Superconducting qubit and resonator system based on the Josephson ring modulator

Patent metadata

Field	Value
Publication number	US-11552239-B2
Application number	US-201916698216-A
Country	US
Kind code	B2
Filing date	Nov 27, 2019
Priority date	Nov 27, 2019
Publication date	Jan 10, 2023
Grant date	Jan 10, 2023

Abstract

A superconducting quantum mechanical device includes first, second, third and fourth Josephson junctions connected in a bridge circuit having first, second and third resonance eigenmodes. The device also includes first and second capacitor pads. The first and second capacitor pads and the bridge circuit form a superconducting qubit having a resonance frequency corresponding to the first resonance eigenmode. The device further includes first and second resonator sections. The first and second resonator sections and the bridge circuit form a resonator having a resonance frequency corresponding to the second resonance eigenmode. The device also includes a source of magnetic flux arranged proximate the bridge circuit. The source of magnetic flux is configured to provide, during operation, a magnetic flux through the bridge circuit to cause coupling between the first, second and third resonance eigenmodes when the third resonance eigenmode is excited.

First claim

I claim:

1. A superconducting quantum-mechanical device, comprising:
a first Josephson junction, a second Josephson junction electrically connected to the first Josephson junction, a third Josephson junction electrically connected to the second Josephson junction and a fourth Josephson junction electrically connected to the third Josephson junction and the first Josephson junction, wherein the first Josephson junction, the second Josephson junction, the third Josephson junction, and the fourth Josephson junction are connected in a bridge circuit having a first resonance eigenmode, a second resonance eigenmode and a third resonance eigenmode;
a first capacitor pad electrically connected to the first Josephson junction and the fourth Josephson junctions at a first node therebetween, and a second capacitor pad electrically connected to the second Josephson junction and the third Josephson junctions at a second node therebetween, wherein the first capacitor pad, the second capacitor pad, and the bridge circuit form a superconducting qubit having a first resonance frequency corresponding to the first resonance eigenmode of the bridge circuit;
a first resonator section electrically connected to the first Josephson junction and the second Josephson junctions at a third node therebetween, and a second resonator section electrically connected to the third Josephson junction and the fourth Josephson junctions at a fourth node therebetween, wherein the first resonator section, the second resonator section, and the bridge circuit form a resonator having a second resonance frequency corresponding to the second resonance eigenmode, wherein the first resonator section comprises a first resonator line, and wherein a first end portion of the first resonator line electrically connected to the third node is wider than other portions of first resonator line; and
a source of magnetic flux configured to provide, during operation, a magnetic flux through the bridge circuit to cause coupling between the first resonance eigenmode, the second resonance eigenmode, and the third resonance eigenmode when the third resonance eigenmode is excited.

2. The superconducting quantum-mechanical device according to claim 1 , wherein the source of magnetic flux comprises a current-carrying element that provides an electromagnetic source of magnetic flux that flux-biases the bridge circuit.

3. The superconducting quantum-mechanical device according to claim 1 , wherein the source of magnetic flux comprises a magnetic material that provides an electromagnetic source of magnetic flux that flux-biases the bridge circuit.

4. The superconducting quantum-mechanical device according to claim 1 , wherein the source of magnetic flux is controllable.

5. The superconducting quantum-mechanical device according to claim 1 ,
wherein the source of magnetic flux provides a half of flux quantum (cpo/2).

6. The superconducting quantum-mechanical device according to claim 1 , wherein the superconducting qubit is a transmon qubit.

7. The superconducting quantum-mechanical device according to claim 1 , wherein the second resonator section comprises a second resonator line that has a substantially equal length to the first resonator line.

8. The superconducting quantum-mechanical device according to claim 1 , wherein the first resonator line is arranged between electrically grounded pads.

9. The superconducting quantum-mechanical device according to claim 1 , further comprising a resonator feedline configured to be electromagnetically coupled to the resonator, wherein the resonator feedline provides a drive signal that excites the second resonance eigenmode during operation.

10. The superconducting quantum-mechanical device according to claim 8 , wherein the resonator feedline is separated from the resonator to define a capacitor therebetween.

11. The superconducting quantum-mechanical device according to claim 1 , further comprising a qubit feedline configured to be electromagnetically coupled to the superconducting qubit, wherein the qubit feedline provides a drive signal that excites the first resonance eigenmode during operation.

12. The superconducting quantum-mechanical device according to claim 10 , wherein the qubit feedline is separated from the superconducting qubit so as to define a capacitor therebetween.

13. The quantum device according to claim 1 , wherein the superconducting qubit and the resonator are formed on a same substrate and the bridge circuit is located substantially at a common center of the superconducting qubit and the resonator.

14. The superconducting quantum-mechanical device according to claim 1 , wherein the first resonator section, the second resonator section, the first Josephson junction, the second Josephson junction, the third Josephson junction and the fourth Josephson junction comprise a superconducting material selected from the group consisting of Al, Nb, NbTiN, NbN and TiN.

15. The superconducting quantum-mechanical device according to claim 1 , wherein the third resonance eigenmode is excited using a control drive signal applied to the superconducting qubit or the resonator.

16. The superconducting quantum-mechanical device according to claim 15 , wherein a frequency of the control drive signal is set to a difference between a qubit frequency of the superconducting qubit and the second resonance frequency of the resonator.

17. The superconducting quantum-mechanical device according to claim 15 , wherein an amplitude of the control drive signal is set to yield full frequency conversion between the superconducting qubit and the resonator.

18. The superconducting quantum-mechanical device according to claim 15 , wherein an amplitude of the control drive signal is set to yield 50:50 beam-splitting in which half of a qubit information is swapped with half of resonator information.

19. The superconducting quantum-mechanical device according to claim 15 , wherein a frequency of the control drive signal is set to a sum of a qubit frequency of the superconducting qubit and the second resonance frequency of the resonator and an amplitude of the control drive signal is set to yield two-mode squeezing of a qubit mode and a resonator mode.

20. The superconducting quantum-mechanical device according to claim 15 , wherein a frequency of the control drive signal is in the microwave frequency range.

Assignees

• IBM

Inventors

• Abdo Baleegh

Classifications

• H01P5/12 Primary

  Coupling devices having more than two ports (H01P5/04 takes precedence) · CPC title

• H03D7/005

  by means of superconductive devices · CPC title

• H03F19/00

  Amplifiers using superconductivity effects · CPC title

• H01L39/025

  Electricity · mapped topic

• G06N10/00

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