39 research outputs found
Matter-wave Tests of the Gravitational Redshift in Space
A recent measurement of the gravitational redshift was based on interference
of matter waves. Operation in microgravity can improve it by a factor of
and, in some models, even .Comment: Talk given at the Fifth Meeting on CPT and Lorentz Symmetry, at
Indiana University, Bloomington, IN. Corrected problem with Figur
Force-Free Gravitational Redshift: Proposed Gravitational Aharonov-Bohm experiment
We propose a feasible laboratory interferometry experiment with matter waves
in a gravitational potential caused by a pair of artificial field-generating
masses. It will demonstrate that the presence of these masses (and, for moving
atoms, time dilation) induces a phase shift, even if it does not cause any
classical force. The phase shift is identical to that produced by the
gravitational redshift (or time dilation) of clocks ticking at the atom's
Compton frequency. In analogy to the Aharonov-Bohm effect in electromagnetism,
the quantum mechanical phase is a function of the gravitational potential and
not the classical forces.Comment: Updated to published versio
Precision tests of General Relativity with Matter Waves
We review the physics of atoms and clocks in weakly curved spacetime, and how
each may be used to test the Einstein Equivalence Principle (EEP) in the
context of the minimal Standard Model Extension (mSME). We find that
conventional clocks and matter-wave interferometers are sensitive to the same
kinds of EEP-violating physics. We show that the analogy between matter-waves
and clocks remains true for systems beyond the semiclassical limit. We
quantitatively compare the experimentally observable signals for EEP violation
in matter-wave experiments. We find that comparisons of Li and Li
are particularly sensitive to such anomalies. Tests involving unstable
isotopes, for which matter-wave interferometers are well suited, may further
improve the sensitivity of EEP tests.Comment: Conference Proceedings for talk given in January, 2011 at the Winter
Colloquium on the Physics of Quantum Electronics. Submitted to the Journal of
Modern Optic
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Particle-Accelerator Constraints on Isotropic Modifications of the Speed of Light
The absence of vacuum Cherenkov radiation for 104.5 GeV electrons and positrons at LEP combined with the observed stability of 300 GeV photons at the Tevatron constrains deviations of the speed of light relative to the maximal attainable speed of electrons. Within the Standard-Model Extension (SME), the limit is extracted, which sharpens previous bounds by more than 3 orders of magnitude. The potential for further refinements of this limit with terrestrial experiments and astrophysical observations is discussed.Physic
Improved Constraints on Isotropic Shift and Anisotropies of the Speed of Light using Rotating Cryogenic Sapphire Oscillators
We demonstrate that Michelson-Morley tests, which detect direction-dependent
anisotropies in the speed of light, can also be used to place limits upon
isotropic deviations of the vacuum speed of light from , as described by the
photon sector Standard Model Extension (SME) parameter . A
shift in the speed of light that is isotropic in one inertial frame implies
anisotropic shifts in others. Using observer Lorentz covariance, we derive the
time-dependent variations in the relative resonance frequencies of a pair of
electromagnetic resonators that would be generated by such a shift in the rest
frame of the Sun. A new analysis of a recent experimental test of relativity
using this result constrains with a precision of
. This represents the first constraint on
by a Michelson-Morley experiment and the first analysis
of a single experiment to simultaneously set limits on all nine
non-birefringent terms in the photon sector of the SME
Gravitational Redshift, Equivalence Principle, and Matter Waves
We review matter wave and clock comparison tests of the gravitational
redshift. To elucidate their relationship to tests of the universality of free
fall (UFF), we define scenarios wherein redshift violations are coupled to
violations of UFF ("type II"), or independent of UFF violations ("type III"),
respectively. Clock comparisons and atom interferometers are sensitive to
similar effects in type II and precisely the same effects in type III
scenarios, although type III violations remain poorly constrained. Finally, we
describe the "Geodesic Explorer," a conceptual spaceborne atom interferometer
that will test the gravitational redshift with an accuracy 5 orders of
magnitude better than current terrestrial redshift experiments for type II
scenarios and 12 orders of magnitude better for type III.Comment: Work in progress. 11 page