L. Origo

Transmon qubit modeling and characterization for Dark Matter search

  1. R. Moretti,
  2. D. Labranca,
  3. P. Campana,
  4. R. Carobene,
  5. M. Gobbo,
  6. M. A. Castellanos-Beltran,
  7. D. Olaya,
  8. P. F. Hopkins,
  9. L. Banchi,
  10. M. Borghesi,
  11. A. Candido,
  12. H. A. Corti,
  13. A. D'Elia,
  14. M. Faverzani,
  15. E. Ferri,
  16. A. Nucciotti,
  17. L. Origo,
  18. A. Pasquale,
  19. A. S. Piedjou Komnang,
  20. A. Rettaroli,
  21. S. Tocci,
  22. S. Carrazza,
  23. C. Gatti,
  24. and A. Giachero
This study presents the design, simulation, and experimental characterization of a superconducting transmon qubit circuit prototype for potential applications in dark matter detection
experiments. We describe a planar circuit design featuring two non-interacting transmon qubits, one with fixed frequency and the other flux tunable. Finite-element simulations were employed to extract key Hamiltonian parameters and optimize component geometries. The qubit was fabricated and then characterized at 20 mK, allowing for a comparison between simulated and measured qubit parameters. Good agreement was found for transition frequencies and anharmonicities (within 1\% and 10\% respectively) while coupling strengths exhibited larger discrepancies (30\%). We discuss potential causes for measured coherence times falling below expectations (T1∼1-2 \textmu s) and propose strategies for future design improvements. Notably, we demonstrate the application of a hybrid 3D-2D simulation approach for energy participation ratio evaluation, yielding a more accurate estimation of dielectric losses. This work represents an important first step in developing planar Quantum Non-Demolition (QND) single-photon counters for dark matter searches, particularly for axion and dark photon detection schemes.
arxiv pdf

Ultra low noise readout with travelling wave parametric amplifiers: the DARTWARS project

  1. A. Rettaroli,
  2. C. Barone,
  3. M. Borghesi,
  4. S. Capelli,
  5. G. Carapella,
  6. A. P. Caricato,
  7. I. Carusotto,
  8. A. Cian,
  9. D. Di Gioacchino,
  10. E. Enrico,
  11. P. Falferi,
  12. L. Fasolo,
  13. M. Faverzani,
  14. E. Ferri,
  15. G. Filatrella,
  16. C. Gatti,
  17. A. Giachero,
  18. D. Giubertoni,
  19. V. Granata,
  20. A. Greco,
  21. C. Guarcello,
  22. D. Labranca,
  23. A. Leo,
  24. C. Ligi,
  25. G. Maccarrone,
  26. F. Mantegazzini,
  27. B. Margesin,
  28. G. Maruccio,
  29. C. Mauro,
  30. R. Mezzena,
  31. A. G. Monteduro,
  32. A. Nucciotti,
  33. L. Oberto,
  34. L. Origo,
  35. S. Pagano,
  36. V. Pierro,
  37. L. Piersanti,
  38. M. Rajteri,
  39. S. Rizzato,
  40. A. Vinante,
  41. and M. Zannoni
The DARTWARS project has the goal of developing high-performing innovative travelling wave parametric amplifiers with high gain, large bandwidth, high saturation power, and nearly quantum-limited
noise. The target frequency region for its applications is 5 – 10 GHz, with an expected noise temperature of about 600 mK. The development follows two different approaches, one based on Josephson junctions and one based on kinetic inductance of superconductors. This contribution mainly focuses on the Josephson travelling wave parametric amplifier, presenting its design, preliminary measurements and the test of homogeneity of arrays of Josephson junctions.
arxiv pdf