Incorporating arrays of Josephson junctions in a Josephson junction ring modulator in a Josephson parametric converter

1. A Josephson parametric converter, comprising:

a multi-Josephson junction ring modulator having arrays of N Josephson junctions arranged in a ring configuration with ring nodes inter-dispersed between the arrays, and further having a center node inter-connecting the ring nodes, wherein N is an integer having a value greater than one; and

a first and a second resonator formed from lumped-element capacitors that shunt the multi-Josephson junction ring modulator and respectively enable a first and a second mode of the Josephson parametric converter.

2. The Josephson parametric converter of claim 1 , wherein a center frequency of the Josephson parametric converter is tunable by varying a magnetic flux threading the ring configuration.

3. The Josephson parametric converter of claim 1 , wherein a center frequency of the Josephson parametric converter is tunable by shunting each of the arrays of the multi-Josephson junction parametric converter by a linear shunt inductance.

4. The Josephson parametric converter of claim 3 , wherein the linear shunt inductance is implemented by superconducting wires.

5. The Josephson parametric converter of claim 3 , wherein the linear shunt inductance is implemented by additional arrays of Josephson junctions, each arranged between the center node and a respective one of the ring nodes.

6. The Josephson parametric converter of claim 5 , wherein the linear shunt inductance is proportional to a number of Josephson junctions in each of the additional arrays and a Josephson inductance of each of the Josephson junctions in each of the additional arrays.

7. The Josephson parametric converter of claim 1 , wherein the N Josephson junctions in each of the arrays are connected in series.

8. The Josephson parametric converter of claim 1 , wherein the first resonator comprises at least one capacitor shunted across a first ring node a third ring node from among the ring nodes, and the second resonator comprises at least one other capacitor shunted across a second ring node and a fourth ring node from among the ring nodes.

9. The Josephson parametric converter of claim 8 , wherein multi-Josephson junction ring modulator has two opposing pairs of ring nodes, a first of the two opposing pairs of ring nodes formed from the first ring node and the third ring node, and a second of the two opposing pairs of nodes formed from the second ring node and the fourth ring node.

10. The Josephson parametric converter of claim 1 , further comprising a first, a second, a third, and a fourth coupling capacitor, each having a first electrode connected to a respective different one of the ring nodes of the multi-Josephson junction ring modulator, and having a second electrode for connecting to a respective one of a plurality of feedlines.

11. A method, comprising:

forming a Josephson parametric converter, wherein said forming step includes:

forming a multi-Josephson junction ring modulator having arrays of N Josephson junctions arranged in a ring configuration with ring nodes inter-dispersed between the arrays, and further having a center node inter-connecting the ring nodes, wherein N is an integer having a value greater than one; and

forming a first and a second resonator from lumped-element capacitors that shunt the multi-Josephson junction ring modulator and respectively enable a first and a second mode of the Josephson parametric converter.

12. The method of claim 11 , wherein a center frequency of the Josephson parametric converter is tunable by varying a magnetic flux threading the ring configuration.

13. The method of claim 11 , wherein a center frequency of the Josephson parametric converter is tunable by shunting each of the arrays of the multi-Josephson junction parametric converter by a linear shunt inductance.

14. The method of claim 13 , wherein the linear shunt inductance is implemented by superconducting wires.

15. The method of claim 13 , wherein the linear shunt inductance is implemented by additional arrays of Josephson junctions, each arranged between the center node and a respective one of the ring nodes.

16. The method of claim 15 , wherein the linear shunt inductance is proportional to a number of Josephson junctions in each of the additional arrays and a Josephson inductance of each of the Josephson junctions in each of the additional arrays.

17. The method of claim 11 , wherein the N Josephson junctions in each of the arrays are connected in series.

18. The method of claim 11 , wherein forming the first and the second resonator comprise:

shunting at least one capacitor across a first ring node and a third ring node from among the ring nodes; and

shunting at least one other capacitor across a second ring node and a fourth ring node from among the ring nodes.

19. The method of claim 18 , wherein multi-Josephson junction ring modulator is formed to have two opposing pairs of nodes, a first of the two opposing pairs of nodes formed from the first ring node and the third ring node, and a second of the two opposing pairs of nodes formed from the second node and the fourth node.

20. The method of claim 11 , further comprising forming a first, a second, a third, and a fourth coupling capacitor, each having a first electrode connected to a respective different one of the ring nodes of the multi-Josephson junction ring modulator, and having a second electrode for connecting to a respective one of a plurality of feedlines.