Testing the Theory of Relativity Using Ultra-stable Cryogenic Sapphire Oscillators

We will perform an optimized Michelson-Morley-type experiment with co-rotating cryogenic microwave and optical resonators. The experiment compares the resonance frequencies of two cryogenic microwave and two cryogenic optical resonators while they are being continuously rotated together over a time span of one year using a custom-made high-precision low noise turntable system. We will employ optical sapphire cavities that are especially designed for cryogenic operation with theoretical thermal noise limited relative frequency stability below 3x10-17. Achieving this level of stability in the frequency stabilization of lasers would be of great benefit for a variety of other experiments and technical applications, like optical clocks and high-resolution spectroscopy, e.g. in material science. The combination of these highly stable resonators with a low-noise turntable system permits a search for violations of Lorentz invariance in 10-20 range, corresponding to more than a 100-fold improvement in precision of modern Michelson-Morley experiments.