Integrating circuit elements in a stacked quantum computing device

1. A device comprising:

a first chip comprising a superconducting qubit, the superconducting qubit comprising a superconducting quantum interference device (SQUID) region, a control region and a readout region; and

a second chip bonded to the first chip, the second chip comprising a first control element directly overlapping the SQUID region, a second control element displaced laterally from and without overlapping the control region, and a readout device directly overlapping the readout region.

2. The device of claim 1 , wherein the readout device comprises a resonator element electrically coupled to a pad element, wherein the pad element overlaps the readout region without the resonator element overlapping the readout region.

3. The device of claim 2 , wherein the pad element is symmetrically aligned with the readout region of the superconducting qubit.

4. The device of claim 3 , wherein the readout region comprises a portion of the superconducting qubit, and a surface area of the portion of the superconducting qubit within the readout region that is facing the second chip is less than a surface area of the pad element facing the first chip.

5. The device of claim 2 , wherein the pad element is operable to capacitively couple to a portion of the superconducting qubit within the readout region.

6. The device of claim 1 , wherein the first chip comprises a superconductor ground plane having an edge aligned with the control region of the superconducting qubit, wherein the edge comprises a recessed region, and wherein the second control element is aligned over the recessed region.

7. The device of claim 6 , wherein a total surface area of the second control element facing the first chip is less than a total surface area of the recessed region facing the second chip.

8. The device of claim 6 , wherein the second control element is operable to capacitively couple to the control region.

9. The device of claim 1 , wherein the second control element is operable to excite the superconducting qubit.

10. The device of claim 1 , wherein the first control element comprises a bias coil, the bias coil comprising a layer of superconductor material arranged in a loop, and wherein the SQUID region comprises a SQUID arranged in a ring.

11. The device of claim 10 , wherein the loop comprises an inner loop edge and an outer loop edge, and wherein the inner loop edge is aligned within an inner area of the ring, and the outer loop edge is aligned outside of the inner area of the ring.

12. The device of claim 11 , wherein a lateral distance between the inner loop edge and an edge of the ring defining the inner area of the ring is at least 2 microns, and wherein a lateral distance between the outer loop edge and the edge of the ring defining the inner area of the ring is at least approximately 2 microns.

13. The device of claim 10 , wherein the loop comprises an inner loop edge and an outer loop edge, and wherein the outer loop edge is aligned within an inner area of the ring.

14. The device of claim 13 , wherein a lateral distance between the outer loop edge and an edge of the ring defining the inner area of the ring 1 s at least approximately 2 microns.

15. The device of claim 1 , wherein the first control element is operable to tune the superconducting qubit.

16. The device of claim 1 , wherein the first control element is operable to inductively couple to the SQUID region.

17. The device of claim 1 , wherein the first chip is bump bonded to the second chip.

18. The device of claim 1 , further comprising a gap between the first chip and the second chip, wherein a height of the gap between the first chip and the second chip is between about 1 micron and about 10 microns.

19. The device of claim 1 , wherein the first control element, the second control element, and the readout device comprise superconductor material.

20. The device of claim 1 , wherein the superconducting qubit is a transmon qubit, flux qubit, or gmon qubit.