Tests of Lorentz Invariance using a Microwave Resonator

Abstract

The frequencies of a cryogenic sapphire oscillator and a hydrogen maser are compared to set new constraints on a possible violation of Lorentz invariance. We determine the variation of the oscillator frequency as a function of its orientation (Michelson-Morley test) and of its velocity (Kennedy-Thorndike test) with respect to a preferred frame candidate. We constrain the corresponding parameters of the Mansouri and Sexl test theory to δ − β + 1/2 ≤ 3.4 × 10 −9 and β − α − 1 ≤ 4.1 × 10 −7 which is of the same order as the best previous result for the former and represents a 50 fold improvement for the latter. These results correspond to an improvement of our previously published limits [Wolf P. et al., Phys. Rev. Lett. 90, 6, 060402, (2003)] by about a factor 2. We describe the changes of the experiment, and show the new data that lead to that improvement.

The Confrontation Between General Relativity and Experiment

“…One of these is the Brillet-Hall experiment [69], which used a Fabry-Pérot laser interferometer. In a recent series of experiments, the frequencies of electromagnetic cavity oscillators in various orientations were compared with each other or with atomic clocks as a function of the orientation of the laboratory [438,254,293,20,376]. These placed bounds on −2 − 1 at the level of better than a part in 10 9 .…”

“…A variety of clock anisotropy experiments have been carried out to bound the electromagnetic parameters of the SME framework [227]. For example, the cavity experiments described above [438,254,293] placed bounds on the coefficients of the tensors˜e − and˜o + (see Section 2.2.4 for definitions) at the levels of 10 −14 and 10 −10 , respectively. Direct comparisons between atomic clocks based on different nuclear species place bounds on SME parameters in the neutron and proton sectors, depending on the nature of the transitions involved.…”

Long-term operation and performance of cryogenic sapphire oscillators

“…The oscillator allowed some new tests on Lorentz Invariance, up to a factor of 70 times more superior than previously [21][22][23]. The oscillator now supplies the stable frequency used to synthesize the frequencies that excite atomic transitions of the atomic clocks at SYRTE [24,25].…”

New-generation of cryogenic sapphire microwave oscillators for space, metrology, and scientific applications

“…Such oscillators have been serving quite well for scientific experiments, and also as the flywheel of primary Cs fountain clocks. [17][18][19] However, the liquid-He bath is incompatible with field applications requiring reliable and unsurveyed operation.…”