A tunable oscillator including a Josephson junction. In some embodiments, the tunable oscillator includes a first superconducting terminal, a second superconducting terminal, a graphene channel including a portion of a graphene sheet, and a conductive gate. The first superconducting terminal, the second superconducting terminal, and the graphene channel together may form a Josephson junction having an oscillation frequency, and the conductive gate may be configured, upon application of a voltage across the conductive gate and the graphene channel, to modify the oscillation frequency.

An oscillation apparatus includes: an oscillator including a resonator and a magnetic-field generating unit, the resonator including a loop circuit and a capacitor, the loop circuit including a first superconducting line, a first Josephson junction, a second superconducting line, and a second Josephson junction connected in a ring shape, the magnetic-field generating unit being configured to apply a magnetic field to the loop circuit, and the oscillator being configured to perform parametric oscillation; a read-out unit for reading out an internal state of the oscillator; and a filter configured to restrict transmission of a signal in a predetermined frequency band. A circuit in which the capacitor and the loop circuit are connected in a ring shape is connected to the read-out unit through the filter.

An oscillation apparatus includes: an oscillator including a resonator and a magnetic-field generation unit, the resonator including a loop circuit and a capacitor, the loop circuit including a first superconducting line, a first Josephson junction, a second superconducting line, and a second Josephson junction connected in a ring shape, the magnetic-field generation unit being configured to apply a magnetic field to the loop circuit, and the oscillator being configured to perform parametric oscillation; a read-out unit for reading out an internal state of the oscillator; and a circuit component in which a coupling strength between the oscillator and the read-out unit is variable. The oscillator is connected to the read-out unit through the circuit component.

A resonator, an oscillator, and a quantum computer in which both moderate nonlinearity and a low loss are achieved, and the area occupied by the circuit can be reduced are provided. A resonator (100) includes at least one loop circuit (110) in which a first superconducting line (101), a first Josephson junction (103), a second superconducting line (102), and a second Josephson junction (104) are connected in a ring shape, at least one third Josephson junction (130) provided separately from the Josephson junction included in the loop circuit (110), and a capacitor (120), in which the loop circuit (110), the third Josephson junction (130), and the capacitor (120) are connected in a ring shape.

A resonator, an oscillator, and a quantum computer in which the area occupied by the circuit can be reduced is provided. A resonator (100) includes a loop circuit (110) in which a first superconducting line (101), a first Josephson junction (103), a second superconducting line (102), and a second Josephson junction (104) are connected in a ring shape, and a capacitor (120). The capacitor (120) and the loop circuit (110) are connected in a ring shape.

A tunable oscillator including a Josephson junction. In some embodiments, the tunable oscillator includes a first superconducting terminal, a second superconducting terminal, a graphene channel including a portion of a graphene sheet, and a conductive gate. The first superconducting terminal, the second superconducting terminal, and the graphene channel together may form a Josephson junction having an oscillation frequency, and the conductive gate may be configured, upon application of a voltage across the conductive gate and the graphene channel, to modify the oscillation frequency.

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.

A resonator, an oscillator, and a quantum computer capable of preventing oscillation conditions for generating a parametric oscillation from becoming complicated are provided. A resonator includes at least one loop circuit in which a first superconducting line, a first Josephson junction, a second superconducting line, and a second Josephson junction are connected in a ring shape, in which critical current values of the first and second Josephson junctions are different from each other.

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.

According to one embodiment, an electronic circuit includes a first conductive component, a second conductive component, a first current path, and a second current path. The second conductive component is capacitively coupled to the first conductive component. The first current path of a superconductor includes a first portion and a second portion. The first portion is connected to the first conductive component. The second portion is connected to the second conductive component. The first current path includes N first Josephson junctions connected in series and provided between the first and second portions. The second current path of a superconductor includes a third portion and a fourth portion. The third portion is connected to the first conductive component. The fourth portion is connected to the second conductive component. The second current path includes a second Josephson junction connected in series and provided between the third and fourth portions.