Northrop Grumman Systems Corporation

Google Inc.

Microsoft Technology Licensing, LLC

Michigan State University

Ofer Naaman

Donald Lynn Miller

David George Ferguson

Zachary Keane

Anna Y Herr

Quentin P Herr

Joel D Strand

Theodore Charles White

Mohamed Osama Abutaleb

Zachary Kyle Keane

Anthony Edward Megrant

Randall M Burnett

Joshua A Strong

Anthony Joseph Przybysz

Micah John Atman Stoutimore

Brian James Burkett

Rupert M Lewis

Henry Y Luo

Aaron A Pesetski

Evan Jeffrey

Jonathan D Egan

Andrew Hostetler Miklich

Bryan K Eastin

Jae I Park

Micah Stoutimore

Steven L Sendelbach

Norman O Birge

Mohamed O Abutaleb

Micah John Stoutimore

Henry Yu Tsing Luo

A Josephson parametric device is presented, which includes an input port, an output port, and a signal path between the input port and the output port. The signal path includes a first section coupled to the input port and having a first passband, a second section coupled to the output port and having a second passband and a Josephson junction coupling element for parametric coupling between the first and second section. The Josephson junction coupling element is coupled to and interposed between the first section and the second section. The Josephson junction coupling element is configured such that, in response to the input port receiving a first signal at a first frequency lying within the first passband and the Josephson junction coupling element receiving a pump tone, the Josephson junction coupling element converts the first signal into a second signal with a second frequency lying within the second passband.

Josephson parametric coupler

A Josephson parametric device (e.g., a circulator/isolator or directional amplifier) can include a plurality of resonant modes, a plurality of couplings, an input port and an output port. The plurality of resonant modes includes first, second, and third resonant modes, the first and third resonant modes both configured to operate at a first resonant frequency and the second resonant mode configured to operate at a second resonant frequency that is different than the first resonant frequency. The plurality of couplings includes a passive coupling between the first and third resonant modes, a first parametric coupling between the first and second resonant modes, and a second parametric coupling between the second and third resonant modes. The input port is coupled to the first resonant mode of the device, and the output port is coupled to the third resonant mode of the device.

Josephson parametric devices having same-frequency ports

Methods, systems and apparatus for forming Josephson junctions with reduced stray inductance. In one aspect, a device includes a substrate; a first superconductor layer on the substrate; an insulator layer on the first superconductor layer; a second superconductor layer on the insulator layer, wherein the first superconductor layer, the insulator layer, and the second superconductor layer form a superconductor tunnel junction; and a third superconductor layer directly on a surface of the first superconductor layer and directly on a surface of the second superconductor layer to provide a first contact to the superconducting tunnel junction and a second contact to the superconductor tunnel junction, respectively.

Josephson junctions with reduced stray inductance

An apparatus includes a directional coupler and an absorptive low pass filter, in which the directional coupler has a first transmission line extending from a first port to a second port and a second transmission line extending from a third port to a fourth port, the first transmission line and the second transmission line configured such that a portion of a signal travelling from the first port onto the first transmission line is coupled to the second transmission line and towards the third port. The second port is connected to the fourth port of the directional coupler via the absorptive low pass filter. When the signal is input into the first port of the directional coupler and output through the third port of the directional coupler, the signal is substantially unattenuated if the frequency of the signal is in a passband of the absorptive low pass filter.

Attenuator for qubit drive signals

A circuit is presented which includes a first amplifier having an input, a transmission line having first and second ends. The first end of the transmission line is coupled to an input of the first amplifier and a plurality of channels. Each channel includes a plurality of resonators arranged to read out a plurality of qubits, respectively and a readout line arranged to receive read out signals from the plurality of resonators. The readout line of each channel is coupled to the transmission line and each channel is configured to output a respective signal in a respective frequency band which is different from frequency bands of other channels in the plurality of channels.

Multiplexed readout system

The technology relates to quantum computing devices and test arrangements for detecting information from the qubits of such devices. According to aspects of the technology, a Purcell filter is structured in a multi-pole architecture to provide a sharper filter response having a flatter signal pass band, sharper turn-off skirt, and enhanced out of band rejection. The system is able to determine the states of the qubits by detecting the frequency of the readout resonators of the test arrangement. The Purcell filter is configured to be sharply tuned to enable faster readout to avoid issues associated with a longer relaxation time (T1) of the qubits.

Purcell filter having prescribed transfer characteristics

One example includes a memory cell system. The memory cell system includes a quantizing loop configured to conduct a quantizing current in a first direction corresponding to storage of a first state of a stored memory state of the memory cell system and to conduct the quantizing current in a second direction opposite the first direction corresponding to storage of a second state of the stored memory state of the memory cell system. The memory cell system also includes a bias element arranged in the quantizing loop and which is configured to provide a substantially constant flux bias of the quantizing loop in each of the first and second states of the stored memory state.

Quantizing loop memory cell system

One example includes a memory cell system that includes a quantizing loop that conducts a quantizing current in a first direction corresponding to a first stored memory state and to conduct the quantizing current in a second direction corresponding to a second stored memory state. The system also includes a bias element configured to provide a substantially constant flux bias of the quantizing loop in each of the first and second states of the stored memory state. The stored memory state can be read from the memory cell system in response to the substantially constant flux bias and a read current that is provided to the memory cell system. The system further includes a tunable energy element that is responsive to a write current that is provided to the memory cell system to change the state of the stored memory state between the first state and the second state.

Examples described in this disclosure relate to a memory cell with Josephson phase-based torque. In one example, a memory cell including a first inductor and a magnetic Josephson junction (MJJ) coupled to the first inductor to form a loop is provided. The MJJ may include a free magnetic layer formed above a non-magnetic layer, and a fixed magnetic layer below the non-magnetic layer. A first state of the memory cell corresponds to a first magnetization of the free magnetic layer that is parallel to a magnetization of the fixed magnetic layer and the second state of the memory cell corresponds to a second magnetization of the free magnetic layer that is anti-parallel to the magnetization of the fixed magnetic layer. The memory cell is configured to switch from the first state to the second state based on whether the MJJ is in a zero-state or a &#x3c0;-state.

Superconducting memory with josephson phase-based torque

One example includes a superconducting bidirectional current driver. The current driver includes a first direction superconducting latch that is activated in response to a first activation signal to provide a first current path of an input current through a bidirectional current load in a first direction. The current driver also includes a second direction superconducting latch that is activated in response to a second activation signal to provide a second current path of the input current through the bidirectional current load in a second direction opposite the first direction.

Superconducting bi-directional current driver

Real-time reconfigurability of quantum object connectivity can be provided with one or more quantum routers that can each be configured as either or both of a single-pole double-throw switch and a cross-point switch. The quantum router includes variable-inductance coupling elements in RF-SQUIDs having inductors transformer-coupled to two control flux lines, one providing a static current and the other providing a dynamic current, the direction of which can be toggled to couple or uncouple quantum objects, such as qubits, based on the dynamic current direction to provide reconfigurable quantum routing.

Reconfigurable quantum routing

One example includes a parametric amplifier system. The system includes an input/output (I/O) transmission line to propagate a signal tone. The system also includes a non-linearity circuit comprising at least one Josephson junction to provide at least one inductive path of the signal tone in parallel with the at least one Josephson junction. The system further includes an impedance matching network coupled to the I/O transmission line to provide impedance matching of the tone signal between the I/O transmission line and the non-linearity element.

Parametric amplifier system

One embodiment describes a Josephson transmission line (JTL) system. The system includes a plurality of JTL stages that are arranged in series. The system also includes a clock transformer comprising a primary inductor configured to propagate an AC clock signal and a secondary inductor arranged in a series loop with at least two of the plurality of JTL stages. The clock transformer can be configured to propagate a single flux quantum (SFQ) pulse to set a respective one of the plurality of JTL stages in response to a first phase of the AC clock signal and to reset the respective one of the plurality of JTL stages in response to a second phase of the AC clock signal that is opposite the first phase.

Josephson transmission line (JTL) system

A tunable bus-mediated coupling system is provided that includes a first input port coupled to a first end of a variable inductance coupling element through a first resonator and a second input port coupled to a second end of the variable inductance coupling element through a second resonator. The first input port is configured to be coupled to a first qubit, and the second output port is configured to be coupled to a second qubit. A controller is configured to control the inductance of the variable inductance coupling element between a low inductance state to provide strong coupling between the first qubit and the second qubit and a high inductance state to provide isolation between the first qubit and the second qubit.

Growing community of inventors

Ellicott City, MD, United States of America

Ofer Naaman