Eugene Ivanov

Improved test of Lorentz invariance in electrodynamics using rotating cryogenic sapphire oscillators

We present new results from our test of Lorentz invariance, which compares two orthogonal cryogenic sapphire microwave oscillators rotating in the lab. We have now acquired over 1 year of data, allowing us to avoid the short data set approximation (less than 1 year) that assumes no cancellation occurs between the {kappa}-tilde{sub e-} and {kappa}-tilde{sub o+} parameters from the photon sector of the standard model extension. Thus, we are able to place independent limits on all eight {kappa}-tilde{sub e-} and {kappa}-tilde{sub o+} parameters. Our result represents up to a factor of 10 improvement over previous nonrotating measurements (which independently constrained seven parameters) and is a slight improvement (except for {kappa}-tilde{sub e-}{sup ZZ}) over results from previous rotating experiments that assumed the short data set approximation. Also, an analysis in the Robertson-Mansouri-Sexl framework allows us to place a new limit on the isotropy parameter P{sub MM}={delta}-{beta}+(1/2) of 9.4(8.1)x10{sup -11}, an improvement of a factor of 2.

Analysis of the rutile-ring method of frequency-temperature compensation of a high-Q whispering gallery sapphire resonator

Rigorous analysis of the rutile-ring method of frequency-temperature compensating of a high-Q sapphire resonator has been presented. A high Q-factor of 30 million was obtained with an annulment temperature of 56 K mainly limited by dielectric loss. The condition to obtain a low spurious mode density, high-q resonance that has a low susceptibility to environmental effects was established. It is desirable to design the compensation in the regime dominated by an antiresonance effect due to the rutile rings.The rutile-ring method of dielectrically frequency-temperature compensating a high-Q whispering gallery (WG) sapphire resonator is presented. Two and three-dimensional finite element (FE) analysis has been implemented to design and analyze the performance of such resonators, with excellent agreement between theory and experiment. A high-Q factor of 30 million at 13 GHz, and compensation temperature of 56 K was obtained. It is shown the frequency-temperature compensation can occur either because the rutile adds a small perturbation to the sapphire resonator or because of a mode interaction with a resonant mode in the rutile. The characteristics of both of these methods are described, and it is shown that for high frequency stability, it is best to compensate perturbatively.