Quantum information processing has originated from new insight that a quantum state serves as a sort of information. The peculiar nature of the quantum world opens up the way to achieve a number of tasks which have no classical counterparts. They include perfectly secure communication, exponential speedup of some computations, and so on. Despite the fruitful results, quantum information processing is very difficult to be realized with a physical system due to the sensitivity of quantum states and quantum operations.
In this dissertation, quantum information processing is briefly introduced, and systems of cavity-trapped single atoms are considered as candidates for physical realization of it. Especially, various single photon input-output processes in the atom-cavity system are presented, and it is shown that they can serve as the essential ingredients for various modes of quantum information processing, such as for conversion and controlled unitary operation between an atomic qubit and a photonic qubit. In that context, new schemes for quantum teleportation of atomic states and for quantum gates between distant atomic qubits are proposed and analyzed both theoretically and numerically concerning various physical and experimental aspects.