单原子在光阱中的极化率、超极化率精确计算及其在相干量子操控中的应用

囚禁在光学偶极阱中的单原子在量子信息和精密测量中均有重要的应用。限制量子操作保真度的一个重要因素是原子在光场中的光频移导致的自旋相干态的失相，这使得寻找魔幻条件成为一个重要的研究课题。最新的研究显示，在外磁场下光偶极阱中原子的光频移必须考虑到高阶的超极化率项，从而得到新型的“魔幻强度”条件，而非以往的“魔幻波长”条件。同时，我们已经在实验上观察到该现象，实现了单原子的魔幻强度囚禁，获得超长的相干时间和无损相干性的快速转移，并且测得了Rb-87原子的四阶超极化率。进一步的实验将实现魔幻囚禁的单原子阵列，并进行寻址、单比特位相门操控以及原子间的相互纠缠等实验，在此过程中需要大量的理论计算和模拟，以确定最优的参数配置。本项目将分析计算偶极阱阵列中原子基态的微分频移和囚禁光波长、光强以及外加磁场的关系，为单原子量子比特的寻址、位相门操作提供理论指导；并在新的理论基础上寻找基态和激发态双魔幻条件。

Single atoms trapped in optical dipole traps have important applications in quantum information and precision measurements. Although the clock states have excellent coherence properties in a field free environment, fluctuations of optical and magnetic trapping and bias fields lead to differential shifts of the clock state energies causing decoherence. According to the latest calculations, in the external magnetic field and optical dipole trap atoms by light shift must take into account the hyperpolarizability term, so as to obtain new magic intensity conditions, rather than the previous magic wavelength. At the same time, we have demonstrated the magic intensity trap in the experiment and measured previously neglected ground state hyperpolarizability. By virtue of the magic light intensity technique, the measured coherence time of the mobile qubits is the same as the static qubits. Further experimentations for single atoms trapped in optical dipole trap array will conduct the research of quantum speed limit exploration, quantum gate operation and entanglement. It requires a lot of theoretical calculations and numerical simulations to determine the optimal parameter configuration. This project is to analyze the relationship between the differential light shift of clock state and trapping light wavelength, intensity and magnetic field, to provide theoretical guidance for addressing and single atomic qubit quantum gate operation. Furthermore, we will be looking for double magic conditions for ground and excited states of alkali atoms on the basis of new theories.