Abstract: A system and method comprising a cryogenic adiabatic circuit in a cryogenic environment and a clock generator at a higher temperature, the circuit's clock lines can be connected across the temperature gradient to the clock generator, where the clock generator runs below the frequency that would yield power dissipation equal to the static dissipation of a functionally equivalent CMOS circuit at room temperature, resulting in lower power for the function than possible at room temperature irrespective of the speed of operation.

Abstract: A quantum processing apparatus comprises control electronics, a switching unit, a bias line, and N electronic circuits. Both the switching unit and the bias line are connected to the control electronics. The N circuits comprise N respective, non-volatilely tunable resistors and N respective frequency-tunable, solid-state qubits. The control electronics are configured to individually tune the resistors via the switching unit, in a configuration mode of the apparatus; and apply a voltage bias to the electronic circuits via the bias line, in an operation mode of the apparatus. The electronic circuits are configured to passively apply respective bias signals to the qubits, wherein such bias signals are impacted by the resistors, in response to the voltage bias applied via the bias line, to operate the qubits at respective frequencies determined according to the respective bias signals.

Abstract: According to some aspects, a quantum information system is provided that includes an ancilla qubit; a qudit coupled to the ancilla qubit, a detector configured to generate a detection result based on a quantum state of the ancilla qubit, and a driving source coupled to the qudit and the ancilla qubit and configured to apply at least one qudit driving signal to the qudit based on the detection result and at least one qubit driving signal to the qudit based on the detection result.

Abstract: A reciprocal quantum logic (RQL) phase-mode flip-flop includes a storage loop and a comparator, each of which includes Josephson junctions (JJs). A data input, provided as a positive or negative single flux quantum (SFQ) pulse, is stored in the storage loop to set the storage loop in a positive or negative state, respectively, effectively biasing an output JJ shared between the storage loop and a comparator. The data input is captured to the output upon the receipt of a logical clock SFQ reciprocal pulse pair to the comparator, when one of the pulses in the pair causes the output JJ to preferentially trigger over an escape junction in the comparator, owing to the output JJ having been biased by current in the storage loop.

Abstract: A system and method for controlling superconducting qubits is provided. In some aspects the method includes assembling, using a controller of a quantum computing system, a pulse subsequence that comprises pairs of voltage pulses timed symmetrically with respect to a period corresponding to a qubit frequency of a superconducting qubit in the quantum computing system. The method also includes generating, using the controller, a pulse sequence using a repetition of a pulse subsequence. The method further includes controlling the superconducting qubit by applying the pulse sequence to the superconducting qubit using a single flux quantum (“SFQ”) driver coupled thereto.

Abstract: Non-destructive read out (NDRO) circuits are provided for use in reciprocal quantum logic (RQL) superconducting systems. Each NDRO circuit includes a “body” circuit that provides a single or multi-state sub-critical bias current to one or many independent “tail” circuitries. Each “tail” has minimal effect on the “body” thereby preventing any interference or destruction to the state of the “body” circuitry. The circuits reduce device count and thereby increase circuit density, simplify and reduce the cost of fabrication, and provide functionality not available in existing designs, such as the ability to write a state and read it in the same operation cycle. The NDRO circuits provide more compact unit cells useful in memory or logic arrays, demanding fewer resources with increased functionality. The circuits also provide compact cells for AND, AND-OR, A-NOT-B, inverter, multiplexer, and demultiplexer gates.

Abstract: Structures and techniques, using superconducting Josephson-junction based circuits, to directly engineer physical multiqubit (or “many-qubit”) interactions in a non-perturbative manner. In one embodiment, a system for multiqubit interaction includes: a multispin coupler including a plurality of loops, each loop having a pair of Josephson junctions; and a plurality of qubits each inductively coupled to the multispin coupler.

Abstract: A Josephson inverter gate circuit provides efficient implementation of polarity or logical inversion while eliminating the need for physically large high-efficiency magnetic transformers in the signal path. The circuit can consist of a half-twisted Josephson transmission line (JTL) or a JTL with an unshunted floating Josephson junction that produces two single flux quantum (SFQ) pulses when triggered by an SFQ input signal, which results in an output SFQ signal of reversed polarity. Implemented as a logical inverter, proper initialization of the circuit is accomplished within the signal inversion stage with flux biasing.

Abstract: Large fan-in logical gate circuits for use in reciprocal quantum logic (RQL) systems and related methods permit for improved efficiency and density of RQL logic. A majority 3-of-5 gate circuit, as described, can be extended to include more than five inputs, and can also be modified to create AND gates, OR gates, and OA gates. The gate circuits can accommodate inputs and provide outputs each in the form of single flux quantum (SFQ) pulses, either positive or negative, to indicate asserted and de-asserted logic states, respectively.

Abstract: An inverting reciprocal quantum logic (RQL) gate circuit has an input stage having a logical input asserted based on receiving a positive single flux quantum (SFQ) pulse and an output stage comprising phase mode logic (PML) inverter circuitry. The input stage includes one or more storage loops, at least one being associated with each logical input, each comprising an input Josephson junction (JJ), a storage inductor, and a logical decision JJ, the logical decision JJ being common to all the storage loops associated with the logical inputs and being configured to trigger based on biasing provided by one or more currents stored in the storage loops and a first bias signal provided to the input stage. The output stage de-asserts an output and is provided with a second bias signal having a second state opposite of a first state of the first bias signal.

Abstract: A Josephson inverter gate circuit provides efficient implementation of polarity or logical inversion while eliminating the need for physically large high-efficiency magnetic transformers in the signal path. The circuit can consist of a half-twisted Josephson transmission line (JTL) or a JTL with an unshunted floating Josephson junction that produces two single flux quantum (SFQ) pulses when triggered by an SFQ input signal, which results in an output SFQ signal of reversed polarity. Implemented as a logical inverter, proper initialization of the circuit is accomplished within the signal inversion stage with flux biasing.

Abstract: A reversible superconducting circuit includes a plurality of Josephson transmission lines. A first line is configured to transmit a control fluxon when a first input is active. A second line is configured to transmit a target fluxon to one of a third and a fourth line. The circuit is configured to transmit the fluxons at substantially the same time. The second line is configured to transmit the target fluxon to the third line, due to an interaction between the control fluxon and the target fluxon, only if the control fluxon is transmitted at substantially the same time as the target fluxon. The second line is configured to transmit the target fluxon to the fourth line, due to following an adiabatic trajectory, only if no control fluxon is transmitted at substantially the same time as the target fluxon.

Abstract: This circuit (100) includes: an intermediate layer (103), made from a conductive material and configured according to a pattern; a first electrode and a plurality of electrodes, which includes at least second and third electrodes (126, 127, 128), each electrode including: A polarizer, made from a ferromagnetic material, placed at a particular point of the pattern of the intermediate layer, and having a magnetization; A superconducting layer, made of a superconducting material, arranged on the polarizer; and a control means (112) able to modify the magnetization of the polarizer of the second electrode; another control means (122) able to modify the magnetization of the polarizer of the third electrode; bias terminals for applying a bias signal; and, terminals for measuring an output signal, a level of the output signal being correlated with a mutual orientation of the first, second and third magnetizations.

Abstract: A device including an array of superconducting logic cells, where each of the superconducting logic cells is configured to receive at least one input and provide at least one output, is provided. Each of the superconducting logic cells includes at least one Josephson junction, whose state changes based on at least a biasing condition caused by a phase of a first clock or a phase of a second clock. The array of the superconducting logic cells is configured to perform at least one operation based at least on a connection arrangement of the array of the superconducting logic cells.

Abstract: Increasing the energy scale of a quantum processor improves its performance. Energy scale of a quantum processor may be increased by increasing the coupling strength of communicatively coupled superconducting devices comprised in the quantum processor. Configuring the physical dimensions of communicatively coupled superconducting devices such that an intentional direct coupling is induced between a pair of superconducting devices communicatively coupled by a coupling device may controllably add an additional mutual inductance to the mutual inductance of the pair of superconducting devices. Furthermore, reducing the beta parameter of a coupling device may improve the tunability of the coupling device. The combined effects of improved tunability of the coupling devices and the increased coupling strength between superconducting devices communicatively coupled by respective coupling devices comprised in the quantum processor may thus improve the performance of the quantum processor.

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 computer system employs a network that between a data programming system and one or more superconducting programmable devices of a superconducting processor chip. Routers on the network, such as first-, second- and third-stage routers direct communications with the superconducting programmable devices. A superconducting memory register may load data signals received from a first-stage router into corresponding superconducting programmable devices. The system may employ additional superconducting chips, first-, second- or third-stage routers.

Abstract: A device includes a volume bounded by electromagnetically conducting walls, an aperture in a bounding wall of the electromagnetically conducting walls, a plurality of quantum systems disposed within the volume and an electromagnetic field source coupled to the volume via the aperture.

Abstract: Superconducting single flux quantum circuits are disclosed herein, each having at least one Josephson junction which will flip when the current through it exceeds a critical current. Bias current for the Josephson junction is provided by a biasing transformer instead of a resistor. The lack of any bias resistors ensures that unwanted power dissipation is eliminated.

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 superconducting readout system includes a computation qubit; a measurement device to measure a state of the computation qubit; and a latch qubit that mediates communicative coupling between the computation qubit and the measurement device. The latch qubit includes a qubit loop that includes at least two superconducting inductors coupled in series with each other; a compound Josephson junction that interrupts the qubit loop that includes at least two Josephson junctions coupled in series with each other in the compound Josephson junction and coupled in parallel with each other with respect to the qubit loop; and a first clock signal input structure to couple clock signals to the compound Josephson junction.

Abstract: In one embodiment, the disclosure relates to a method and apparatus for controlling the energy state of a qubit by bringing the qubit into and out of resonance by coupling the qubit to a flux quantum logic gate. The qubit can be in resonance with a pump signal, with another qubit or with some quantum logic gate. In another embodiment, the disclosure relates to a method for controlling a qubit with RSFQ logic or through the interface between RSFQ and the qubit.

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: Superconducting single flux quantum circuits are disclosed herein, each having at least one Josephson junction which will flip when the current through it exceeds a critical current. Bias current for the Josephson junction is provided by a biasing transformer instead of a resistor. The lack of any bias resistors ensures that unwanted power dissipation is eliminated.

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: Superconducting single flux quantum circuits are disclosed herein, each having at least one Josephson junction which will flip when the current through it exceeds a critical current. Bias current for the Josephson junction is provided by a biasing transformer instead of a resistor. The lack of any bias resistors ensures that unwanted power dissipation is eliminated.

Abstract: A system for communicably coupling between two superconducting qubits may include an rf-SQUID coupler having a loop of superconducting material interrupted by a compound Josephson junction and a first magnetic flux inductor configured to controllably couple to the compound Josephson junction. The loop of superconducting material may be positioned with respect to a first qubit and a second qubit to provide respective mutual inductance coupling therebetween. The coupling system may be configured to provide ferromagnetic coupling, anti-ferromagnetic coupling, and/or zero coupling between the first and second qubits. The rf-SQUID coupler may be configured such that there is about zero persistent current circulating in the loop of superconducting material during operation.

Abstract: In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.

Abstract: In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.

Abstract: Supercooled electronics often use Rapid Single Flux Quantum (RSFQ) digital circuits. The output voltages from RSFQ devices are too low to be directly interfaced with semiconductor electronics, even if the semiconductor electronics are cooled. Techniques for directly interfacing RSFQ digital circuits with semiconductor electronics are disclosed using a novel inverting transimpedance digital amplifier in conjunction with a non-inverting transimpedance digital amplifier to create a differential transimpedance digital amplifier that permits direct interfacing between RSFQ and semiconductor electronics.

Abstract: In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.

Abstract: In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.

Abstract: In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.

Abstract: The disclosure relates to a method for providing a logic circuit element. The method includes arranging a series of Josephson junctions between a first Josephson junction and a second Josephson junction, the first Josephson junction having a first critical current (Ic1) and the second Josephson junction having a second critical current (Ic2); providing a working current to the first Josephson junction, the working current transmitting to the second Josephson junction through the series of the Josephson junctions; wherein the working current is sufficiently high to trigger the second Josephson junction while sufficiently low to not disturb super-conductivity of the series of intermediate Josephson junctions.

Abstract: Superconducting single flux quantum circuits are disclosed herein, each having at least one Josephson junction which will flip when the current through it exceeds a critical current. Bias current for the Josephson junction is provided by a biasing transformer instead of a resistor. The lack of any bias resistors ensures that unwanted power dissipation is eliminated.

Abstract: In one embodiment, the disclosure relates to a single flux quantum (SFQ) signal transmission line powered by an AC power source. The AC power source supplies power to a transformer having a primary winding and a secondary winding. The primary winding receives the AC signal and the secondary winding communicates the signal to the SFQ transmission line. The transmission line can optionally include an input filter circuit for receiving the incoming SFQ pulse. The filter circuit can have a resistor and an inductor connected in parallel. In an alternative arrangement, the filter circuit can comprise of an inductor. A first Josephson junction can be connected to the filter circuit and to the secondary winding. The Josephson junction triggers in response to the incoming SFQ pulse and regenerates a pulse signal in response to a power discharge from the secondary winding.

Abstract: Reversible and self reversing multi-value scrambling functions created by applying multi-value inverters are disclosed. The generation of possible multi-value inverters is also presented. Corresponding multi-value descrambling functions are also disclosed. The multi-value functions are used in circuits that scramble and descramble multi-value signals. The multi-value functions can also be used in signal generators. Such signal generators do not require the use of multipliers. The auto-correlation of the signals generated by the signal generators is also presented. Electronic circuits that implement the multi-value functions are also described.

Abstract: The disclosure relates to a method for providing a logic circuit element. The method includes arranging a series of Josephson junctions between a first Josephson junction and a second Josephson junction, the first Josephson junction having a first critical current (Ic1) and the second Josephson junction having a second critical current (Ic2); providing a working current to the first Josephson junction, the working current transmitting to the second Josephson junction through the series of the Josephson junctions; wherein the working current is sufficiently high to trigger the second Josephson junction while sufficiently low to not disturb super-conductivity of the series of intermediate Josephson junctions.

Abstract: A programmable phase shifter is constructed of Rapid Single Flux Quantum (RSFQ) logic elements. The logic elements may include an RSFQ inverter and an RSFQ T flip-flop. A digital word comprising N bits is used to control the amount of phase shift and the phase shifter selectively imparts a respective phase shift for any of 2N states that can be represented by the digital word. The RSFQ logic elements utilize Josephson junctions which operate in the superconducting temperature domain.

Abstract: Supercooled electronics often use Rapid Single Flux Quantum (RSFQ) digital circuits. The output voltages from RSFQ devices are too low to be directly interfaced with semiconductor electronics, even if the semiconductor electronics are cooled. Techniques for directly interfacing RSFQ digital circuits with semiconductor electronics are disclosed using a novel inverting transimpedance digital amplifier in conjunction with a non-inverting transimpedance digital amplifier to create a differential transimpedance digital amplifier that permits direct interfacing between RSFQ and semiconductor electronics.

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: Superconducting single flux quantum circuits are disclosed herein, each having at least one Josephson junction which will flip when the current through it exceeds a critical current. Bias current for the Josephson junction is provided by a biasing transformer instead of a resistor. The lack of any bias resistors ensures that unwanted power dissipation is eliminated.

Abstract: Objects of the present invention are to provide an integration circuit which produces no integration leak so that the bit accuracy is improved in a sigma-delta modulation circuit or a delta modulator circuit, which is based on a single flux quantum circuit that uses a flux quantum as an information carrier, and to provide a method for reducing thermal noise and quantization noise. According to the present invention, an integration circuit is formed by Josephson junctions and an inductor to reduce the integration leak, and a plurality of modulator circuits are connected to one another so as to add up each output. As a result, it is possible to reduce the influence of thermal noise exerted upon the bit accuracy, the thermal noise having no correlativity to one another.

Abstract: Apparatus, articles and methods relate to anti-symmetric superconducting devices for coupling superconducting qubits.

Abstract: A superconducting circuit includes a first transformer to produce a first alternating-current output at a secondary-side inductor, a second transformer to produce a second alternating-current output at a secondary-side inductor, a first pulse generating circuit to produce a single flux quantum pulse responsive to the first alternating-current output, a second pulse generating circuit to produce a single flux quantum pulse responsive to the second alternating-current output, and a confluence buffer circuit to merge the single flux quantum pulses from the pulse generating circuits, wherein each of the pulse generating circuits includes a superconducting loop including the secondary-side inductor, a first Josephson junction situated in the superconducting loop to generate the single flux quantum pulse, and a second Josephson junction situated in the superconducting loop, a threshold value of the second Josephson junction for an electric current flowing through the secondary-side inductor being different from tha

Abstract: A single flux quantum (SFQ) pulse is generated (502) by injecting a superconductor output signal as a first signal at a “start” input (108) coupled to a superconductor delay element (104). The SFQ pulse is reflected (504) back and forth between first and second superconductor reflectors (102, 106) coupled to opposite ends of the superconductor delay element, thereby generating a time-disperse plurality of SFQ pulses at an output (110) coupled to the superconductor delay element. Thereafter, a second signal is input at a “stop” input (112) coupled to one of the first and second superconductor reflectors, thereby interrupting (506) the reflecting of the SFQ pulse at the one of the first and second superconductor reflectors, thus ending the generating of the time-disperse plurality of SFQ pulses at the output.

Abstract: In one embodiment, a two-junction phase qubit includes a superconducting loop and two Josephson junctions separated by a mesoscopic island on one side and a bulk loop on another side. The material forming the superconducting loop is a superconducting material with an order parameter that violates time reversal symmetry. In one embodiment, a two-junction phase qubit includes a loop of superconducting material, the loop having a bulk portion and a mesoscopic island portion. The loop further includes a relatively small gap located in the bulk portion. The loop further includes a first Josephson junction and a second Josephson junction separating the bulk portion from the mesoscopic island portion. The superconducting material on at least one side of the first and second Josephson junctions has an order parameter having a non-zero angular momentum in its pairing symmetry. In one embodiment, a qubit includes a superconducting loop having a bulk loop portion and a mesoscopic island portion.

Abstract: A rapid single-flux-quantum RSFQ logic circuit includes a first circuit portion having a first end grounded and having in-series connected first and second Josephson junctions. A second circuit portion has a first end grounded and has in-series connected third and fourth Josephson junctions. A first inductance element connects a second end of the first circuit portion to a second end of the second circuit portion. A tap is provided in the first inductance element, an input current signal being supplied to the tap. A bias current source is connected to a first connection node between the first and second Josephson junctions. A second inductance element connects the first connection node to a second connection node between the third and fourth Josephson junctions. A superconducting quantum interference device has fifth and sixth Josephson junctions and is coupled to the second inductance element through a magnetic field.

Abstract: A high gain clock circuit that includes an input section that receives an input clock on an input section input. A self terminating pre-charge section is connected to the input section and includes domino logic. An output section is connected to the self terminating pre-charge section and produces an output clock at an output section output. The clock circuit encompasses a small area and achieves high gain at the output section output relative to the input section input. The high gain clock circuit has higher gain than known circuits and is characterized by fast rise time and slower fall time.

Abstract: The invention provides a universal, delay-insensitive RSFQ logic cell comprising two input circuits and two clock circuits, each containing a plurality of Josephson elements. The two input circuits generate and sustain persistent currents in response to input currents. The first clock circuit is arranged to be in electrical contact with the first input circuit such that a portion of the SFQ persistent current from the input circuit combines with an SFQ pulse, generated in the clock circuit, to trigger the generation of a SFQ output pulse. The second clock circuit and the second input circuit are connected in a similar manner. The first input circuit is arranged to be in electrical contact with the second input circuit so that a portion of their SFQ currents combine and trigger the generation of a SFQ output pulse. The universal logic cell can be configured to perform various digital/logical functions.