Y. Li

Ultra-high Q-factor superconducting tantalum resonators on 300 mm Si wafers

  1. R. Acharya,
  2. D. Perez Lozano,
  3. Ts. Ivanov,
  4. S. Massar,
  5. C. Vrancken,
  6. Y. Canvel,
  7. Y. Li,
  8. A. M. Vadiraj,
  9. J. Van Damme,
  10. S. Aghaeimeibodi,
  11. A. Khalajhedayati,
  12. M. Mongillo,
  13. O. Painter,
  14. D. Wan,
  15. A. Potočnik,
  16. and K. De Greve
Superconducting resonators are central to superconducting quantum information technologies and essential for bosonic qubit architectures, where long-lived storage modes enable hardware-efficient
error correction. Achieving ultra-high quality factors in scalable planar circuits is challenging because multiple dissipation channels contribute to the total loss. Here we report planar α-Ta resonators fabricated on 300 mm ultra-high-resistivity (>10 kΩ cm) intrinsic silicon using industrial processes, achieving median internal Q factors exceeding 40 million and maxima above 60 million. Energy-participation-ratio analysis identifies a dominant participation-controlled interface loss mechanism and places conservative upper bounds on substrate-associated dissipation. For the best-performing substrate, the inferred substrate loss tangent is below 1.0×10−8, establishing industrial MCZ silicon among the lowest-loss substrate platforms reported for superconducting resonators. At the same time, the exceptionally low losses show no clear correlation with commonly cited silicon substrate metrics such as room-temperature resistivity or impurity concentrations. More broadly, these studies establish industrial 300 mm processing, careful interface engineering, and 300 mm MCZ silicon substrates as a promising platform for resonator-heavy superconducting quantum architectures with ultra-high quality factors.
arxiv pdf

Verifying quantum information scrambling dynamics in a fully controllable superconducting quantum simulator

  1. J.-H. Wang,
  2. T.-Q. Cai,
  3. X.-Y. Han,
  4. Y.-W Ma,
  5. Z. L. Wang,
  6. Z.-H Bao,
  7. Y. Li,
  8. H.-Y Wang,
  9. H.-Y Zhang,
  10. L.-Y Sun,
  11. Y.-K. Wu,
  12. Y. P. Song,
  13. and L. M. Duan
Quantum simulation elucidates properties of quantum many-body systems by mapping its Hamiltonian to a better-controlled system. Being less stringent than a universal quantum computer,
noisy small- and intermediate-scale quantum simulators have successfully demonstrated qualitative behavior such as phase transition, localization and thermalization which are insensitive to imperfections in the engineered Hamiltonian. For more complicated features like quantum information scrambling, higher controllability will be desired to simulate both the forward and the backward time evolutions and to diagnose experimental errors, which has only been achieved for discrete gates. Here, we study the verified scrambling in a 1D spin chain by an analogue superconducting quantum simulator with the signs and values of individual driving and coupling terms fully controllable. We measure the temporal and spatial patterns of out-of-time ordered correlators (OTOC) by engineering opposite Hamiltonians on two subsystems, with the Hamiltonian mismatch and the decoherence extracted quantitatively from the scrambling dynamics. Our work demonstrates the superconducting system as a powerful quantum simulator.
arxiv pdf