According to an example aspect of the present invention, there is provided a travelling wave parametric amplifier comprising a waveguide transmission line comprising therein at least ten Josephson elements, wherein each of the at least ten Josephson element comprises a loop, with exactly one Josephson junction of first size on one half of the loop and at least two Josephson junctions of a second size on a second half of the loop, the second size being larger than the first size, a flux bias line configured to generate a magnetic flux threading each of the at least one loop, and a set of resistors coupled with the flux bias line.

According to an example aspect of the present invention, there is provided a travelling wave parametric amplifier comprising a waveguide transmission line comprising therein at least ten Josephson elements, wherein each of the at least ten Josephson element comprises a loop, with exactly one Josephson junction of first size on one half of the loop and at least two Josephson junctions of a second size on a second half of the loop, the second size being larger than the first size, a flux bias line configured to generate a magnetic flux threading each of the at least one loop, and a set of resistors coupled with the flux bias line.

A primary single photon optoelectronic neuron includes a photonic synaptic input waveguide; an optoelectronic synapse; a synapto-dendritic electrical connection in communication with the optoelectronic synapse; an electronic dendrite in communication with the synapto-dendritic electrical connection; a dendrite-neuronal electrical interface in communication with the electronic dendrite; an integrator in communication with the dendrite-neuronal electrical interface; a superconducting wire in communication with the integrator; an axon hillock electronic-to-photonic transducer in communication with the superconducting wire; and an axonic waveguide in communication with the axon hillock electronic-to-photonic transducer and that receives the axonic photonic signal. Producing an axonic photonic signal by a primary single photon optoelectronic neuron includes producing an optoelectronic synapse electronic output signal; producing an electronic dendrite electrical output signal from the optoelectronic synapse electronic output signal; producing an axonic electrical signal from the optoelectronic synapse electronic output signal; and producing the axonic photonic signal from the axonic electrical signal.

A primary single photon optoelectronic neuron includes a photonic synaptic input waveguide; an optoelectronic synapse; a synapto-dendritic electrical connection in communication with the optoelectronic synapse; an electronic dendrite in communication with the synapto-dendritic electrical connection; a dendrite-neuronal electrical interface in communication with the electronic dendrite; an integrator in communication with the dendrite-neuronal electrical interface; a superconducting wire in communication with the integrator; an axon hillock electronic-to-photonic transducer in communication with the superconducting wire; and an axonic waveguide in communication with the axon hillock electronic-to-photonic transducer and that receives the axonic photonic signal. Producing an axonic photonic signal by a primary single photon optoelectronic neuron includes producing an optoelectronic synapse electronic output signal; producing an electronic dendrite electrical output signal from the optoelectronic synapse electronic output signal; producing an axonic electrical signal from the optoelectronic synapse electronic output signal; and producing the axonic photonic signal from the axonic electrical signal.

A wireless Josephson-junction-based amplifier is described that provides improved tunability and increased control over both a quality factor Q and participation ratio p of the amplifier. The device may be fabricated on a chip and mounted in a waveguide. No wire bonding between the amplifier and coaxial cables or a printed circuit board is needed. At least one antenna on the chip may be used to couple energy between the waveguide and wireless JBA. The amplifier is capable of gains greater than 25 dB.

A wireless Josephson-junction-based amplifier is described that provides improved tunability and increased control over both a quality factor Q and participation ratio p of the amplifier. The device may be fabricated on a chip and mounted in a waveguide. No wire bonding between the amplifier and coaxial cables or a printed circuit board is needed. At least one antenna on the chip may be used to couple energy between the waveguide and wireless JBA. The amplifier is capable of gains greater than 25 dB.

A radio-frequency (RF) to direct current (DC) converter is provided. When a DC electrical current is applied via a DC input port of the converter, the DC electrical current is shunted to ground through a Josephson junction (JJ) of the converter and substantially no DC electrical current flows through a resistor of the converter, and when an RF electrical current is applied via an RF input port of the converter, output trains of SFQ current pulses from a DC to SFQ converter of the RF-to-DC converter with pulse-to-pulse spacing inversely proportional to the RF electrical current frequency cause the JJ to switch at a rate commensurate with an RF frequency of the RF electrical current to generate a steady state voltage across the JJ linearly dependent on the RF frequency.

A radio-frequency (RF) to direct current (DC) converter is provided. When a DC electrical current is applied via a DC input port of the converter, the DC electrical current is shunted to ground through a Josephson junction (JJ) of the converter and substantially no DC electrical current flows through a resistor of the converter, and when an RF electrical current is applied via an RF input port of the converter, output trains of SFQ current pulses from a DC to SFQ converter of the RF-to-DC converter with pulse-to-pulse spacing inversely proportional to the RF electrical current frequency cause the JJ to switch at a rate commensurate with an RF frequency of the RF electrical current to generate a steady state voltage across the JJ linearly dependent on the RF frequency.

A thermal and environmental noise suppressing interface circuit which is configured to operate cold and is configured to perform biasing with suppression of noise currents from room temperature noise voltages and dc coupled rf readout of a superconducting device under test with a single coaxial cable or equivalent conductor pair. The circuit is configured to suppress the propagation of thermal and environmental noises to/from sensors operating at a different temperature from its operating and control equipment while maintaining a single input-output channel, and provides for the placement of a local grounding impedance on an intercept board.

High-saturation power Josephson ring modulators and fabrication of the same are provided. A Josephson ring modulator can comprise a plurality of matrix junctions. Matrix junctions of the plurality of matrix junctions can comprise respective superconducting parallel branches that can comprise a plurality of Josephson junctions operatively coupled in a series configuration. A method can comprise forming a first matrix junction comprising arranging a first group of Josephson junctions as first parallel branches. The method can also comprise forming a second matrix junction comprising arranging a second group of Josephson junctions as second parallel branches. Further, the method can comprise forming a third matrix junction comprising arranging a third group of Josephson junctions as third parallel branches. In addition, the method can comprise forming a fourth matrix junction comprising arranging a fourth group of Josephson junctions as fourth parallel branches.