International Business Machines Corporation

Matthew Beck

Michael Karunendra Selvanayagam

John Francis Bulzacchelli

Corrado P Mancini

Daniel Joseph Friedman

Sergey Vladimirovich Rylov

Raphael Peter Robertazzi

John Timmerwilke

Joseph Robert Suttle

Marco Turchetti

Santino Carnevale

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.

Quantum architecture biasing scheme

A device comprises filter circuitry and non-linear mixing devices. The filter circuitry comprises a first port, a second port, a first bandpass filter, and a second bandpass filter. The non-linear mixing devices are responsive to control signals to couple poles of the first bandpass filter to respective poles of the second bandpass filter to cause non-reciprocal transmission of signals from the first port to the second port.

Multipole multiband isolator devices

A device comprises a superconducting parametric interferometric circuit, which comprises a signal input port and a signal output port, and a first parametric mixing circuit and a second parametric mixing circuit coupled in parallel between the signal input port and the signal output port. The signal input port configured to receive an input signal having a first frequency. The first parametric mixing circuit is configured to convert the input signal to a first output signal having a second frequency, and the second parametric mixing circuit is configured to convert the input signal to a second output signal having the second frequency. The superconducting parametric interferometric circuit is configured to constructively combine the first and second output signals at the signal output port to generate an output signal having the second frequency, and provide isolation of the signal input port from a signal which is present at the signal output port.

Superconducting parametric interferometers for isolation and directional amplification

A device comprises a switch circuit and control lines. The switch circuit comprises a plurality of signal input/output ports, and a plurality of switch nodes, each switch node comprising a superconducting loop which comprises a plurality of Josephson junctions arranged in a ring configuration. The control lines are configured to selectively apply flux bias control signals to the switch nodes. The plurality of switch nodes is arranged to selectively configure a signal routing path between any pairwise combination of signal input/output ports of the plurality of signal input/output ports, in response to flux bias control signals selectively applied to the switch nodes.

Superconducting multi-way switches

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.

Quantum circuit with Josephson multipole isolator

A device includes a logic circuit comprising a clockless single flux quantum logic gate which comprises a plurality of input ports, an output port, an output Josephson junction, and a plurality of dynamic storage loop circuits and isolation buffer circuits. The output Josephson junction is coupled to an output of each dynamic storage loop circuit and configured to drive the output port. Each isolation buffer circuit is coupled to a respective input port, and a respective dynamic storage loop circuit and configured to absorb a circulating current of an antifluxon which is injected into the respective dynamic storage loop circuit to prevent the antifluxon from being output from the respective input port, and to inject a fluxon into the respective dynamic storage loop circuit in response to a single flux quantum pulse applied to the respective input port, and annihilate an antifluxon present in the respective dynamic storage loop circuit.

Metastability-free clockless single flux quantum logic circuitry

A system comprises a superconducting quantizing inductor and superconducting control circuitry, which is coupled to the superconducting quantizing inductor to form a superconducting loop, and which is configured to selectively inject a quantized amount of positive or negative current into the superconducting loop to generate a quantized circulating current in the superconducting loop. The quantized circulating current comprises a time-varying or static circulating current. The superconducting control circuitry comprises first and second current generator circuits which comprise a first and second plurality of Josephson junctions, respectively, which are configured to inject quantized amounts of positive current and negative current into the superconducting loop in response to single flux quantum pulses. The first and second current generator circuits comprise respective first and second current distribution networks that are configured to distribute circulating current in the superconducting loop to the respective Josephson junctions without causing switching of the Josephson junctions.

Single flux quantum circuitry for quantized flux bias control

Techniques facilitating a quantum gate between qubits using a tunable coupler are provided. In one example, a quantum coupler device can comprise a Josephson ring modulator (JRM) that is operatively coupled to first and second qubits in a balanced bridge topology via respective first and second capacitive devices. The JRM provides tunable coupling between the first and second qubits.

Josephson double balanced coupler

A method of using Josephson Junctions to convert the envelope of radio-frequency signals into baseband control pulses includes injecting a biasing current into an envelope detector circuit. The biasing current is identified based on first and second critical currents of superconducting devices in the envelope detector circuit. The first critical current corresponds to the envelope detector circuit receiving no RF signals. The second critical current corresponds to the envelope detector circuit receiving maximum RF signals. The method further includes receiving a modulated radio frequency (RF) signal at the envelope detector circuit to detect an envelope of the received RF signal. The output of the envelope detector circuit is used to drive an output load. The output is generated based on the detected envelope by the envelope detector circuit.

Josephson RF envelope-to-DC converter

One or more systems, devices and/or methods of use provided herein relate to a device that can facilitate selective switching between band pass and band stop filter modes and/or can provide reflectionless or near reflectionless function. A device can comprise a filter circuit coupled between a pair of ports and comprising a direct current superconducting quantum interference device (DC SQUID), wherein the filter circuit is selectively activatable by varying the inductance of the DC SQUID. Applying flux bias to the DC SQUID can allow for the switching between the band pass and band stop filter modes.

Josphson band pass to band stop filter

Radio-frequency (RF) to direct current (DC) converter and bipolar quantized supercurrent generator (QSG)

A method of generating an output signal based on a single flux quantum (SFQ) pulse includes receiving the SFQ pulse and splitting it into a first path and a second path. The split SFQ pulse of the second path is stored in a latch. A second splitting of the split SFQ pulse of the first path is provided to provide a first output signal and a second output signal of the first path. The second output signal is delayed by a delay Josephson transmission line (JTL). An output of the delay JTL is provided as a clock input to the latch. The first output of the first path is recombined with an output of the latch to provide an output signal.

Rapid single flux quantum pulse multiplier

A single flux quantum (SFQ) circuit includes a radio frequency (RF) to direct current (DC) conversion stage. A DC to RF current conversion stage is coupled to a single output of the RF to DC conversion stage. The DC to RF current conversion stage includes a plurality of series stacked Josephson Junctions (JJs) having n stages, configured to convert a DC current received from the RF to DC conversion stage and reconvert the DC current to an RF tone.

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Danbury, CT, United States of America

Matthew Beck