Driving the common-mode of a Josephson parametric converter using a short-circuited coplanar stripline
View Patent ↗Techniques relate to an on-chip Josephson parametric converter. A Josephson ring modulator includes four nodes. A lossless on-chip flux line is capacitively coupled to two adjacent nodes of the four nodes of the Josephson ring modulator. The lossless on-chip flux line has an input port configured to receive a pump drive signal that couples differentially to the two adjacent nodes of the of the Josephson ring modulator. The pump drive signal thereby excites a common mode of the on-chip Josephson parametric converter.
1. An on-chip Josephson parametric converter, comprising:
a Josephson ring modulator;
one or more transmission lines coupled to the Josephson ring modulator, the one or more transmission lines configured to feed the Josephson ring modulator; and
a flux line capacitively coupled to the Josephson ring modulator, the flux line being separate from and not galvanically connected to the one or more transmission lines.
2. The on-chip Josephson parametric converter of claim 1 , wherein the flux line comprises an input port configured to receive a pump drive signal that couples differentially to two adjacent nodes of the Josephson ring modulator, the pump drive signal thereby exciting a common mode of the Josephson parametric converter.
3. The on-chip Josephson parametric converter of claim 2 , wherein the Josephson ring modulator comprises four nodes which include the two adjacent nodes.
4. The on-chip Josephson parametric converter of claim 2 , wherein the flux line is configured to transmit a high frequency microwave signal as the pump drive signal to the two adjacent nodes of the Josephson ring modulator, the high frequency microwave signal being transmitted via a first capacitor and a second capacitor of first and second nodes of the two adjacent nodes.
5. The on-chip Josephson parametric converter of claim 4 , wherein the high frequency microwave signal ranges from 3-20 gigahertz.
6. The on-chip Josephson parametric converter of claim 1 , wherein the flux line is a lossless on-chip flux line.
7. The on-chip Josephson parametric converter of claim 1 , wherein the flux line is a short-circuited coplanar stripline.
8. The on-chip Josephson parametric converter of claim 7 , wherein the Josephson ring modulator comprises four nodes; and
wherein the short-circuited coplanar stripline couples to the Josephson ring modulator via a first capacitance at a first node of the four nodes and couples to the Josephson ring modulator via a second capacitance at a second node of the four nodes.
9. The on-chip Josephson parametric converter of claim 8 , wherein the first capacitance and the second capacitance are based on a proximity of the short-circuited coplanar stripline to the first and second nodes.
10. The on-chip Josephson parametric converter of claim 1 , further comprising a first resonator and a second resonator that intersect at the Josephson ring modulator and respectively enable a first and a second differential mode of the on-chip Josephson parametric converter;
wherein the one or more transmission lines comprise the first and second resonators.
11. The on-chip Josephson parametric converter of claim 10 , wherein the first resonator, the second resonator, and the flux line each have a separate input port.
12. The on-chip Josephson parametric converter of claim 10 , wherein the first resonator, the second resonator, the flux line, and the Josephson ring modulator are each formed of superconducting material.
13. The on-chip Josephson parametric converter of claim 1 , wherein the Josephson ring modulator comprises a plurality of inductors having one end shunted and another end respectively connected to four nodes of the Josephson ring modulator.
14. A method of forming an on-chip Josephson parametric converter, the method comprising:
forming a Josephson ring modulator;
coupling one or more transmission lines to the Josephson ring modulator, the one or more transmission lines configured to feed the Josephson ring modulator; and
coupling a flux line capacitively to the Josephson ring modulator, the flux line being separate from and not galvanically connected to the one or more transmission lines.
15. The method of claim 14 , wherein the flux line comprises an input port configured to receive a pump drive signal that couples differentially to two adjacent nodes of the Josephson ring modulator, the pump drive signal thereby exciting a common mode of the Josephson parametric converter.
16. The method of claim 15 , wherein the Josephson ring modulator comprises four nodes which include the two adjacent nodes.
17. The method of claim 14 , wherein the flux line is a lossless on-chip flux line.
18. The method of claim 14 , wherein the flux line is a short-circuited coplanar stripline.
19. The method of claim 18 , wherein the Josephson ring modulator comprises four nodes; and
wherein the short-circuited coplanar stripline couples to the Josephson ring modulator via a first capacitance at a first node of the four nodes and couples to the Josephson ring modulator via a second capacitance at a second node of the four nodes.
20. A method of providing a pump drive to an on-chip Josephson parametric converter, the method comprising:
providing a flux line in proximity to a Josephson ring modulator of the on-chip Josephson parametric converter such that the flux line couples capacitively to the Josephson ring modulator; and
transmitting a microwave signal as the pump drive to the on-chip Josephson parametric converter using the flux line.