Compact multi-pole quantum bit measurement filter

Patent metadata

Field	Value
Publication number	US-2020320423-A1
Application number	US-201716768403-A
Country	US
Kind code	A1
Filing date	Dec 15, 2017
Priority date	Dec 15, 2017
Publication date	Oct 8, 2020
Grant date	—

Abstract

A system that includes: a qubit; a qubit readout resonator arranged adjacent to the qubit to couple to the qubit; and a first filter arranged adjacent to the qubit readout resonator to couple to the qubit readout resonator, the first filter comprising: a common port arranged to receive both a qubit readout resonator input drive signal and a measurement output signal from the qubit readout resonator, wherein the first filter is configured to impede at least one measurement photon emitted from the qubit is disclosed.

First claim

1 . A system comprising:
a qubit; a qubit readout resonator arranged adjacent to the qubit to couple to the qubit; and a first filter arranged adjacent to the qubit readout resonator to couple to the qubit readout resonator, the first filter comprising: a common port arranged to receive both a qubit readout resonator input drive signal and a measurement output signal from the qubit readout resonator, wherein the first filter is configured to impede at least one measurement photon emitted from the qubit, wherein the first filter comprises a first filter stub, a coupling portion and a second filter stub, wherein the first filter stub is disposed between the common port and a first side of the coupling portion and the second filter stub is disposed on a second side of the coupling portion, and wherein the qubit readout resonator is coupled to the coupling portion.

2 . The system of claim 1 , further comprising:
a circulator coupled to the common port, wherein the circulator is configured to separate an input drive signal from a measurement output signal on the common port.

3 . The system of claim 1 , further comprising:
a directional coupler coupled to the common port, wherein the directional coupler is configured to separate an input drive signal from a measurement output signal on the common port.

4 . The system of claim 1 , wherein the first filter comprises a bandpass filter.

5 . The system of claim 4 , wherein the bandpass filter is a Purcell filter.

6 . The system of claim 1 , wherein at least one of the qubit readout resonator or the first filter comprises a microwave resonator.

7 . The system of claim 6 , wherein the microwave resonator includes a co-planar waveguide resonator, a strip-line resonator, or a microstrip resonator.

8 . The system of claim 6 , wherein the qubit readout device and the first filter are formed from a superconductor.

9 . The system of claim 1 , wherein the qubit comprises a superconducting qubit or a spin qubit.

10 . The system of claim 1 , wherein the qubit comprises a qubit with a resonant frequency that is between 300 MHz and 300 GHz.

11 . The system of claim 1 , wherein the common port taps the first filter at a position such that the common port forms a stub filter between a first portion of the first filter and a second portion of the first filter.

12 . The system of claim 11 , wherein the stub filter includes at least one of a transmission-line filter or a lumped-element filter.

13 . The system of claim 11 , wherein the first filter is a half-wave coplanar waveguide filter, and
wherein the stub filter is a quarter-wave coplanar waveguide filter.

14 . The system of claim 11 , wherein a stop band of the stub filter is between 1 and 20 GHz.

15 . The system of claim 1 , further comprising:
a plurality of qubit devices, wherein each of the qubit devices includes:
another qubit,
another qubit readout resonator arranged adjacent to the qubit of the qubit device to couple to the qubit of the qubit device, and
another filter arranged adjacent to the qubit readout resonator of the qubit device to couple to the qubit readout resonator of the qubit device;
a common input port that is configured to receive a plurality of qubit readout resonator input drive signals for the plurality of qubit devices; and a switch that is configured to provide at least one of the plurality of qubit readout resonator input drive signals to at least one of the plurality of qubit devices.

16 . The system of claim 1 , further comprising:
a plurality of qubit devices, wherein each of the qubit devices has a respective resonator frequency and comprises:
another qubit,
another qubit readout resonator arranged adjacent to the qubit of the qubit device to couple to the qubit of the qubit device, and
another filter arranged adjacent to the qubit readout resonator of the qubit device to couple to the qubit readout resonator of the qubit device;
a common input port that is configured to receive a plurality of qubit readout resonator input drive signals for the plurality of qubit devices, wherein each of the plurality of qubit readout resonator input drive signals has a respective frequency; and a frequency domain multiplexer that is configured to provide, to a respective qubit device of the plurality of qubit devices, a first qubit readout resonator input drive signal of the plurality of qubit readout resonator input drive signals based on a frequency of the first qubit readout resonator input drive signal being matched to the respective resonator frequency of the qubit device.

17 . The system of claim 1 , further comprising:
an amplifier that is coupled to the common port and that is configured to amplify the measurement output signal from the qubit readout resonator.

18 . The system of claim 17 , wherein the amplifier includes a parametric amplifier or a High Electron Mobility Transistor amplifier.

19 . The system of claim 1 , further comprising:
a plurality of qubit devices, wherein each of the qubit devices includes:
another qubit, and
another qubit readout resonator arranged adjacent to the qubit of the qubit device to couple to the qubit of the qubit device;
wherein the first filter is arranged to couple to the qubit readout resonators of each of the plurality of the qubit devices.

Assignees

• Google Llc

Inventors

• Kelly Julian Shaw

Classifications

• G06N10/40 Primary

  Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control · CPC title

• G06N10/00 Primary

  Quantum computing, i.e. information processing based on quantum-mechanical phenomena · CPC title

• H01L39/02

  Electricity · mapped topic

• H10N60/80

  Constructional details · CPC title