ORCID Profile
0000-0003-1481-1966
Current Organisation
University of Colorado at Boulder
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Publisher: Springer Science and Business Media LLC
Date: 12-2021
Publisher: AIP Publishing
Date: 11-2018
DOI: 10.1063/1.5055887
Abstract: We implement a non-contact, external method of simultaneously fine-tuning a mechanical resonator and a superconducting radio frequency (SRF) cavity using a capacitor formed between a silicon nitride membrane and a copper electrode at cryogenic temperatures. The silicon nitride membrane forms a variable boundary condition for the SRF cavity thereby creating the optomechanical cavity. By controlling the DC voltage applied between an external electrode and the silicon nitride membrane we are capable of tuning the resonance frequency internal to the SRF cavity up to 25 kHz for a cavity with loaded quality factor of 2.5 million, corresponding to six cavity linewidths. At the same time we observe the electrostatic frequency shift of the membrane. This approach has the unique benefit of avoiding any dielectric insertion or added gaps due to a moving end-wall thereby limiting the loss of the cavity. Furthermore, this design avoids applied pressure typically used with piezoelectric devices in accelerator cavities. This work seeks to have strong impact in tuning high-Q cavities due to its ability to maintain low losses.
Publisher: Springer Science and Business Media LLC
Date: 03-08-2020
Publisher: AIP Publishing
Date: 05-11-2019
DOI: 10.1063/1.5110611
Abstract: Three-dimensional radio frequency cavities demonstrate excellent frequency selectivity and, as such, are known for their use in RF filters. These cavities have potential applications in quantum information science, precision displacement metrology, and quantum electrodynamics. Additionally, coupled cavities that form a spectral doublet allow for parametric gain when incorporating mechanical elements. Here, we investigate normal-mode splitting in a pair of quarter-wave stub microwave cavities at room temperature and cryogenic environments in order to identify coupling mechanics for normal and superconducting systems. Superconducting quarter-wave stub cavities with a resonant frequency of 10 GHz are made from reactor-grade niobium and exhibit Q ranging from 105 to 109. We varied cavity-to-cavity coupling to observe several normal-mode splittings of increasing peak separation until we observed a mode crossing. The minimum observed peak separation was 7 MHz for room temperature tests and 200 kHz for cryogenic tests. We also report on values of an intrinsic quality factor for the tuning cavity as a dielectric rod is translated along its symmetry axis. The realization of coupled superconducting radio frequency (SRF) cavities of this type is a necessary step toward implementation of parametric SRF-mechanical gain.
Publisher: AIP Publishing
Date: 19-08-2020
DOI: 10.1063/5.0007451
Abstract: In this paper, we report on simulations of two types of high-Q 3-dimensional cavities: cylindrical TE011 and coaxial quarter-wave stub. We investigate the dependence of Q on the practical implementation tolerances of gaps between components, shape imperfections, and frequency tuning strategies. We find that cylindrical cavities can maintain high Q for designs that include frequency tuning and mechanical elements, provided extraordinary care is taken with shape and gap tolerance during construction and assembly. Coaxial stub cavities can be made with variable frequency while maintaining high Q, but they require more creativity to include a mechanical element. Finally, we report on a coaxial stub cavity, incorporating a conically shaped stub that confines the electric field near the stub’s tip, thus enhancing field–matter interactions near the tip.
Publisher: IOP Publishing
Date: 13-09-2019
Location: Australia
Location: United States of America
No related grants have been discovered for Jacob Pate.