Spinor Bose–Einstein Condensate Magnetometry for Searches in Fundamental Physics

Abstract

This thesis investigates the use of a Spinor Bose-Einstein Condensate as a micrometer-scale quantum sensor for probing new fundamental physics. The sensor’s sensitivity is limited by a complex interplay of noise sources. We develop a theoretical framework to identify, model, and quantify these limitations, using the truncated Wigner approximation to capture interactioninduced shearing of the quantum noise and project sensitivity beyond the standard quantum limit. This model is supported by experimental efforts, including finite-element method simulations of an apertured magnetic shield and the development of a shot-noise-limited Faraday polarimeter. Applying the full framework, we show that an SBEC comagnetometer can set improved laboratory constraints on axion-like particle–proton couplings. In contrast, we find that the sensor’s small interaction volume limits its competitiveness for detecting high-frequency gravitational waves via spin-gravity coupling