Abstract
We propose and demonstrate a test of Lorentz symmetry based on new, compact, and reliable quartz oscillator technology. Violations of Lorentz invariance in the matter and photon sector of the standard model extension generate anisotropies in particles’ inertial masses and the elastic constants of solids, giving rise to measurable anisotropies in the resonance frequencies of acoustic modes in solids. A first realization of such a “phonon-sector” test of Lorentz symmetry using room-temperature stress-compensated-cut crystals yields 120 h of data at a frequency resolution of and a limit of on the most weakly constrained neutron-sector coefficient of the standard model extension. Future experiments with cryogenic oscillators promise significant improvements in accuracy, opening up the potential for improved limits on Lorentz violation in the neutron, proton, electron, and photon sector.
- Received 8 December 2014
DOI:https://doi.org/10.1103/PhysRevX.6.011018
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Published by the American Physical Society
Popular Summary
The theories of quantum mechanics and general relativity have experienced great experimental successes, but these theories coexist as incompatible. However, different theoretical frameworks of unification allow, or even predict, small Lorentz invariance violation, that is, a violation of the paradigm that experimental results do not depend on orientation in space or velocity of the laboratory apparatus. Here, we attempt to uncover experimental evidence of Lorentz invariance violation by conducting precision frequency measurements of acoustic oscillations in quartz oscillators.
Using standard, robust, room-temperature technology, we set a quartz crystal rotating at roughly 0.3 Hz. We employ quartz crystals because they are largely unaffected by wobbling and tilting, and we study the crystal’s motion to look for physics not explained by the standard model. The crystal in our study is oscillating at 10 MHz, and our experiment is designed to measure deviations in oscillation frequency as a function of rotation, which would imply changes in inertial mass of the atoms making up the crystals. We shield our entire setup to minimize the effects of magnetic fields, and we collect roughly 120 hours’ worth of data. We find no evidence for Lorentz-violating anisotropies down to a level of roughly , thus verifying the overall isotropy of inertial masses of neutrons to 6 orders of magnitude higher precision than any previous direct laboratory experiment. We also discuss how future cryogenic quartz oscillators may make an additional 4 orders of magnitude improvement possible.
We expect that our findings will pave the way for improved tests of Lorentz invariance of neutrons, protons, electrons, and photons.