Spectral diffusion of nanomechanical resonators due to single quantum defects
Creators
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1.
Stanford University
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2.
California Institute of Technology
Abstract
Nanomechanical resonators promise diverse applications from mass spectrometry to quantum information processing, requiring long phonon lifetimes and frequency stability. Although two-level-system (TLS) defects govern dissipation at millikelvin temperatures, the nature of frequency fluctuations remains poorly understood. In nanoscale devices, where acoustic fields are confined to subwavelength volumes, strong coupling to individual TLSs should dominate over defect ensemble effects. In this work, we monitor fast spectral diffusion of phononic crystal nanomechanical resonators while varying the temperature (10 mK–1 K), drive power (10²–10⁵ phonons), and phononic band structure. We consistently observe random telegraph signals (RTSs), which we attribute to state transitions of individual TLSs. The spectral diffusion is well explained by mechanical coupling to individual far-off-resonant TLSs, which are either thermally excited or strongly coupled to thermal fluctuators. Understanding this fundamental decoherence process, particularly its RTS structure, opens a clear path toward noise suppression for quantum and sensing applications.
Copyright and License
© 2025 American Physical Society.
Acknowledgement
The authors would like to acknowledge numerous valuable discussions with Professor M.I. Dykman, K.K.S. Multani, A.Y. Cleland, T. Makihara, Y. Guo, and R.G. Gruenke for useful discussions and assistance during fabrication. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF) and at the Stanford Nanofabrication Facility (SNF), supported by the National Science Foundation under Award No. ECCS-2026822. Work was performed in part in the nano@stanford labs, which are supported by the National Science Foundation as part of the National Nanotechnology Coordinated Infrastructure initiative under Award No. ECCS-1542152. We gratefully acknowledge support from multiple sources that made this work possible. This material is based upon work supported by the Air Force Office of Scientific Research and the Office of Naval Research under Award No. FA9550-23-1-0338 (A.H.S.-N.). Additional funding was provided by Amazon Web Services, Inc. (A.H.S.-N.). We thank the Gordon and Betty Moore Foundation for support through Grant No. (M.L.R. and A.H.S.-N), a Moore Inventor Fellowship (A.H.S.-N.) and via the Wellcome Leap—Delta Tissue Program (M.L.R.), Award No. 2016555 (M.L.R.). This research was also supported by the National Science Foundation CAREER Award No. ECCS-1941826 (A.H.S.-N.). Some of this work was funded by the US Department of Energy through Grant No. DE-AC02-76SF00515 and via the Q-NEXT Center. M.P.M. gratefully acknowledges support from a Natural Sciences and Engineering Research Council of Canada (NSERC) fellowship.
Data Availability
The data that support the findings of this article are openly available [60]; embargo periods may apply.
Files
22rx-v855.pdf
Additional details
Related works
- Is supplemented by
- Dataset: 10.5281/zenodo.17095335 (DOI)
Funding
- National Science Foundation
- ECCS-2026822
- National Science Foundation
- ECCS-1542152
- United States Air Force Office of Scientific Research
- Office of Naval Research
- FA9550-23-1-0338
- Amazon (United States)
- Gordon and Betty Moore Foundation
- Moore Inventor Fellowship
- Wellcome Leap—Delta Tissue Program
- National Science Foundation
- ECCS-1941826
- United States Department of Energy
- DE-AC02-76SF00515
- Natural Sciences and Engineering Research Council
Dates
- Accepted
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2025-09-16
Caltech Custom Metadata
- Caltech groups
- Kavli Nanoscience Institute , Division of Engineering and Applied Science (EAS) , Division of Physics, Mathematics and Astronomy (PMA) , Physics Department
- Publication Status
- Published