We present atom-interferometer tests of the local Lorentz invariance of post-Newtonian gravity. An experiment probing for anomalous vertical gravity on Earth, which has already been performed by us, uses the highest-resolution atomic gravimeter so far. The influence of Lorentz violation in electrodynamics is also taken into account, resulting in combined bounds on Lorentz violation in gravity and electrodynamics. Expressed within the standard model extension or Nordtvedt's anisotropic universe model, we limit twelve linear combinations of seven coefficients for Lorentz violation at the part per billion level, from which we derive limits on six coefficients (and seven when taking into account additional data from lunar laser ranging). We also discuss the use of horizontal interferometers, including atom-chip or guided-atom devices, which potentially allow the use of longer coherence times in order to achieve higher sensitivity.
We perform a comprehensive study of the signatures of Lorentz violation in electrodynamics on the Cosmic Microwave Background (CMB) anisotropies. In the framework of the minimal Standard Model Extension (SME), we consider effects generated by renormalizable operators, both CPT-odd and CPT-even. These operators are responsible for sourcing, respectively, cosmic birefringence and circular polarization. We propagate jointly the effects of all the relevant Lorentz-violating parameters to CMB observables and provide constraints with the most recent CMB datasets. We bound the CPT-even coefficient to…
A New Limit on Signals of Lorentz Violation in Electrodynamics
我们描述了一个实验的结果来测试时空各向异性条款,可能存在的洛伦兹违反。该装置由一对圆柱形超导腔稳定振荡器组成,振荡器工作在TM_{010}模式下,一个轴为东西向,另一个轴垂直。空间各向异性检测通过监测拍频在恒星率及其第一谐波。我们在10^{13}中的一部分没有看到各向异性。这使得一般标准模型扩展中的四个参数线性组合具有可比性的界限,而其他三个参数的界限较弱,<4 x 10^{-9}。
We study a non-local ghost-free Lorentz invariant modification of the Maxwell equations in four- and higher-dimensional flat spacetimes. We construct solutions of these equations for stationary charged and magnetized objects and use them to find the field created by such objects moving with the speed of light.