Using Precision Oscillators and Interferometers to Test Fundamental Physics

The authors present current work at the University of Western Australia to test fundamental physics using precision phase and frequency measurements. The authors describe two experiments under development. Firstly, they describe a continuously rotating cryogenic microwave oscillator constructed to test local Lorentz invariance (LLI). Initial results improve limits set by previous non-rotating experiments by about an order of magnitude with only 3 months of data. Now, with over a year of data, they have reduced the noise floor by a factor of two. Secondly, they describe the development of a new, magnetically asymmetric, microwave interferometer with thermal noise limited readout, which will allow a sensitivity to the scalar and odd-parity coefficients for Lorentz violation in the photon sector of the standard model extension of parts in 10
⁸
and 10
¹²
respectively