Phase quantum bit

Patent metadata

Field	Value
Publication number	US-9780764-B2
Application number	US-75419410-A
Country	US
Kind code	B2
Filing date	Apr 5, 2010
Priority date	Apr 5, 2010
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A phase quantum bit is disclosed. In one embodiment, the phase quantum bit may comprise a Josephson junction and a distributed element coupled to the Josephson junction. The distributed element provides a capacitive component and an inductive component of the phase quantum bit.

First claim

What is claimed is:

1. A phase quantum bit comprising:
a Josephson junction;
a distributed element coupled to the Josephson junction, the distributed element providing a capacitive component and an inductive component of the phase quantum bit; and
a control circuit coupled to the distributed element for biasing the phase quantum bit and a readout circuit coupled to the distributed element for reading the phase quantum bit, wherein the control circuit and/or the readout circuit are coupled to the distributed element at a location where the magnitude of the radio frequency (RF) current is approximately zero.

2. The phase quantum bit of claim 1 , wherein the distributed element is a transmission line.

3. The phase quantum bit of claim 2 , wherein the transmission line is one of a coplanar waveguide, a slot line waveguide, a stripline waveguide and a microstrip waveguide.

4. The phase quantum bit of claim 1 , further comprising a shunting impedance coupled to a second end of the distributed element with a first end of the distributed element being coupled to the Josephson junction.

5. The phase quantum bit of claim 4 , wherein the shunting impedance is a short.

6. The phase quantum bit of claim 4 , wherein the shunting impedance is an open.

7. The phase quantum bit of claim 4 , wherein the shunting impedance is at least one of a capacitor, an inductor, a transmission line and a second Josephson junction.

8. A quantum circuit comprising:
a phase quantum bit comprising:
a Josephson junction;
a transmission line coupled to the Josephson junction, the transmission line providing a capacitive component and an inductive component of the phase quantum bit; and
a shunt impedance coupled to a second end of the transmission line with a first end of the transmission line being coupled to the Josephson junction; and

a control circuit coupled to the transmission line for biasing the phase quantum bit; and
a readout circuit coupled to the transmission line for reading the phase quantum bit
wherein the control circuit and the readout circuit are coupled to the transmission line at a location where the magnitude of the radio frequency (RF) current is approximately zero.

9. The quantum circuit of claim 8 , wherein the transmission line is one of a coplanar waveguide, a slot line waveguide, a stripline waveguide and a microstrip waveguide.

10. The quantum circuit of claim 8 , wherein the shunting impedance is a short at the second end of the transmission line.

11. The quantum circuit of claim 8 , wherein the shunting impedance is an open at the first end of the transmission line.

12. The quantum circuit of claim 8 , wherein the shunting impedance is at least one of a capacitor, an inductor, a transmission line and a second Josephson junction.

13. A method of forming a phase quantum bit, the method comprising:
forming a Josephson junction;
forming a distributed element that provides a capacitive component and an inductive component of the phase quantum bit;
coupling a first end of the distributed element to the Josephson junction;
forming a control circuit coupled to the distributed element adjacent a first location for biasing the phase quantum bit; and
forming a readout circuit coupled to the distributed element adjacent the first location for reading the phase quantum bit, wherein the first location is at a location where the magnitude of the radio frequency (RF) current of the phase quantum bit is approximately zero.

14. The method of claim 13 , wherein the forming a distributed element comprises forming a second end of the distributed element that is shorted.

15. The method of claim 13 , further comprising forming a shunting impedance coupled to a second end of the distributed element, wherein the shunting impedance is at least one of an open circuit, a capacitor, an inductor, a transmission line and a second Josephson junction.

16. The method of claim 13 , further comprising forming an intermediate layer between the Josephson junction and the distributed element and forming a contact through the intermediate layer to couple the Josephson junction to the distributed element.

Assignees

• Pesetski Aaron A
• Baumgardner James E
• Lewis Rupert M
• Northrop Grumman Systems Corp

Inventors

• Pesetski Aaron A
• Baumgardner James E
• Lewis Rupert M

Classifications

• Y10T29/49014

  Superconductor · CPC title

• H03K3/38 Primary

  by the use, as active elements, of superconductive devices · CPC title

• H01L39/2493

  Electricity · mapped topic

• H01L39/223

  Electricity · mapped topic

• H10N60/0912

  of Josephson-effect devices · CPC title