Analysis Of Gravitational Correlation Effect In Atom Interferometry

There are four basic interaction forces in nature,namely gravity,strong interaction force,weak interaction force and electromagnetic interaction force.Gravity is described by general relativity while the other three forces are described by the standard model of parti-cle physics.It has been a dream of physicists to describe gravity and the other three forces in the unified theory.Therefore,it is of great significance to test the gravitational effect for understanding the essence of gravity and exploring the Grand Unified Theory.Einstein equivalent principle and gravitational waves are the basic hypothesis and important predic-tion of general relativity,respectively.The weak equivalence principle is an important part of the Einstein equivalence principle,and testing its equivalence is a direct test of the basis of general relativity.Gravitational waves is regarded as ripples in space-time,the detection of which can not only verify the correctness of general relativity,but also has great potential in obtaining the information of cosmic evolution.With the rapid development of atomic interferometry,the atom interferometers have been widely applied in various precision mea-suring experiments,and also gradually used to test various gravitational correlation effects.The accuracy of experimental verification depends not only on the current level of exper-imental technology,but also on the accuracy of theoretical models for measuring various gravitational correlation effects by the atom interferometers.However,the current exper-imental accuracy of atom interferometers is relatively low in testing the weak equivalent principle,existing some large systematic errors in the measurement.The current theoretical models of atom interferometers in detecting gravitational waves also has some limitations.Therefore,it is of great scientific significance to establish a high-precision theoretical mod-el for the atom interferometer and explore the corresponding noises suppression scheme,which will provide the theoretical basis for the higher precision test of the gravitational correlation effects.This paper mainly focuses on the test of weak equivalence principle and the detection of gravitational waves by using the atom interferometers.The research includes:(1)A high precision theoretical model is established and a scheme to suppress the main noises is proposed for the atom interferometer to test weak equivalence principle.Based on Einstein equivalent principle,we first adopt a space-coordinate translation to construct a freely falling coordinate system where the uniform part of the gravitational field acting on the atoms vanishes,and further made a space-coordinate stretching associated with the gravity gradient to make the inhomogeneous part of the gravitational field felt by the atoms vanish,constructing an equivalent effective reference system.This operation transforms the gravitational effects on atoms into the laser beams,simplifying the calculation and establishing a high-precision theoretical model for testing weak equivalence principle with the atom interferometer.Based on this model,we put forward an improvement to the frequency shift gravity gradient compensation technique to eliminate the coupling of Raman-pulse-duration effect and gravity gradient related to initial position and velocity,and discuss the feasibility of testing WEP with microscopic particles at the 10^-14level.(2)A high-precision and universal theoretical model is established and the detection capabilities of different atomic interferencing detectors are analyzed.Combining the Eikonal equation in general relativity with atom interferometer,the perturbative phase of gravitational wave to the lasers is calculated.In addition,the traditional Bord(?) ABCD matrix method is adopted to calculate the perturbative phase of gravitational waves to atoms.Then,we can obtain a general vectorial expression of the gravitational wave perturbation on the atom interferometer.Based on this,we discussed an analytical study about the dependence of response function for the plus and cross polarizations on the azimuth,which provides a nec-essary foundation to determine the optimum detection positions for the future gravitational wave detectors.Finally,the main noises are analyzed,and the detection capability of the detector is evaluated according to the theoretical model.