量子气体的一个重要应用是在精密测量物理中实现高精度的原子钟。2014年美国标准局的叶军实验组创造了中性原子光钟的世界纪录－相对精准度和稳定性双双被推进到了10^-18水平。国际上各国对原子光钟研究的巨大投入必能将原子光钟的精度推向更高水平。但原子相互作用所导致的原子钟频移始终是提高原子钟精度的瓶颈因素。本申请项目旨在建立和发展原子钟频移理论，高精度的定量研究原子相互作用效应。我们将具体研究（1）原子间的两体短程高分波碰撞，（2）原子间的三体相互作用，（3）三维光晶格原子钟的电偶极矩相互作用对原子钟的影响。我们的研究将为原子钟在好于10^-20的水平上提供实验与理论比对的基础，此外为实验上抑制相互作用频移提供新思路。

An important application of quantum gases is the realization of high-precision atomic clocks in precision measurement physics. In 2014, the NIST experimental group led by Professor Ye Jun created a world record of neutral optical atomic clocks - both the relative precision and stability were advanced to the 10^-18 level. The world-wide tremendous investment in the research of optical atomic clocks is bound to push the clocks to better performance. However the atomic interactions always pose as a bottleneck factor for improving the precision of neutral optical atomic clocks. This proposal application aims to establish and develop a high precision theory for neutral optical atomic clock frequency shifts due to interatomic interactions. Specifically, we will study (1) different partial wave collisions due to pairwise interactions, (2) the three-body interaction, and (3) the electric dipole interaction in three-dimensional optical lattice atomic clocks, and determine their effects on the clock shift. Our study will lay the basis for experimental and theoretical comparison of atomic clocks at levels better than 10^-20, and provide new ideas for experimentally suppressing the frequency shift due to interatomic interactions.