A. Giachero

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

Kinetic inductance traveling wave amplifier designs for practical microwave readout applications

  1. A. Giachero,
  2. M. Visser,
  3. J. Wheeler,
  4. L. Howe,
  5. J. Gao,
  6. J. Austermann,
  7. J. Hubmayr,
  8. A. Nucciotti3,
  9. and J. Ullom
A Kinetic Inductance Traveling Wave amplifier (KIT) utilizes the nonlinear kinetic inductance of superconducting films, particularly Niobium Titanium Nitride (NbTiN), for parametric
amplification. These amplifiers achieve remarkable performance in terms of gain, bandwidth, compression power, and frequently approach the quantum limit for noise. However, most KIT demonstrations have been isolated from practical device readout systems. Using a KIT as the first amplifier in the readout chain of an unoptimized microwave SQUID multiplexer coupled to a transition-edge sensor microcalorimeter we see an initial improvement in the flux noise. One challenge in KIT integration is the considerable microwave pump power required to drive the non-linearity. To address this, we have initiated efforts to reduce the pump power by using thinner NbTiN films and an inverted microstrip transmission line design. In this article, we present the new transmission line design, fabrication procedure, and initial device characterization — including gain and added noise. These devices exhibit over 10 dB of gain with a 3 dB bandwidth of approximately 5.5-7.25 GHz, a maximum practical gain of 12 dB and typical gain ripple under 4 dB peak-to-peak. We observe an appreciable impedance mismatch in the NbTiN transmission line, which is likely the source of the majority of the gain ripple. Finally we perform an initial noise characterization and demonstrate system-added noise of three quanta or less over nearly the entire 3 dB bandwidth.
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

Bimodal Approach for Noise Figures of Merit Evaluation in Quantum-Limited Josephson Traveling Wave Parametric Amplifiers

  1. L. Fasolo,
  2. C. Barone,
  3. M. Borghesi,
  4. G. Carapella,
  5. A. P. Caricato,
  6. I. Carusotto,
  7. W. Chung,
  8. A. Cian,
  9. D. Di Gioacchino,
  10. E. Enrico,
  11. P. Falferi,
  12. M. Faverzani,
  13. E. Ferri,
  14. G. Filatrella,
  15. C. Gatti,
  16. A. Giachero,
  17. D. Giubertoni,
  18. A. Greco,
  19. C. Kutlu,
  20. A. Leo,
  21. C. Ligi,
  22. P. Livreri,
  23. G. Maccarrone,
  24. B. Margesin,
  25. G. Maruccio,
  26. A. Matlashov,
  27. C. Mauro,
  28. R. Mezzena,
  29. A. G. Monteduro,
  30. A. Nucciotti,
  31. L. Oberto,
  32. S. Pagano,
  33. V. Pierro,
  34. L. Piersanti,
  35. M. Rajteri,
  36. A. Rettaroli,
  37. S. Rizzato,
  38. Y. K. Semertzidis,
  39. U. Uchaikin,
  40. and A. Vinante
The advent of ultra-low noise microwave amplifiers revolutionized several research fields demanding quantum-limited technologies. Exploiting a theoretical bimodal description of a linear
phase-preserving amplifier, in this contribution we analyze some of the intrinsic properties of a model architecture (i.e., an rf-SQUID based Josephson Traveling Wave Parametric Amplifier) in terms of amplification and noise generation for key case study input states (Fock and coherents). Furthermore, we present an analysis of the output signals generated by the parametric amplification mechanism when thermal noise fluctuations feed the device.
arxiv pdf