Noise limits for dc SQUID readout of high-$Q$ resonators below 300 MHz
Abstract
We present the limits on noise for the readout of cryogenic high- resonators using dc Superconducting Quantum Interference Devices (SQUIDs) below 300 MHz. This analysis uses realized first-stage SQUIDs (previously published), whose performance is well described by Tesche-Clarke (TC) theory, coupled directly to the resonators. We also present data from a prototype second-stage dc SQUID array designed to couple to this first-stage SQUID as a follow-on amplifier with high system bandwidth. This analysis is the first full consideration of dc SQUID noise performance referred to a high- resonator over this frequency range, and is presented relative to the standard quantum limit. We include imprecision, backaction, and backaction-imprecision noise correlations from TC theory, the noise contributed by the second-stage SQUIDs, wiring, and preamplifiers, and optimizations for both on-resonance measurements and off-resonance scan sensitivity. This architecture has modern relevance due to the increased interest in axion searches and the requirements of the DMRadio-m axion search, which will use dc SQUIDs in this frequency range.
Cite
@article{arxiv.2504.20398,
title = {Noise limits for dc SQUID readout of high-$Q$ resonators below 300 MHz},
author = {V. Ankel and C. Bartram and J. Begin and C. Bell and L. Brouwer and S. Chaudhuri and John Clarke and H. -M. Cho and J. Corbin and W. Craddock and S. Cuadra and A. Droster and M. Durkin and J. Echevers and J. T. Fry and G. Hilton and K. D. Irwin and A. Keller and R. Kolevatov and A. Kunder and D. Li and N. Otto and K. M. W. Pappas and N. M. Rapidis and C. P. Salemi and D. Schmidt and M. Simanovskaia and J. Singh and P. Stark and C. D. Tesche and J. Ullom and L. Vale and E. C. van Assendelft and K. van Bibber and M. Vissers and K. Wells and J. Wiedemann and L. Winslow and D. Wright and A. K. Yi and B. A. Young},
journal= {arXiv preprint arXiv:2504.20398},
year = {2025}
}
Comments
17 pages, 4 figures