In a general aspect, parametric amplification is performed in a quantum computing system. In some cases, a traveling wave parametric amplifier (TWPA) includes a plurality of Josephson junctions connected in series. The plurality of Josephson junctions includes a first Josephson junction, which includes a first superconducting electrode on a surface of a substrate, a second superconducting electrode that overlaps the first superconducting electrode, and a barrier sandwiched between overlapping sections of the first and second superconducting electrodes. The barrier defines a footprint with a tapered shape over the surface of the substrate.

A method of manufacturing a travelling wave parametric amplifier (TWPA) includes forming a superconducting junction on a substrate. Trenches are etched away through a metal surface and into a layer of dielectric material. The trenches define a plurality of fingers positioned in an interdigitated arrangement of capacitors defined by a metal and a dielectric material that remains from the etched away metal surface and the layer of dielectric material.

A method of manufacturing a travelling wave parametric amplifier (TWPA) includes forming a superconducting junction on a substrate. Trenches are etched away through a metal surface and into a layer of dielectric material. The trenches define a plurality of fingers positioned in an interdigitated arrangement of capacitors defined by a metal and a dielectric material that remains from the etched away metal surface and the layer of dielectric material.

A bandpass parametric amplifier circuit includes a plurality of unit cells. At least one unit cell includes a first inductor having a first node coupled to a center conductor and a second node coupled to ground. There is a first capacitor having a first node coupled to the center conductor and a second node coupled to ground. There is a second inductor having a first node coupled to the center conductor. A second capacitor has a first node coupled to a second node of the second inductor. The second capacitor and the second inductor are in series with the center conductor.

A bandpass parametric amplifier circuit includes a plurality of unit cells. At least one unit cell includes a first inductor having a first node coupled to a center conductor and a second node coupled to ground. There is a first capacitor having a first node coupled to the center conductor and a second node coupled to ground. There is a second inductor having a first node coupled to the center conductor. A second capacitor has a first node coupled to a second node of the second inductor. The second capacitor and the second inductor are in series with the center conductor.

A quantum parameter amplifier; the quantum parameter amplifier includes a capacitor module, a first microwave resonant cavity, and an inductance-adjustable superconducting quantum interference apparatus that are connected in sequence to constitute an oscillation amplifier circuit, wherein, the superconducting quantum interference apparatus is grounded; the quantum parameter amplifier further includes a voltage modulating circuit and/or a second microwave resonant cavity; one end of the voltage modulating circuit is connected with an end of the superconducting quantum interference apparatus that is close to the first microwave resonant cavity; and one end of the second microwave resonant cavity is connected with the end of the superconducting quantum interference apparatus that is close to the first microwave resonant cavity. A frequency of a pump signal that makes the quantum parameter amplifier according to the present disclosure in an optimal operation mode does not need to be selected as a multiple of a frequency of the signal to be amplified.

A quantum parameter amplifier; the quantum parameter amplifier includes a capacitor module, a first microwave resonant cavity, and an inductance-adjustable superconducting quantum interference apparatus that are connected in sequence to constitute an oscillation amplifier circuit, wherein, the superconducting quantum interference apparatus is grounded; the quantum parameter amplifier further includes a voltage modulating circuit and/or a second microwave resonant cavity; one end of the voltage modulating circuit is connected with an end of the superconducting quantum interference apparatus that is close to the first microwave resonant cavity; and one end of the second microwave resonant cavity is connected with the end of the superconducting quantum interference apparatus that is close to the first microwave resonant cavity. A frequency of a pump signal that makes the quantum parameter amplifier according to the present disclosure in an optimal operation mode does not need to be selected as a multiple of a frequency of the signal to be amplified.

The present disclosure relates to a kinetic inductance parametric amplifier that comprises an input port arranged to receive a pump tone, a DC bias and input signal; an output port arranged to provide an amplified version of the input signal; a tunable stepped-impedance assembly arranged to attenuate and/or filter predetermined frequency bands; and a high kinetic inductance line. The tunable stepped-impedance assembly is tuned at a frequency that allows for the amplifier to resonate at a predetermined frequency and a pump tone with a frequency higher than the input signal and a DC biasing signal to be transmitted to the high kinetic inductance line.

The present disclosure relates to a kinetic inductance parametric amplifier that comprises an input port arranged to receive a pump tone, a DC bias and input signal; an output port arranged to provide an amplified version of the input signal; a tunable stepped-impedance assembly arranged to attenuate and/or filter predetermined frequency bands; and a high kinetic inductance line. The tunable stepped-impedance assembly is tuned at a frequency that allows for the amplifier to resonate at a predetermined frequency and a pump tone with a frequency higher than the input signal and a DC biasing signal to be transmitted to the high kinetic inductance line.

A signal amplifier is distributed between first and second IC devices and includes a low-power input stage disposed within the first IC device, a bias-current source disposed within the second IC device and an output stage disposed within the second IC device. The output stage includes a resistance disposed within the second IC device and having a first terminal coupled to a drain terminal of a transistor within the input stage via a first signaling line that extends between the first and second IC devices.