Feasibility Study Of The Weak Equivalence Principle Test By Cold Atom Interferometer In Space

The microgravity environment in space can greatly extend the free evolving time of the cold atom interferometers?CAI?,and the noises induced by the magnetic field,the gravity gradient and the overlap of the atomic clouds etc.,can be greatly suppressed,so the precision of the space-based CAI can be much higher than the ground-based counterparts.At the same time,the experimental precision of CAI-based the weak equivalence principle?WEP?test in space is expected to be 7 orders higher than the similar experiment on the ground in magnitude.In this thesis,the detailed feasibility analysis and scheme design of CAI-based WEP test experiment in space are presented.The main innovative perspectives and results are listed in the following:?1?The result shows that the atom pair of the non-isotopes is more sensitive than the atom pair of the isotopes to the WEP-violation phenomenology.Moreover,the sensitivities of the common materials to WEP-violation phenomenology are calibrated.?2?We presented a new spectral analysis method to analyze the experimental data in the atomic interference experiment,and this method effectively suppresses the DC noise and the other noises caused by the non-sensitive frequency band in case of the inertia pointing mode of aircraft.Using the Lissajous curve fitting method,the differential phase from the differential measurement is analyzed,thus the interference information is obtained,and the last noise suppression effect is better than that of the elliptic fitting.?3?Through analyzing the results and calculating the various errors and noises by using the differential phase in CAI-based WEP test,it shows that the quantum projection noise,the gravity gradient and the magnetic field are the main sources of noise to further improve the precision of CAI-based WEP test in space.The precision of the CAI-based WEP test using a pair of atoms ⁸⁷Rb-⁸⁵Rb and a pair of atoms ⁸⁷Rb-⁴¹K are calculated,respectively,the results indicate that the precision of 5×10^-1515 can be achieved with a pair of atoms⁸⁷Rb-⁴¹K through one year?s experiment.?4?The expansion-rate-selection method is firstly proposed to suppress the wavefront aberration error in both isotopic and non-isotopic atom interferometers,thus the wavefront aberration error is effectively reduced by about 10 times.In the 10-meter-high atom fountain on the ground,the temperature of atom clouds ⁸⁷Rb-⁸⁵Rb and ⁸⁷Rb-⁴¹K both are1-nK,the standard deviations to the E?tv?s coefficient caused by the wavefront aberration in WEP test are 1.3×10^-14 and 3.0×10^-13.Furthermore,the suppression ratios relative to gravity measurement are 460 and 28,respectively.?5?The experimental scheme for CAI-based WEP test in space is designed.With this scheme,the dual-atom chip structure can effectively avoids the unmixing of the two atomic clouds and well control the temperature of the two clouds respectively,this scheme will have a greater application prospect for the atom pair of non-isotopes with different expansive rate.