includes a first qubit and a second qubit selectively couplable to each other. The arrangement also includes an energy dissipation structure that is selectively couplable to the first qubit. The energy dissipation structure is configured to dissipate energy transferred from the first qubit. The arrangement further includes a control unit configured to perform a first quantum operation to transfer a property of a quantum state from the first qubit to the second qubit, couple the first qubit to the energy dissipation structure for a time interval, and perform a second quantum operation to transfer the property of the quantum state from the second qubit to the first qubit after the time interval.

Abstract: A capacitively-driven tunable coupler includes a coupling capacitor connecting an open end of a quantum object (i.e., an end of the object that cannot have a DC path to a low-voltage rail, such as a ground node, without breaking the functionality of the object) to an RF SQUID having a Josephson element capable of providing variable inductance and therefore variable coupling to another quantum object.

Abstract: A tunable resonator is formed by shunting a set of asymmetric DC-SQUIDs with a capacitive device. An asymmetric DC-SQUID includes a first Josephson junction and a second Josephson junction, where the critical currents of the first and second Josephson junctions are different. A coupling is formed between the tunable resonator and a qubit such that the capacitively-shunted asymmetric DC-SQUIDs can dispersively read a quantum state of the qubit. An external magnetic flux is set to a first value and applied to the tunable resonator. A first value of the external magnetic flux causes the tunable resonator to tune to a first frequency within a first frequency difference from a resonance frequency of the qubit, the tunable resonator tuning to the first frequency causes active reset of the qubit.

Abstract: A single flux quantum (SFQ) circuit includes a radio frequency (RF) to direct current (DC) conversion stage. A DC to RF current conversion stage is coupled to a single output of the RF to DC conversion stage. The DC to RF current conversion stage includes a plurality of series stacked Josephson Junctions (JJs) having n stages, configured to convert a DC current received from the RF to DC conversion stage and reconvert the DC current to an RF tone.

Abstract: Trap circuits for use with superconducting integrated circuits having capacitively-coupled resonant clock networks are described. An example superconducting integrated circuit (IC) includes a clock structure coupled: (1) to a first Josephson junction (JJ) via a first capacitor, where the first capacitor is configured to receive a clock signal via the clock structure and couple a first bias current to the first JJ, and (2) to a second JJ via a second capacitor, where the second capacitor is configured to receive a clock signal via the clock structure and couple a second bias current to the second JJ. The superconducting IC further includes a trap circuit coupled between the first capacitor and the first JJ, where the trap circuit is configured to attenuate any signals generated by a triggering of the first JJ to reduce crosstalk between the first JJ and the second JJ.

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: There is described a microwave device and methods of operating same. The device comprises at least one superconducting qubit coupled to a transmission line defining a first port, and a filter. The filter comprises a first resonant element having a first resonance frequency f1, positioned along the transmission line between the first port and the qubit, and a second resonant element having a second resonance frequency f2 different from f1 and positioned along the transmission line between the first resonant element and the qubit.

Abstract: 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.

Abstract: A CNOT gate includes a clock line, splitter, and first and second store-and-launch gates (SNLs) to each output a fluxon in accordance with a clock fluxon and polarities of an input fluxon and the clock fluxon. The CNOT gate also includes first and second IDSN gates. When one fluxon input is received, the IDSN gate outputs one fluxon in accordance with a polarity of the fluxon input. When two fluxon inputs are received, the IDSN gate outputs two fluxons in accordance with an inverse polarity of the fluxon inputs. The CNOT gate also includes first and second NOT gates to receive a fluxon output from the first IDSN gate and output a fluxon of opposite polarity, and a third NOT gate to receive a fluxon output from the second IDSN gate and output a fluxon of opposite polarity.

Abstract: A qubit includes a superconducting loop interrupted by a plurality of magnetic flux tunneling elements, such as DC SQUIDs, leaving superconducting islands between the elements. An effective transverse magnetic moment is formed by magnetically tuning each element to yield a large tunneling amplitude. The electrical polarization charge on an island is tuned to produce destructive interference between the tunneling amplitudes using the Aharonov-Casher effect, resulting in an effectively zero transverse field. Biasing the charge away from this tuning allows tunneling to resume with a large amplitude. Interrupting the island with a third tunneling path, such as a Josephson junction, permits independently tuning and biasing the two islands that result, enabling effective control of two independent (X and Y) transverse fields.

Abstract: First and second superconductive sensors receive an electromagnetic signal. The first and second superconductive sensors are spaced apart such that there is a phase difference between the electromagnetic signal as received at the first and second superconductive sensors. The first and second superconductive sensors output respective first and second voltage signals corresponding to the electromagnetic signal as received by the first and second superconductive sensors. A nonlinear detector detects a voltage difference between the first and second voltage signals and provides an output signal representing the detected voltage difference. The output signal corresponds to the phase difference between the electromagnetic signal as received at the first and second superconductive sensors.

Abstract: The embodiments herein describe technologies of an amplifier circuit that is designed for wideband communication with superconductive components in cryogenic applications, including Josephson Junction integrated circuits, operating in a cryogenic temperature domain (e.g., 4K). The amplifier circuit operates in a temperature domain (e.g., 77K) that is higher than the cryogenic temperature domain of the superconductive components.

Abstract: A tunable resonator is formed by shunting a set of asymmetric DC-SQUIDs with a capacitive device. An asymmetric DC-SQUID includes a first Josephson junction and a second Josephson junction, where the critical currents of the first and second Josephson junctions are different. A coupling is formed between the tunable resonator and a qubit such that the capacitively-shunted asymmetric DC-SQUIDs can dispersively read a quantum state of the qubit. An external magnetic flux is set to a first value and applied to the tunable resonator. A first value of the external magnetic flux causes the tunable resonator to tune to a first frequency within a first frequency difference from a resonance frequency of the qubit, the tunable resonator tuning to the first frequency causes active reset of the qubit.

Abstract: One example includes a superconducting transmission driver system. The system includes a latching gate stage comprising at least one Josephson junction configured to switch from an off state to an oscillating voltage state to provide an oscillating voltage at a control node in response to a single flux quantum (SFQ) pulse received at an input. The system further includes a low-pass filter stage coupled to the control node and configured to convert the oscillating voltage to a pulse signal to be transmitted over a transmission line.

Abstract: A technique relates to qubit drive and readout. A first lossless microwave switch is connected to a quantum system. A second lossless microwave switch is connectable to the first lossless microwave switch. A quantum-limited amplifier is connectable to the second lossless microwave switch.

Abstract: A technique relates to operating a multimode Josephson parametric converter as a multimode quantum limited amplifier. The multimode Josephson parametric converter receives multiple quantum signals in parallel at different resonance frequencies. The multimode Josephson parametric converter amplifies simultaneously the multiple quantum signals, according to pump signals applied to the multimode Josephson parametric converter. The multiple quantum signals having been amplified at the different resonance frequencies are reflected, according to the pump signals.

Abstract: A technique relates to operating a multimode josephson parametric converter as a multimode quantum limited amplifier. The multimode. Josephson parametric converter receives multiple quantum signals in parallel at different resonance frequencies. The multimode Josephson parametric converter amplifies simultaneously the multiple quantum signals, according to pump signals applied to the multimode Josephson parametric converter. The multiple quantum signals having been amplified at the different resonance frequencies are reflected, according to the pump signals.

Abstract: A mechanism relates a superconductor circuit. A ? circuit includes a first node connecting a Purcell capacitor to a qubit coupling capacitor, a second node connecting the Purcell capacitor to a readout coupling capacitor, and a third node connecting the qubit coupling capacitor to the readout coupling capacitor. A qubit is connected to the first node and has a qubit frequency. A readout resonator connects to the third node combining with the Purcell capacitor to form a filter. Capacitance of the Purcell capacitor is determined as a factor of the qubit frequency of the qubit and blocks emissions of the qubit at the qubit frequency. Capacitance of the Purcell capacitor causes destructive interference, between a first path containing Purcell capacitor and a second path containing both the qubit coupling capacitor and readout coupling capacitor, in order to block emissions of the qubit at the qubit frequency to the external environment.

Abstract: A circuit includes a magnetic logic unit including input terminals, output terminals, a field line, and magnetic tunnel junctions (MTJs). The field line electrically connects a first and a second input terminal, and is configured to generate a magnetic field based on an input to at least one of the first and the second input terminal. The input is based on a first analog input to the circuit. Each MTJ is electrically connected to a first and a second output terminal, and is configured such that an output of at least one of the first and the second output terminal varies in response to a combined resistance of the MTJs. The resistance of the MTJs varies based on the magnetic field. The circuit is configured to mix the first analog input and a second analog input to generate an analog output based on the output of the second output terminal.

Abstract: One embodiment describes a Josephson current source system. The system includes a flux-shuttle loop comprising a plurality of stages arranged in a series loop. Each of the plurality of stages includes at least one Josephson junction. The flux-shuttle loop can be configured, when activated, to sequentially trigger the at least one Josephson junction in each of the plurality of stages about the flux-shuttle loop in response to an inductively-coupled AC clock signal to generate a DC output current provided through an output inductor. The system also includes a flux injector system that is configured to activate the flux-shuttle loop. The flux injector system is further configured to automatically deactivate the flux-shuttle loop in response to an amplitude of the DC output current increasing to a predetermined deactivation threshold.

Abstract: A quantum information processing system includes a waveguide having an aperture, a non-linear quantum circuit disposed in the waveguide and an electromagnetic control signal source coupled to the aperture.

Abstract: A quantum information processing system includes a waveguide having an aperture, a non-linear quantum circuit disposed in the waveguide and an electromagnetic control signal source coupled to the aperture.

Abstract: Methods and apparatuses are provided for controlling the state of a qubit. A qubit apparatus includes a qubit and a load coupled to the qubit through a filter. The filter has at least a first pass band and a first stop band. A qubit control is configured to tune the qubit to alter an associated transition frequency of the qubit from a first frequency in the first stop band of the filter to a second frequency in the first pass band of the filter.

Abstract: Systems and methods for reading out the states of superconducting flux qubits may couple magnetic flux representative of a qubit state to a DC-SQUID in a variable transformer circuit. The DC-SQUID is electrically coupled in parallel with a primary inductor such that a time-varying (e.g., AC) drive current is divided between the DC-SQUID and the primary inductor in a ratio that is dependent on the qubit state. The primary inductor is inductively coupled to a secondary inductor to provide a time-varying (e.g., AC) output signal indicative of the qubit state without causing the DC-SQUID to switch into a voltage state. Coupling between the superconducting flux qubit and the DC-SQUID may be mediated by a routing system including a plurality of latching qubits. Multiple superconducting flux qubits may be coupled to the same routing system so that a single variable transformer circuit may be used to measure the states of multiple qubits.

Abstract: Disclosed is an arrangement including a support and a super-conductive film which is arranged thereon. The film has a plurality of holes in order to form a perforated grating. The holes are optionally round holes having increasing sizes, triangular holes, or holes which are arranged in a meandering manner in the film, and which produce improved properties in relation to signal conversion by a vortex diode and/or in a filter. A DC signal is directly removed therein without additional electronics.

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: A quantum information processing system includes a waveguide having an aperture, a non-linear quantum circuit disposed in the waveguide and an electromagnetic control signal source coupled to the aperture.

Abstract: Methods and apparatuses are provided for storing a quantum bit. One apparatus includes a first phase qubit, a second phase qubit, and a common bias circuit configured to provide a first bias to the first phase qubit and a second bias to the second phase qubit, such that noise within the first bias is anti-correlated to noise within the second bias.

Abstract: One embodiment of the invention includes a quantum processor system. The quantum processor system includes a first resonator having a first characteristic frequency and a second resonator having a second characteristic frequency greater than the first characteristic frequency. A qubit cell is coupled to each of the first resonator and the second resonator. The qubit cell has a frequency tunable over a range of frequencies including the first characteristic frequency and the second characteristic frequency. A classical control mechanism is configured to tune the frequency of the qubit cell as to transfer quantum information between the first resonator and the second resonator.