Parametrically-Activated Entangling Gates Using Transmon Qubits

  1. S. Caldwell,
  2. N. Didier,
  3. C. A. Ryan,
  4. E. A. Sete,
  5. A. Hudson,
  6. P. Karalekas,
  7. R. Manenti,
  8. M. Reagor,
  9. M. P. da Silva,
  10. R. Sinclair,
  11. E. Acala,
  12. N. Alidoust,
  13. J. Angeles,
  14. A. Bestwick,
  15. M. Block,
  16. B. Bloom,
  17. A. Bradley,
  18. C. Bui,
  19. L. Capelluto,
  20. R. Chilcott,
  21. J. Cordova,
  22. G. Crossman,
  23. M. Curtis,
  24. S. Deshpande,
  25. T. El Bouayadi,
  26. D. Girshovich,
  27. S. Hong,
  28. K. Kuang,
  29. M. Lenihan,
  30. T. Manning,
  31. J. Marshall,
  32. Y. Mohan,
  33. W. O'Brien,
  34. C. Osborn,
  35. J. Otterbach,
  36. A. Papageorge,
  37. J.-P. Paquette,
  38. M. Pelstring,
  39. A. Polloreno,
  40. G. Prawiroatmodjo,
  41. V. Rawat,
  42. R. Renzas,
  43. N. Rubin,
  44. D. Russell,
  45. M. Rust,
  46. D. Scarabelli,
  47. M. Scheer,
  48. M. Selvanayagam,
  49. R. Smith,
  50. A. Staley,
  51. M. Suska,
  52. N. Tezak,
  53. T.-W. To,
  54. M. Vahidpour,
  55. N. Vodrahalli,
  56. T. Whyland,
  57. K. Yadav,
  58. W. Zeng,
  59. and C. Rigetti
We propose and implement a family of entangling qubit operations activated by radio-frequency flux pulses. By parametrically modulating the frequency of a tunable transmon, these operations selectively actuate resonant exchange of excitations with a statically coupled, but otherwise off-resonant, neighboring transmon. This direct exchange of excitations between qubits obviates the need for mediator qubits or resonator modes, and it allows for the full utilization of all qubits in a scalable architecture. Moreover, we are able to activate three highly-selective resonances, corresponding to two different classes of entangling gates that enable universal quantum computation: an iSWAP and a controlled-Z rotation. This selectivity is enabled by resonance conditions that depend both on frequency and amplitude, and is helpful in avoiding frequency crowding in a scalable architecture. We report average process fidelities of F = 0.93 for a 135 ns iSWAP, and F = 0.92 for 175 ns and 270 ns controlled-Z operations.
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