一般平动参考系中的功能原理探讨外文翻译资料

本科毕业设计（论文）

外文翻译

Effective inertial frame in an atom interferometric test of the equivalence principle

Chris Overstreet, Peter Asenbaum, Tim Kovachy, Remy Notermans,

Jason M.Hogan, and Mark A. Kasevich

Departrhent of Physics, Stanford University, Stanford, California 94305lowast;

(Dated: December 1, 2017)

In an ideal test of the equivalence principle, the test masses fall in a common inertial frame. A real experiment is affected by gravity gradients, which introduce systematic errors by coupling to initial kinematic differences between the test masses. We demonstrate a method that reduces the sensitivity of a dual-species atom interferometer to initial kinematics by using a frequency shift of the mirror pulse to create an effective inertial frame for both atomic species. This suppresses the gravity-gradient-induced dependence of the differential phase on initial kinematic differences by a factor of 100 and enables a precise measurement of these differences. We realize a relative precision of ∆g/g asymp; 6 times; 10^minus;11 per shot, which improves on the best previous result for a dual-species atom interferometer by more than three orders of magnitude. By suppressing gravity gradient systematic errors to below one part in 10¹³, these results pave the way for an atomic test of the equivalence principle at an accuracy comparable with state-of-the-art classical tests.

PACS numbers: 37.25. k, 04.80.Cc, 03.75.-b, 06.20.-f

The equivalence principle lies at the heart of general relativity, and efforts to test its validity with increasing precision for a variety of test objects are at the forefront of experimental physics [1-14]. Many of these experiments probe the weak equivalence principle (WEP), which stipulates the universality of free fall [15]. In addition to testing a fundamental aspect of general relativity, WEP tests can be used to search for new interactions and for dark matter [16, 17].

All WEP tests operate under the same general principle-they compare the gravitational accelerations of two test masses of different composition. In an ideal thought experiment, this comparison would occur in a uniform gravitational field, making the measurement insensitive to the initial kinematics of the test masses. However, in realistic experimental setups, gravity gradients are present. Gravity gradients cause the measured acceleration of a given test mass to vary linearly as a function of its initial position and velocity. As a consequence, mismatches in the initial kinematics of the test masses can appear as a spurious WEP violation if not characterized to the necessary accuracy. This coupling of initial kinematics to gravity gradients is a leading systematic error in WEP tests based on atom interferometry[11, 18].

It is relevant to consider the ramifications of this effect for Earths gravity gradient, which is approximately T_ZZ=3times;g/m in the vertical direction. To lowest order, the differential acceleration that the gravity gradient induces between the test masses A and B is g_A-g_B=T_ZZ[Delta;z Delta;vT] equiv; T_ZZDelta;z, where Delta;z=z_A-z_B, Delta;v=v_A-v_B, g_i, z_i and v_i are the respective gravitational acceleration, initial position, and initial velocity of test mass iisin;{A,B} and T is the time interval over which the acceleration measurement occurs. This implies, for example, that an equivalence principle test with relative accuracy 2(g_A-g_B )/( g_A g_B )= (g_A-g_B )/gasymp; requires relative displacements arising from initial kinematics to be controlled at the level of 30 nm.

In this work, we experimentally demonstrate a method to make a dual-species atom interferometric WEP test [3-8] insensitive to initial kinematics. Following the proposal of Roura [19], the optical frequency is shifted for the mirror sequence of a light-pulse Mach-Zehnder atom interferometer [20, 21], producing a phase shift proportional to the average vertical displacement Delta;z during the interferometer [22]. An appropriate choice of this frequency shift counteracts the corresponding phase shift from the gravity gradient [19], creating an effective inertial frame. Although the interferometer trajectories remain perturbed by the gravity gradient as a function of initial position and velocity, the interferometer phase becomes insensitive to these perturbations. We refer to this method as frequency shift gravity gradient compensation (FSGG compensation). Using FSGG compensation in a long duration/large momentum transfer (long T /LMT) dual species interferometer with ⁸⁵Rb and ⁸⁷ Rb,we reduce the sensitivity to initial kinematic mismatches to less than 1% of its original value. Moreover, we introduce a technique to determine the correct frequency shift without needing to independently measure or calculate the gravity gradient. An analogous method to FSGG compensation is not currently known for classical free-fall WEP tests.

The core features of the experimental apparatus have been described in previous work [23-27]. Some modifications to the atom source have been made in order to generate an ultracold dual species cloud (earlier experiments used only ⁸⁷ Rb). Approximately ⁸⁷ Rb atoms are loaded from a 2D-MOT into a 3D-MOT. Subsequently, forced microwave evaporation is performed on the ⁸⁷ Rb atoms in a quadrupole and then a time-orbiting potent

剩余内容已隐藏，支付完成后下载完整资料

英语原文共 5 页，剩余内容已隐藏，支付完成后下载完整资料

资料编号：[272039]，资料为PDF文档或Word文档，PDF文档可免费转换为Word