量子信息科学以量子比特作为信息单元，量子比特的物理载体是任何可执行幺正变换的两能态量子系统。碱金属原子拥有长寿命的超精细基态，其可以作为量子比特的逻辑基矢实现信息的写入和读出；利用光与原子的纠缠，可以实现传递信息的飞行量子比特（光子）与存储信息的量子比特（原子）的相互作用；基于单原子量子比特的受控非门（CNOT门）是量子逻辑运算的基本构成单元，宏观数量的量子逻辑门可以实现量子计算。本项目在我们小组已掌握的单原子冷却与俘获的实验基础上，实现单原子量子态的制备和探测，进而实现基于单原子量子比特的可控操作。主要内容包括：(1) 魔术波长微米尺度光学偶极阱系统的研究；（2）光学阱中单原子超精细基态以及Zeeman磁量子态的制备及识别实验技术研究；（3） 基于单原子量子比特的相干操控实验技术研究及量子比特的退相干机制研究；（4）量子比特的扩展性研究探索。

The quantum bit (qubit) is the units of the quantum information. The qubit can be stored in any two state systems which can accomplish unitary transformation. Neutral atoms also exhibit favorable properties for storing and processing quantum information and represent an alternative physical system to perform quantum computation. Their hyperfine ground states are readily prepared in pure quantum states including state superpositions and can realize the writing-in and reading-out of information. Using the entanglement of photon and atom, the interaction between the quantum state of fly qubit for transferring information and the quantum state of carrier qubit， which can be applied for storage and transfer of quantum information and meaningful for quantum network and quantum communication. Moreover, by processing qubits with quantum gates, a quantum computer is fundamentally superior to classical computers in certain cases. As the CNOT gate of quantum bit of single atom is basic component of quantum logical calculation, a large number of quantum logical gate can realize quantum calculation. Based on the previous work of a single cesium atom prepared in a large-magnetic-gradient magneto-optical trap (MOT), we study the initialization, readout, and high-speed manipulation of a qubit stored in a single cesium atom trapped in a micrometer-sized optical trap. The main contents of the study including: (1) Studying microscopic magic-wavelength optical dipole trap; (2) Preparing the trapped atom into specific hyperfine states or Zeeman states by optical pumping. The state selective detection is performed by a laser which is resonant to the atomic transition and thus pushes out the FORT only it is in the specific state; (3) Performing the single qubit operations using two-photon Raman transitions; Measuring the coherence time of the qubit using Ramsey spectroscopy and presenting an analytical model to interpret the experimental data and identify the homogeneous and inhomogeneous dephasing mechanisms；（4）Studying on the extesion and appliciation of the qubit.