Google Inc.

Theodore Charles White

Anthony Edward Megrant

Ofer Naaman

Julian Shaw Kelly

John Martinis

Brian James Burkett

Evan Jeffrey

A parametric traveling wave amplifier () is disclosed in which the amplifiers include: a co-planar waveguide, in which the co-planar waveguide includes at least one Josephson junction () interrupting a center trace () of the co-planar waveguide; and at least one shunt capacitor coupled to the co-planar waveguide, in which each shunt capacitor of the at least one shunt capacitor includes a corresponding superconductor trace () extending over an upper surface of the center trace of the co-planar waveguide, and in which a gap separates the superconductor trace from the upper surface of the center trace, and in which the co-planar waveguide including the at least one Josephson junction and the shunt capacitor establish a predefined overall impedance for the traveling wave parametric amplifier.

Parametric traveling wave amplifier for qubits

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 integrated qubit readout circuit is presented, which includes a superconducting parametric amplifier, a circuit board arranged to mount the superconducting parametric amplifier, a circulator mounted on the circuit board and connected to the superconducting parametric amplifier, wherein the circulator comprises a termination port electrically connected to a termination resistor arranged to terminate a pump tone received by the superconducting parametric amplifier, and wherein the termination resistor is mounted on the circuit board.

Integrated readout card

A device includes: a first chip including a qubit; and a second chip bonded to the first chip, the second chip including a substrate including first and second opposing surfaces, the first surface facing the first chip, wherein the second chip includes a single layer of superconductor material on the first surface of the substrate, the single layer of superconductor material including a first circuit element. The second chip further includes a second layer on the second surface of the substrate, the second layer including a second circuit element. The second chip further includes a through connector that extends from the first surface of the substrate to the second surface of the substrate and electrically connects a portion of the single layer of superconducting material to the second circuit element.

Reducing loss in stacked quantum devices

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

A quantum computing devices includes: a qubit; a readout device coupled to the qubit, the readout device including a frequency filter having a filter frequency range; and an amplifier device coupled to the readout device, in which the amplifier device is configured to amplify a measurement signal from the readout device upon receiving a pump signal having a pump frequency that is outside of the filter frequency range of the frequency filter.

Amplifier frequency matching for qubit readout

A device includes: a substrate; a first superconductor layer on the substrate, the first superconductor layer having a first kinetic inductance; and a second superconductor layer on the first superconductor layer, the second superconductor layer having a second kinetic inductance that is lower than the first kinetic inductance, in which the second superconductor layer covers the first superconductor layer such that the second superconductor layer and the first superconductor layer have a same footprint, with the exception of at least a first region where the second superconductor layer is omitted so that the first superconductor layer and the second superconductor layer form a circuit element having a predetermined circuit parameter.

Hybrid kinetic inductance devices for superconducting quantum computing

The proposed device includes a first chip () comprising a superconducting quantum bit and a second chip () bonded to the first chip, the second chip including a substrate () having first and second opposing surfaces. The first surface () facing the first chip includes a layer () of superconductor material which includes a first circuit element. The second chip further includes a second layer () on the second surface () which includes a second circuit element, and a through connector () that extends from the first surface to the second surface and electrically connects a portion of the superconductor material layer to the second circuit element.

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Santa Barbara, CA, United States of America

Theodore Charles White