Methods and structure to probe the metal-metal interface for superconducting circuits

Patent metadata

Field	Value
Publication number	US-11480537-B2
Application number	US-202016945549-A
Country	US
Kind code	B2
Filing date	Jul 31, 2020
Priority date	Jul 31, 2020
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A method of measuring contact resistance at an interface for superconducting circuits is provided. The method includes using a chain structure of superconductors to measure a contact resistance at a contact between contacting superconductor. The method further includes eliminating ohmic resistance from wire lengths in the chain structure by operating below the lowest superconducting transition temperature of all the superconductors in the chain structure. The measurement is dominated by contact resistances of the contacts between contacting superconductors in the chain.

First claim

We claim:

1. A method of measuring contact resistance at an interface for electronic circuits comprising:
providing a chain structure of conducting elements, the conducting elements arranged in series to contact adjacent conducting elements at respective contacts having respective contact resistances;
measuring a serial resistance of the chain structure at cryogenic temperatures; and
determining a contact resistance of the respective contacts between the conducting elements based on the measured serial resistance.

2. A method of measuring contact resistance at an interface for superconducting circuits comprising:
providing a chain structure of superconductors to measure a contact resistance at a contact between contacting superconductors;
eliminating ohmic resistance from wire lengths in the chain structure by operating below a lowest superconducting transition temperature of all the superconductors in the chain structure;
measuring a serial resistance of the chain structure; and
determining the contact resistance of the contact between the contacting superconductors based on the measured serial resistance of the chain structure,
wherein the measurement is dominated by contact resistances of the contacts between the contacting superconductors in the chain structure.

3. The method of claim 2 , wherein the superconductors of the chain structure of superconductors are made of a first superconducting material and a second superconducting material different from the first superconducting material.

4. The method of claim 3 , wherein the superconductors of the chain structure of superconductors are alternately arranged between superconductors of the first superconducting material and superconductors of the second superconducting material.

5. The method of claim 2 , wherein the contacting superconductors of the chain structure are shaped as wires.

6. A method of measuring contact resistance at an interface for superconducting circuits comprising:
providing a chain structure of superconducting elements, the superconducting elements arranged in series to contact adjacent superconducting elements at respective contacts having respective contact resistances;
operating the chain structure such that all of the superconducting elements are in a superconducting state; and
measuring a serial resistance of the chain structure while all of the superconducting elements are in a superconducting state; and
determining the contact resistance of the contacts between the contacting superconductors based on the measured serial resistance of the chain structure.

7. The method of claim 6 , further comprising calculating a number of contacts in the chain structure based on a resistance per contact and a noise level of a measurement instrument measuring the serial resistance.

8. The method of claim 6 , wherein the operating of the chain structure such that all of the superconducting elements are in a superconducting state comprises cooling the chain structure to a temperature below a superconducting transition temperature of all of the superconducting elements.

9. The method of claim 6 , wherein the superconducting elements of the chain structure of superconducting elements are made of a first superconducting material and a second superconducting material different from the first superconducting material.

10. The method of claim 9 , wherein the superconducting elements of the chain structure of superconducting elements are alternately arranged between superconducting elements of the first superconducting material and superconducting elements of the second superconducting material.

11. The method of claim 6 , wherein the superconducting elements of the chain structure are shaped as wires.

12. The method of claim 6 , wherein the number of superconducting elements of the chain structure is more than 10000.

13. A contact resistance measuring device comprising:
a chain structure of superconducting elements, the superconducting elements arranged in series to contact adjacent superconducting elements at respective contacts having respective contact resistances; and
a serial resistance measuring device arranged to measure a serial resistance of the chain structure while all of the superconducting elements in the chain structure are in a superconducting state,
wherein the serial resistance measuring device is configured to provide a contact resistance of contacts between the superconducting elements based on the measured serial resistance of the chain structure.

14. The contact resistance measuring device of claim 13 , further comprising a cryostat arranged to cool the chain structure such that all of the superconducting elements are in a superconducting state.

15. The contact resistance measuring device of claim 13 , wherein the chain structure further comprises a first conduction pad electrically connected to a first of the superconducting elements arranged in series and a last conduction pad electrically connected to a last of the superconducting elements arranged in series.

16. The contact resistance measuring device of claim 15 , wherein the chain structure further includes a first intermediate conduction pad electrically connected to a first intermediate of the superconducting elements arranged in series and a second intermediate conduction pad electrically connected to a second intermediate of the superconducting elements arranged in series.

17. The contact resistance measuring device of claim 16 , wherein the first intermediate conduction pad and the second intermediate conduction pad are adjacent to each other.

18. The contact resistance measuring device of claim 13 , wherein the superconducting elements are arranged in a first group and a second group.

19. The contact resistance measuring device of claim 18 , wherein each superconducting element of the first group contacts at least one superconducting element of the second group.

20. The contact resistance measuring device of claim 18 , wherein the superconducting elements of the first group are alternately arranged with superconducting elements of the second group.

21. The contact resistance measuring device of claim 18 , wherein the superconducting elements of at least one of the first group or the second group are all of a same length.

22. The contact resistance measuring device of claim 18 , wherein the superconducting elements of the first group are arranged in a direction perpendicular to a direction the superconducting elements of the second group are arranged.

23. The contact resistance measuring device of claim 18 , wherein the superconducting elements of the first group and the superconducting elements of the second group are shaped as wires, each wire having a first wire width of a first portion of the wire and a contact wire width of a second portion of the wire, the second portion of the wire contacting an adjacent wire.

24. The contact resistance measuring device of claim 23 , wherein the first wire width is greater than the contact wire width for at least one of the first group or the second group.

25. The contact resistance measuring device of claim 18 , further comprising a dielectric material arranged between the superconducting elements of the first group and the superconducting elements of the second group, the first group of superconducting elements contacting the second group of superconducting elements through respective holes in the dielectric material.

Assignees

• IBM

Inventors

• Lavoie Christian
• Brink Markus
• Wymore Benjamin
• Yau Jeng-Bang

Classifications

• G01N27/041 Primary

  of a solid body · CPC title

• G06N10/40 Primary

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

• G01R27/205

  Measuring contact resistance of connections, e.g. of earth connections · CPC title

• H01L39/08

  Electricity · mapped topic

• G06N10/00

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