Silicon Surface Modification Improves Qubit Performance
SQMS Scientists find changing standard acid treatment can improve qubit performance, and this result gives clues that point toward the sources of two-level systems losses.
The Science:
Replacing a Buffered Oxide Etch before Josephson Junction deposition with HF followed by ammonium fluoride changes the silicon surface and improves superconducting qubit performance by improving T1 and reducing the number of two-level systems coupled to the device.
The Impact:
This result utilized the expertise in fabrication and materials characterization across many SQMS member labs to demonstrate a systematic improvement that is compatible with existing processes.
Summary:
The team determined that a change in chemistry for a cleaning process can significantly improve the performance of qubits and reduce the number of two-level system defects that are detrimental to qubit devices. This change is easily incorporated into existing device process flows. In-depth analysis of the relevant surfaces and interfaces provides insights into what physical differences could contribute to the improvements.
Contact:
Cameron Kopas – ckopas@rigetti.com or Dominic Goronzy – dominic.goronzy@northwestern.edu
Focus Area:
Materials for 2D and 3D Quantum Devices
Institutions:
Rigetti Computing, Northwestern University, Ames National Laboratory, Fermi National Accelerator Laboratory
Citation:
C. J Kopas, D. P Goronzy, T. Pham, C. G Torres Castanedo, M. Cheng, R. Cochrane, P. Nast, E. Lachman, N. Z Zhelev, A. Vallières, A. A Murthy, J-S Oh, L. Zhou, M. J Kramer, H. Cansizoglu, M. J Bedzyk, V. P Dravid, A. Romanenko, A. Grassellino, J. Y Mutus, M. C Hersam and K. Yadavalli. “Enhanced superconducting qubit performance through ammonium fluoride etch.” (2024) Mater. Quantum. Technol. 4 045101.
Funding Acknowledgement:
This material is based upon work supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract no. DE-AC02-07CH11359. This work made use of the Rigetti Fab-1 facilities. This work made use of the EPIC and Keck-II facilities of the Northwestern University NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and the Northwestern MRSEC program (NSF DMR-2308691). This work also made use of the QSET facility of the Northwestern University Center for Applied Physics and Superconducting Technologies (CAPST), which has received support from SQMS. The Ames National Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358.