O. Painter

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

Mechanical On-Chip Microwave Circulator

  1. S. Barzanjeh,
  2. M. Wulf,
  3. M. Peruzzo,
  4. M. Kalaee,
  5. P. B. Dieterle,
  6. O. Painter,
  7. and J. M. Fink
Nonreciprocal circuit elements form an integral part of modern measurement and communication systems. Mathematically they require breaking of time-reversal symmetry, typically achieved
using magnetic materials and more recently using the quantum Hall effect, parametric permittivity modulation or Josephson nonlinearities. Here, we demonstrate an on-chip magnetic-free circulator based on reservoir engineered optomechanical interactions. Directional circulation is achieved with controlled phase-sensitive interference of six distinct electro-mechanical signal conversion paths. The presented circulator is compact, its silicon-on-insulator platform is compatible with both superconducting qubits and silicon photonics, and its noise performance is close to the quantum limit. With a high dynamic range, a tunable bandwidth of up to 30 MHz and an in-situ reconfigurability as beam splitter or wavelength converter, it could pave the way for superconducting qubit processors with integrated and multiplexed on-chip signal processing and readout.
arxiv pdf