quantum optics with cold atoms

The advances in laser cooling and trapping techniques allow ultra-cold atoms to be routinely prepared and precisely controlled for the study of quantum physics. In this talk, I will present our work in using cold atoms, especially high-lying Rydberg atoms to study novel quantum effects and their applications in quantum optics.Realization of large scale quantum system, e.g. a global quantum network, relies on quantum memories with long lifetimes (seconds). With the combination of magic trapping technique and Dynamical Decoupling sequence, we have reduced the differential light shifts of the atomic ground states to a sub-Hz level and achieved a memory lifetime of 16 seconds.Achieving deterministic quantum operations, on the other hand, requires strongly-interacting systems. We explore highly excited Rydberg atoms towards this goal and demonstrate Rydberg excitation blockade and many-body Rabi oscillations. We also developed a state-insensitive optical lattice which allows simultaneous trapping of both the Rydberg and the ground state. Building on the achieved Rydberg blockade and state-insensitive trapping, we have realized a deterministic single photon source and the entanglement between light and an optical atomic (Rydberg) excitation.Finally, we demonstrate the simultaneous achievement of the two essential capabilities for quantum information processing, fast quantum state generation and long-term storage, by direct optical coupling of ground state to Rydberg p states. The Rydberg levels are exploited for interactions while the ground atomic levels are employed for the preservation of non-classical state.