A circuit configured to transmit frequency multiplexed signals from a superconducting domain to a higher temperature domain. The circuit comprising a multiplexed signal output and a plurality of superconducting oscillator circuits each configured to output a different carrier frequency, each superconducting oscillator circuit comprising an oscillator output connected to the multiplexed signal output. Each superconducting oscillator circuit comprising a converter stage configured to convert an input of a superconducting logic signal to a Single Flux Quantum (SFQ) bit value, a splitter stage electrically connected to an output of the converter stage, the splitter stage configured to change between a first current state and a second current state based at least in part on the SFQ bit value, and an oscillator stage magnetically coupled to an output of the splitter stage and electrically coupled to the oscillator output. The oscillator stage comprising a direct current superconducting quantum interference device (DC SQUID).

One or more systems, devices, methods of use and/or methods of fabrication provided herein relate to a device that can facilitate qubit measurement with isolation imposed between a quantum processor and a respective qubit measurement circuit and/or which respective qubit measurement circuit can have a small footprint, such as within a respective cryogenic chamber of a quantum system. According to one embodiment, a device comprises an isolator circuit having a bandpass filter configuration coupled between a pair of ports and the bandpass filter configuration comprising two or more poles. Two or more shunt resonators can be realized as the two or more poles, wherein the two or more shunt resonators can comprise DC SQUIDs and can be coupled together with one or more admittance inverters. A non-reciprocal signal transmission can be generated between the two ports by RF pumping the DC SQUIDs.

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.

Superconducting output amplifiers having return to zero to non-return to zero converters are described. An example superconducting output amplifier (OA) includes a first superconducting OA stage having a first DC-SQUID and a second DC-SQUID arranged in parallel to the first DC-SQUID. The superconducting OA includes an input terminal for receiving a single flux quantum (SFQ) pulse train. The superconducting OA includes a first splitter configured to split a first set of SFQ pulses corresponding to the SFQ pulse train into a first return to zero (RZ) signal and a second RZ signal. The superconducting OA includes a first return to zero to non-return to zero (RZ- NRZ) converter configured to convert the first RZ signal into a first non-return to zero (NRZ) signal for driving the first DC-SQUID, and a second RZ-NRZ converter configured to convert the second RZ signal into a second NRZ signal for driving the second DC-SQUID.

A receiver for detecting at least one electromagnetic signal while the receiver is moving relative to the Earth's magnetic field, the receiver comprising: an SQUID array for generating an output that is a transfer function of SQUID array magnetic flux that is supplied from a combination of an oscillating magnetic field of the at least one electromagnetic signal, the Earth's magnetic field, and a bias magnetic field; a bias-tee configured to divide the SQUID array output into a DC signal and an RF signal; a memory store configured to store a plurality of voltage and flux bias values, wherein each voltage value has a corresponding flux bias value that results in maximum SQUID array sensitivity; and a logic circuit configured to find a voltage value in the memory store that most closely matches the DC signal, and to apply to the SQUID array a flux bias corresponding to the most closely matched voltage value.

A hybrid Bacon-Shor surface code is implemented using a fault tolerant quantum computer comprising hybrid acoustic-electric qubits. A control circuit includes an asymmetrically threaded superconducting quantum interference devices (ATS) that excites phonons in a mechanical resonator by driving a storage mode of the mechanical resonator and dissipates phonons from the mechanical resonator via an open transmission line coupled to the control circuit. The hybrid Bacon-Shor surface code only couples four phononic modes per given ATS, reducing cross-talk as compared to other systems that couple more phononic modes per ATS. Also, measurements are performed such that three parity measurements are taken between a phononic readout mode and a transmon qubit in a given syndrome measurement cycle.

A dual-helmet magnetoencephalography measuring apparatus includes: an internal container storing a liquid refrigerant; an external container disposed to surround the internal container and including a first external helmet and a second external helmet disposed to be spaced apart from each other; a first sensor-mounted helmet disposed to surround the first external helmet between the external container and the internal container; a second sensor-mounted helmet disposed to surround the second external helmet between the externa container and the internal container; a plurality of first SQUID sensor module disposed on the first sensor-mounted helmet; and a plurality of second SQUID sensor module disposed on the second sensor-mounted helmet.

The present disclosure relates to improved electronic structures for propagating logic states between superconducting digital logic gates using a three-junction interferometer in a receiver circuit to reduce reflecting signals that otherwise result in distortions in the signals being transmitted between the gates. Other improved electronic structures comprise passive transmission lines (PTLs) with transmission line matching circuitry that has previously been avoided. The matching circuity minimizes generation and propagation of spurious pulses emitted by Josephson junctions used in the digital logic gates.

The present disclosure relates to improved electronic structures for propagating logic states between superconducting digital logic gates using a three-junction interferometer in a receiver circuit to reduce reflecting signals that otherwise result in distortions in the signals being transmitted between the gates. Other improved electronic structures comprise passive transmission lines (PTLs) with transmission line matching circuitry that has previously been avoided. The matching circuity minimizes generation and propagation of spurious pulses emitted by Josephson junctions used in the digital logic gates.

A receiver for detecting at least one electromagnetic signal while the receiver is moving relative to the Earth's magnetic field, the receiver comprising: an SQUID array for generating an output that is a transfer function of SQUID array magnetic flux that is supplied from a combination of an oscillating magnetic field of the at least one electromagnetic signal, the Earth's magnetic field, and a bias magnetic field; a bias-tee configured to divide the SQUID array output into a DC signal and an RF signal; a memory store configured to store a plurality of voltage and flux bias values, wherein each voltage value has a corresponding flux bias value that results in maximum SQUID array sensitivity; and a logic circuit configured to find a voltage value in the memory store that most closely matches the DC signal, and to apply to the SQUID array a flux bias corresponding to the most closely matched voltage value.