Jacques Van Damme

CryoCMOS RF multiplexer for superconducting qubit control, readout and flux biasing at millikelvin temperatures with picowatt power consumption

  1. Liam Fallik,
  2. Sriram Balamurali,
  3. Alican Caglar,
  4. Rohith Acharya,
  5. Jacques Van Damme,
  6. Tsvetan Ivanov,
  7. Shana Massar,
  8. Ruben Asanovski,
  9. A. M. Vadiraj,
  10. Massimo Mongillo,
  11. Jan Craninckx,
  12. Alexander Grill,
  13. Danny Wan,
  14. Anton Potočnik,
  15. and Kristiaan De Greve
Large-scale cryogenic quantum systems are constrained by an input-output bottleneck between room-temperature electronics and millikelvin stages, particularly in superconducting qubit
platforms. This bottleneck is most acute for output lines, where bulky and expensive microwave components limit scalability. A promising approach for scalable characterization and testing is to perform signal multiplexing directly at the qubit plane. We demonstrate a cryogenic CMOS (cryoCMOS) RF multiplexer operating at 10 millikelvin with record-low static power consumption of 200 pW. The device provides < 2 dB insertion loss and > 30 dB isolation across DC-8 GHz. Direct connection to transmon qubits marginally affects coherence times in the range of 100 microseconds, enabling multiplexing of readout, flux and, in principle, XY drive lines. This work introduces cryoCMOS multiplexers as valuable tools for scalable, high-throughput cryogenic characterization and testing, and advances co-integrated quantum-classical control for future large-scale quantum processors.
arxiv pdf

High-coherence superconducting qubits made using industry-standard, advanced semiconductor manufacturing

  1. Jacques Van Damme,
  2. Shana Massar,
  3. Rohith Acharya,
  4. Tsvetan Ivanov,
  5. Daniel Perez Lozano,
  6. Yann Canvel,
  7. Mael Demarets,
  8. Diziana Vangoidsenhoven,
  9. Yannick Hermans,
  10. Ju-Geng Lai,
  11. Vadiraj Rao,
  12. Massimo Mongillo,
  13. Danny Wan,
  14. Jo De Boeck,
  15. Anton Potocnik,
  16. and Kristiaan De Greve
The development of superconducting qubit technology has shown great potential for the construction of practical quantum computers. As the complexity of quantum processors continues
to grow, the need for stringent fabrication tolerances becomes increasingly critical. Utilizing advanced industrial fabrication processes could facilitate the necessary level of fabrication control to support the continued scaling of quantum processors. However, these industrial processes are currently not optimized to produce high coherence devices, nor are they a priori compatible with the commonly used approaches to make superconducting qubits. In this work, we demonstrate for the first time superconducting transmon qubits manufactured in a 300 mm CMOS pilot line, using industrial fabrication methods, with resulting relaxation and coherence times already exceeding 100 microseconds. We show across-wafer, large-scale statistics studies of coherence, yield, variability, and aging that confirm the validity of our approach. The presented industry-scale fabrication process, using exclusively optical lithography and reactive ion etching, shows performance and yield similar to the conventional laboratory-style techniques utilizing metal lift-off, angled evaporation, and electron-beam writing. Moreover, it offers potential for further upscaling by including three-dimensional integration and additional process optimization using advanced metrology and judicious choice of processing parameters and splits. This result marks the advent of more reliable, large-scale, truly CMOS-compatible fabrication of superconducting quantum computing processors.
arxiv pdf