We consider the role of the internal kinetic energy of bound systems of matter in tests of the Einstein equivalence principle. Using the gravitational sector of the standard model extension, we show that stringent limits on equivalence principle viol
ations in antimatter can be indirectly obtained from tests using bound systems of normal matter. We estimate the bound kinetic energy of nucleons in a range of light atomic species using Greens function Monte Carlo calculations, and for heavier species using a Woods-Saxon model. We survey the sensitivities of existing and planned experimental tests of the equivalence principle, and report new constraints at the level of between a few parts in $10^{6}$ and parts in $10^{8}$ on violations of the equivalence principle for matter and antimatter.
We propose using a Stark interference technique to directly measure the odd-parity c_{0j} components of the electron sector c_{mu u} tensor of the Standard-Model Extension. This technique has been shown to be a sensitive probe of parity violation in
atomic dysprosium in a low-energy, tabletop experiment, and may also be straightforwardly applied to test Lorentz invariance. We estimate that such an experiment may be sensitive to c_{0j} coefficients as small as 10^{-18}.
We present a consistent, generally covariant quantization of light for non-vacuum birefringent, Lorentz-symmetry breaking electrodynamics in the context of the Standard Model Extension. We find that the number of light quanta in the field is not fram
e independent, and that the interaction of the quantized field with matter is necessarily birefringent. We also show that the conventional Lorenz gauge condition used to restrict the photon-mode basis to solutions of the Maxwell equations must be weakened to consistently describe Lorentz symmetry violation.
We show that Wolf et al.s 2011 analysis in Class. Quant. Grav. v28, 145017 does not support their conclusions, in particular that there is no redshift effect in atom interferometers except in inconsistent dual Lagrangian formalisms. Wolf et al. misap
ply both Schiffs conjecture and the results of their own analysis when they conclude that atom interferometers are tests of the weak equivalence principle which only become redshift tests if Schiffs conjecture is invalid. Atom interferometers are direct redshift tests in any formalism.
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 dilat
ion) 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 atoms 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.
The recent realization that atom interferometers (AIs) can be used to test the gravitational redshift tests has proven to be controversial in some quarters. Here, we address the issues raised against the interpretation of AIs as redshift tests, reaff
irming the fact that Mueller et al. [Nature 463, 926 (2010)] indeed report a gravitational redshift test.
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 $^{6}$Li and $^{7}$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.
We investigate leading order deviations from general relativity that violate the Einstein equivalence principle in the gravitational standard model extension. We show that redshift experiments based on matter waves and clock comparisons are equivalen
t to one another. Consideration of torsion balance tests, along with matter wave, microwave, optical, and Mossbauer clock tests, yields comprehensive limits on spin-independent Einstein equivalence principle-violating standard model extension terms at the $10^{-6}$ level.
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.
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 $c$, as described by the photon sector Stand
ard Model Extension (SME) parameter $tilde{kappa}_{tr}$. 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 $tilde{kappa}_{tr}$ with a precision of $7.4times10^{-9}$. This represents the first constraint on $tilde{kappa}_{tr}$ 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.
