| Rydberg atoms are highly excited atoms with large principal quantum number n, of which the size is very big (r～n2),and the lifetimes are very long (-n3). According to the large polarizabilities of Rydberg atoms (～n7), Rydberg atoms are very sensitive to external field and therefore are easy to control with external field. Van de Waals or dipole blockade effects were investigated in the ensemble of Rydberg atoms because of their strong long-range Van de Waals or dipole-dipole interactions. People have realized the excitations of single Rydberg atoms and manipulation of quantum gates based on blockade effects. Autler-Townes splittings are investigated in the strong interacting Rydberg atoms. Dark-state polaritons are generated which conbine the photons and blockaded Rydberg superatoms to implement the light storage and source of single photon. All of the above make the Rydberg atoms potential candidate for implementation of quantum storage and quantum information.Ultracold cesium atoms are trapped in Magneto-Optical Trap (MOT) with the temperature of about 100μK, atoms number of about 5×107 and diameter of atom cloud of about 700μm. The ultracold cesium atoms are excited to Rydberg states via 6S1/2â†'6P3/2â†'nD/nS two-photon transition. Then the Rydberg atoms are ionized for detection.This dissertation mainly investigated the quantum interference effect theoretically and experimentally in the ultra cold cesium Rydberg atoms, including:1. Solve the master equation of density matrix of Rydberg atom in the semiclassical model describing the interactions between lasers and cascade 3-level system. Simulate the A-T splitting spectra in cesium Rydberg atoms with considering the interactions between Rydberg atoms empirically. Investigate the influence of coupling light on A-T splitting by changing the intensity and detuning of coupling laser. Investigate the influence of interactions between Rydberg atoms through tunning the density of Rydberg atoms and principal quantum number n. A parameter η which could be considered as criterion of system interference is proposed.2. Stark energies maps are calculated numerically. Analyze the formation of avoided crossing of nS state mixing with (n-4) manifold. Two avoided crossing points of 49S mixing with n= 45 manifold around 4.3 and 5.5 V/cm were observed which agrees with theoretical predictions very well.3. Prepare the high -l states by applying a pulsed electric field via state transfer through the avoided crossings of nS mixing with (n-4) manifold. Stronger field leads to larger state transfer. The processes of state transfer are almost linearly dependent with the density of atoms. The electric field amplitudes corresponding to the same state transfer ratio of different principal quantum number n are n-5.89±0.4dependent. Dynamical evolution processes are observed of the state transfer by changing the width of electric field pulse. The stronger the field is, the faster the evolution saturates and the higher ratio of the saturation is. The influences of electric field amplitude, free ions and principal quantum number are investigated. The interference effects of the state transfer are investigated through applying two identical electric field pulses, and the shorter the width of the pulse is, the more obvious the interference oscillation will be observed. Simple explanations with evolutions of high-l Rydberg states wavefunctions are presented.The innovations of the works includes:1. Investigate the effects of long-range strong interactions on the interference between lasers and Rydbeg atoms theoretically and experimentaly.2. Avoided crossing points of Rydberg states Stark maps are observed. The state transfer processes of nSâ†'(n-4) high-l induced by electric field are investigated. The dynamical evolutions and interference characteristics of the state transfer are investigated. |
PDF Full Text Request