Testing Microscopic Theories of Electric Field Fluctuations Over Metal Films

Stochastic electric and magnetic fields are present near metal surfaces. These fluctuations can have a number of experimental consequences. They can lead to extraneous friction and frequency noise in scanning probe experiments, limiting the achievable force sensitivity. They can furthermore result in decoherence in nitrogen vacancy center and ion trap quantum computing experiments. The theoretical description of these fluctuations is a topic of active research.^1–3 To test these theories we are carrying out measurements of electric field fluctuations over thin metal films at room temperature in high vacuum. In these experiments we infer the height dependence of stochastic electric fields and electric field gradients, from measurements of non-contact friction and frequency noise, respectively. This data can be used to decide among competing theories – are the stochastic electric fields caused by dielectric fluctuations of surface adsorbates or thermal fluctuations of electrons in the underlying metal? The study of electric field fluctuations could be a powerful tool for probing the electronic structure of quantum materials.<br/> <br/>(1) Brownnutt, M.; Kumph, M.; Rabl, P.; Blatt, R. Ion-Trap Measurements of Electric-Field Noise near Surfaces. <i>Rev. Mod. Phys.</i> <b>2015</b>, <i>87</i> (4), 1419–1482. https://doi.org/10.1103/RevModPhys.87.1419.<br/>(2) Loring, R. F. Noncontact Friction in Electric Force Microscopy over a Conductor with Nonlocal Dielectric Response. <i>J. Phys. Chem. A</i> <b>2022</b>, <i>126</i> (36), 6309–6313. https://doi.org/10.1021/acs.jpca.2c04428.<br/>(3) Hite, D. A.; Colombe, Y.; Wilson, A. C.; Allcock, D. T. C.; Leibfried, D.; Wineland, D. J.; Pappas, D. P. Surface Science for Improved Ion Traps. <i>MRS Bull.</i> <b>2013</b>, <i>38</i> (10), 826–833. https://doi.org/10.1557/mrs.2013.207.