Single Atomic Qubit Coherent Transfer And Two Atom Controlled Collision In Optical Dipole Trap

In this thesis, we have done works on the manipulations of single atomic qubit in an optical dipole trap. The magic light intensity trap and coherent transfer of the single atom qubit are realized. The collision between two atoms with hetero-nuclear in the ground states, together with the light-assistant colli-sion, are also studied in details, and the loss rate constants are measured under certain conditions. In this paper, the main contents and innovation points are shown as follows:1. Realization of magic trap and coherent transfer for single atomic qubit.According to the theory proposed by A. Derevianko in 2010, a kind of magic trap can be realized by using a magnetic field parallel to the optic axis of the laser dipole trap, which can compensate the differential light shift caused by the laser dipole trap with circular polarization.We have obtained a magic trap by eliminating the first order sensitivity to the trapping laser field. In this special trap, the inhomogeneous decoherence time can be extended to the several seconds. Under the magnetic field with some fluctuations, we have got the coherent time of 200 ms which is two orders of magnitude longer than that in a linearly polarized dipole trap. Using the technology of magic trap, we can transfer the atom from one trap to another nearly without decoherence.Our results pave the way for constructing a scalable quantum-computing architectures with single atoms trapped in an array of dipole traps.2. Measurement of the hyper polarizability of 87Rb in the laser dipole trap.We have observed the effect of hyper-polarizability in the dipole trap and measured the coefficient of the differential light shift caused by this effect. The measured value will be of great importance in the field of precision measurement in the laser trap.3. Observation of single atomic spin-rotation coupling effect in the laser dipole trap.Spin-rotation coupling effect is a pure quantum mechanical effect. When the static atoms are in a rotating magnetic field, or atoms in the static magnetic field with a circular orbit, a frequency shift will be attached to the magnetic sublevels, and the shift value is equal to the rotation frequency. Using a rapidly rotating dipole trap (1-3 kHz) to drive the single atom, we can observe the atomic spin-rotation coupling effect.4. Measurement of ground states and light-assisted collisional loss rate constants of two hetero-nuclear atoms in dipole trap.Two hetero-nuclear Rb atoms, which have been prepared to a certain hy-perfine levels of ground states, are loaded in a dipole trap and then the loss of atoms caused by the collision is meaured. We have measured four combinations of ground-states. Experiments have shown two channels which are a rapid response channel (87Rb is in the upper level) and a slow one (87Rb is in the lower level, 85Rb is in the upper level), also the collisional loss rate constants are measured precisely.By applying a near resonance light of 85Rb D2 line closed transition, we implement the light-assisted collision of hetero-nuclear two atoms. We measure the collisional loss rate constants precisely. Compared with the complicated collisions in ensemble systems, the superiority of our experiment method is shown to be graceful and reliable.Our experiment method also can be applied to various collision system, such as excited state collision, ultracold chemistry, and quantum information processing based on collision.