Mode-selective couplers for frequency collision reduction

Patent metadata

Field	Value
Publication number	US-12120965-B2
Application number	US-202318160465-A
Country	US
Kind code	B2
Filing date	Jan 27, 2023
Priority date	Jun 8, 2020
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

Systems and techniques that facilitate mode-selective couplers for frequency collision reduction are provided. In various embodiments, a device can comprise a control qubit. In various aspects, the device can comprise a first target qubit coupled to the control qubit by a first mode-selective coupler. In various instances, the first mode-selective coupler can facilitate A-mode coupling between the control qubit and the first target qubit. In various embodiments, the device can comprise a second target qubit coupled to the control qubit by a second mode-selective coupler. In various aspects, the second mode selective coupler can facilitate B-mode coupling between the control qubit and the second target qubit. In various embodiments, the first mode-selective coupler can comprise a capacitor that capacitively couples a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit. In various embodiments, the second mode-selective coupler can comprise a first capacitor that capacitively couples an end capacitor pad of the control qubit to an end capacitor pad of the first target qubit and can comprise a second capacitor that capacitively couples the end capacitor pad of the control qubit to a middle capacitor pad of the second target qubit.

First claim

What is claimed is:

1. A device, comprising:
a control qubit coupled to a first mode-selective coupler, a second mode-selective coupler, a third mode-selective coupler, and a fourth mode-selective coupler;
a first target qubit coupled to the first mode-selective coupler, wherein the first mode-selective coupler allows A-mode coupling between the control qubit and the first target qubit, and prevents B-mode coupling between the control qubit and the first target qubit;
a second target qubit coupled to the second mode-selective coupler, wherein the second mode-selective coupler allows the B-mode coupling between the control qubit and the second target qubit, and prevents the A-mode coupling between the control qubit and the second target qubit;
a third target qubit coupled to the third mode-selective coupler, wherein the third mode-selective coupler allows A-mode coupling between the control qubit and the third target qubit, and prevents B-mode coupling between the control qubit and the third target qubit; and
a fourth target qubit coupled to the fourth mode-selective coupler, wherein the fourth mode-selective coupler allows the B-mode coupling between the control qubit and the second target qubit, and prevents the A-mode coupling between the control qubit and the fourth target qubit.

2. The device of claim 1 , wherein the first target qubit is degenerate with respect to the second target qubit.

3. The device of claim 1 , wherein the third target qubit is degenerate with respect to the fourth target qubit.

4. The device of claim 1 , wherein the first target qubit and the second target qubit are non-degenerate with respect to the third target qubit and the fourth target qubit.

5. The device of claim 1 , wherein at least one of the control qubit, the first target qubit, the second target qubit, the third target qubit, or the fourth target qubit is a two-junction transmon qubit.

6. The device of claim 1 , wherein the control qubit is entangled with at least one of the first target qubit or the third target qubit in response to the control qubit being driven by a microwave tone corresponding to an A-mode excitation frequency.

7. The device of claim 6 , wherein the control qubit is entangled with at least one of the second target qubit or the fourth target qubit in response to the control qubit being driven by a microwave tone corresponding to an B-mode excitation frequency.

8. A method, comprising:
coupling a control qubit to a first target qubit by a first mode-selective coupler that allows A-mode coupling between the control qubit and the first target qubit, and prevents B-mode coupling between the control qubit and the first target qubit;
coupling the control qubit to a second target qubit by a second mode-selective coupler that allows the B-mode coupling between the control qubit and the second target qubit, and prevents the A-mode coupling between the control qubit and the second target qubit;
coupling the control qubit to a third target qubit by a third mode-selective coupler that allows the A-mode coupling between the control qubit and the third target qubit, and prevents the B-mode coupling between the control qubit and the third target qubit; and
coupling the control qubit to and a fourth target qubit by a fourth mode-selective coupler that allows the B-mode coupling between the control qubit and the fourth target qubit, and prevents the A-mode coupling between the control qubit and the fourth target qubit.

9. The method of claim 8 , wherein the first target qubit is degenerate with respect to the second target qubit.

10. The method of claim 8 , wherein the third target qubit is degenerate with respect to the fourth target qubit.

11. The method of claim 8 , wherein the first target qubit and the second target qubit are non-degenerate with respect to the third target qubit and the fourth target qubit.

12. The method of claim 8 , wherein at least one of the control qubit, the first target qubit, the second target qubit, the third target qubit, or the fourth target qubit is a two-junction transmon qubit.

13. The method of claim 8 , wherein the control qubit is entangled with at least one of the first target qubit or the third target qubit in response to the control qubit being driven by a microwave tone corresponding to an A-mode excitation frequency.

14. The method of claim 13 , wherein the control qubit is entangled with at least one of the second target qubit or the fourth target qubit in response to the control qubit being driven by a microwave tone corresponding to an B-mode excitation frequency.

15. A computer program product for facilitating selectively coupling a control qubit to target qubits, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
couple the control qubit to a first target qubit by a first mode-selective coupler that allows A-mode coupling between the control qubit and the first target qubit, and prevents B-mode coupling between the control qubit and the first target qubit;
couple the control qubit to a second target qubit by a second mode-selective coupler that allows the B-mode coupling between the control qubit and the second target qubit, and prevents the A-mode coupling between the control qubit and the second target qubit;
couple the control qubit to a third target qubit by a third mode-selective coupler that allows the A-mode coupling between the control qubit and the third target qubit, and prevents the B-mode coupling between the control qubit and the third target qubit; and
couple the control qubit to a fourth target qubit by a fourth mode-selective coupler that allows the B-mode coupling between the control qubit and the fourth target qubit, and prevents the A-mode coupling between the control qubit and the fourth target qubit.

16. The computer program product of claim 15 , wherein the first target qubit is degenerate with respect to the second target qubit.

17. The computer program product of claim 15 , wherein the third target qubit is degenerate with respect to the fourth target qubit.

18. The computer program product of claim 15 , wherein the first target qubit and the second target qubit are non-degenerate with respect to the third target qubit and the fourth target qubit.

19. The computer program product of claim 15 , wherein at least one of the control qubit, the first target qubit, the second target qubit, the third target qubit, or the fourth target qubit is a two-junction transmon qubit.

20. The computer program product of claim 15 , wherein the control qubit is entangled with at least one of the first target qubit or the third target qubit in response to the control qubit being driven by a microwave tone corresponding to an A-mode excitation frequency, and
wherein the control qubit is entangled with at least one of the second target qubit or the fourth target qubit in response to the control qubit being driven by a microwave tone corresponding to an B-mode excitation frequency.

Assignees

• IBM

Inventors

• Finck Aaron
• Blair John

Classifications

• G06N10/40

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

• H10N69/00 Primary

  Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00 · CPC title

• H10N60/805 Primary

  for Josephson-effect devices · CPC title

• H10N60/12 Primary

  Josephson-effect devices · CPC title

• B82Y10/00

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title