A quantum computer hardware apparatus may include a first stage, which is connected to one or more signal generators, and a second stage adapted to be cooled down at a lower temperature than the first stage. Superconducting qubits are arranged in the second stage. The signal generators are configured, each, to generate radio frequency (RF) signals to drive the qubits, in operation. The apparatus may further include an intermediate stage between the first stage and the second stage, wherein the intermediate stage comprises one or more coolable filters, the latter configured for thermalizing RF signals from the signal generators. Related methods for thermalizing radio frequency signals in a quantum computer hardware apparatus are also disclosed.

A traveling wave parametric amplifier involving a series of Josephson junctions is disclosed. Devices and systems incorporating traveling wave parametric amplifiers, and methods of using and fabricating traveling wave parametric amplifiers are also disclosed.

A traveling wave parametric amplifier involving a series of Josephson junctions is disclosed. Devices and systems incorporating traveling wave parametric amplifiers, and methods of using and fabricating traveling wave parametric amplifiers are also disclosed.

Output amplifier comprising a stack of compound superconducting quantum interference device (SQUID) output amplifier stages and related methods are provided. A method includes receiving a first pulse train comprising a first plurality of single flux quantum (SFQ) pulses. The method may further include receiving a second pulse train comprising a second plurality of SFQ pulses, where the second pulse train is delayed by a predetermined fraction of a clock cycle relative to the first pulse train. The method may further include using the stack of the plurality of compound SQUID output amplifier stages converting the first plurality of SFQ pulses and the second plurality of SFQ pulses into a voltage waveform, where each of the plurality of compound SQUID output amplifier stages comprises a pair of superconducting quantum interference devices (SQUIDs).

Output amplifier comprising a stack of compound superconducting quantum interference device (SQUID) output amplifier stages and related methods are provided. A method includes receiving a first pulse train comprising a first plurality of single flux quantum (SFQ) pulses. The method may further include receiving a second pulse train comprising a second plurality of SFQ pulses, where the second pulse train is delayed by a predetermined fraction of a clock cycle relative to the first pulse train. The method may further include using the stack of the plurality of compound SQUID output amplifier stages converting the first plurality of SFQ pulses and the second plurality of SFQ pulses into a voltage waveform, where each of the plurality of compound SQUID output amplifier stages comprises a pair of superconducting quantum interference devices (SQUIDs).

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.

A quantum computer hardware apparatus may include a first stage, which is connected to one or more signal generators, and a second stage adapted to be cooled down at a lower temperature than the first stage. Superconducting qubits are arranged in the second stage. The signal generators are configured, each, to generate radio frequency (RF) signals to drive the qubits, in operation. The apparatus may further include an intermediate stage between the first stage and the second stage, wherein the intermediate stage comprises one or more coolable filters, the latter configured for thermalizing RF signals from the signal generators. Related methods for thermalizing radio frequency signals in a quantum computer hardware apparatus are also disclosed.

A system includes a first superconducting wire and a second superconducting wire connected in parallel. The system includes a first current source coupled to the first superconducting wire and configured to supply a first current in response to a trigger event. The system includes a second current source coupled in series with the parallel combination of the first superconducting wire and the second superconducting wire and configured to supply a second current. The superconducting wires are configured to, while receiving the second current, operate in a superconducting state in the absence of the first current. The first superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first current. The second superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first superconducting wire transitioning to the non-superconducting state.

A system includes a first superconducting wire and a second superconducting wire connected in parallel. The system includes a first current source coupled to the first superconducting wire and configured to supply a first current in response to a trigger event. The system includes a second current source coupled in series with the parallel combination of the first superconducting wire and the second superconducting wire and configured to supply a second current. The superconducting wires are configured to, while receiving the second current, operate in a superconducting state in the absence of the first current. The first superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first current. The second superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first superconducting wire transitioning to the non-superconducting state.

Techniques relate to an on-chip Josephson parametric converter. A Josephson ring modulator includes four nodes. A lossless on-chip flux line is capacitively coupled to two adjacent nodes of the four nodes of the Josephson ring modulator. The lossless on-chip flux line has an input port configured to receive a pump drive signal that couples differentially to the two adjacent nodes of the of the Josephson ring modulator. The pump drive signal thereby excites a common mode of the on-chip Josephson parametric converter.