# US 9,437,800 B1 · Systems and methods for suppressing magnetically active surface defects in superconducting circuits

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,437,800 B1
- Document ID: US9437800B1
- Status: Granted
- Kind: B1
- Application number: 14/632,505
- Filed: 2015-02-26
- Published: 2016-09-01
- Granted: 2016-09-06
- Earliest claimed: 2015-02-26
- Assignees: Wisconsin Alumni Research Foundation
- Applicants: Robert Francis McDermott, III; Pradeep Kumar
- Inventors: Robert Francis McDermott, III; Pradeep Kumar
- Web page: https://patentgrep.com/patent/US9437800B1

## CPC

- H10N 60/815: {for Josephson-effect devices}
- H10N 60/0912: {of Josephson-effect devices}
- H10N 69/00: Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Systems and methods for suppressing magnetically active surface defects in superconducting quantum circuits are provided. A method includes providing one or more superconducting quantum circuits, and arranging the one or more superconducting quantum circuits in a hermetic enclosure capable of isolating the one or more superconducting circuits from ambient surroundings. The method also includes controlling an environment in the hermetic enclosure to suppress magnetically active surface defects associated with the one or more superconducting quantum circuits. In some aspects, the method further includes introducing an inert gas into the hermetic enclosure to passivate a surface of the one or more superconducting quantum circuits. In other aspects, the method further includes coating a surface of the one or more superconducting circuits with a non-magnetic encapsulation layer. In yet other aspects, the method further includes irradiating the one or more superconducting circuits using ultraviolet light.

## Claims

### Claim 1

A method for reducing magnetic noise in qubit circuits, the method comprising:
providing one or more qubit circuits;
arranging the one or more qubit circuits in a hermetic enclosure capable of isolating the one or more qubit circuits from ambient surroundings; and
controlling a background pressure of one or more magnetically active species in the hermetic enclosure to suppress magnetic active surface defects associated with the one or more qubit circuits.

### Claim 2 (depends on 1)

The method of claim 1, wherein the one or more magnetically active species comprises oxygen.

### Claim 3 (depends on 1)

The method of claim 1, the method further comprising elevating a temperature of the hermetic enclosure.

### Claim 4 (depends on 1)

The method of claim 1, the method further comprising irradiating the one or more qubit circuits using ultraviolet light.

### Claim 5 (depends on 1)

The method of claim 1, the method further comprising passivating a surface of the one or more qubit circuits.

### Claim 6 (depends on 1)

The method of claim 1, the method further comprising coating a surface of the one or more qubit circuits with a non-magnetic encapsulation layer.

### Claim 7 (depends on 1)

The method of claim 1, the method further comprising introducing an inert gas into the hermetic enclosure.

### Claim 8 (depends on 7)

The method of claim 7, wherein the inert gas includes an ammonia gas.

### Claim 9 (depends on 1)

The method of claim 1, wherein the background pressure is less than about 1·10−6 Torr.

### Claim 10

A system for suppressing magnetically active surface defects in superconducting quantum circuits, the system comprising:
a hermetic enclosure configured to accommodate therein one or more superconducting quantum circuits, and capable of isolating the one or more superconducting circuits from ambient surroundings; and
a vacuum system removably coupled to the hermetic enclosure, and configured to control an environment in the hermetic enclosure such that magnetic active surface defects associated with the one or more superconducting quantum circuits are suppressed.

### Claim 11 (depends on 10)

The system of claim 10, wherein the one or more superconducting quantum circuits includes at least one qubit circuit.

### Claim 12 (depends on 10)

The system of claim 10, wherein the vacuum system is further configured to control a background pressure of one or more magnetically active species in the hermetic enclosure.

### Claim 13 (depends on 12)

The system of claim 12, wherein the background pressure is less than about 1·10−6 Torr.

### Claim 14 (depends on 12)

The system of claim 12, wherein the magnetically active species comprises oxygen.

### Claim 15 (depends on 10)

The system of claim 10, wherein the vacuum system is further configured to introduce an inert gas in the hermetic enclosure to passivate a surface of the one or more superconducting quantum circuits.

### Claim 16 (depends on 15)

The system of claim 15, wherein the inert gas includes an ammonia gas.

### Claim 17 (depends on 10)

The system of claim 10, the hermetic enclosure further comprising a light source capable of irradiating the one or more superconducting circuits using ultraviolet light.

### Claim 18 (depends on 10)

The system of claim 10, the system further comprising a heat source for elevating a temperature of the hermetic enclosure.

### Claim 19

A method for suppressing magnetically active surface defects in superconducting quantum circuits, the method comprising:
providing one or more superconducting quantum circuits;
arranging the one or more superconducting quantum circuits in a hermetic enclosure; and
controlling an environment in the hermetic enclosure to suppress magnetic active surface defects associated with the one or more superconducting quantum circuits.

### Claim 20 (depends on 19)

The method of claim 19, wherein the one or more superconducting quantum circuits includes at least one qubit circuit.

### Claim 21 (depends on 19)

The method of claim 19, wherein controlling the environment includes reducing a background pressure of one or more magnetically active species in the hermetic enclosure using a vacuum system coupled to the hermetic enclosure.

### Claim 22 (depends on 21)

The method of claim 21, wherein the magnetically active species comprises oxygen.

### Claim 23 (depends on 19)

The method of claim 19, the method further comprising elevating a temperature of the hermetic enclosure.

### Claim 24 (depends on 19)

The method of claim 19, the method further comprising irradiating the one or more superconducting circuits using ultraviolet light.

### Claim 25 (depends on 19)

The method of claim 19, the method further comprising passivating a surface of the one or more superconducting quantum circuits.

### Claim 26 (depends on 19)

The method of claim 19, the method further comprising coating a surface of the one or more superconducting quantum circuits with a non-magnetic encapsulation layer.

### Claim 27 (depends on 19)

The method of claim 19, the method further comprising introducing an inert gas into the hermetic enclosure to passivate a surface of the one or more superconducting quantum circuits.

### Claim 28 (depends on 27)

The method of claim 27, wherein the inert gas includes an ammonia gas.