In this thesis, we study several dynamical aspects of the interaction between a two-level atom and a single-mode quantized field in a coherent state or in a superposed coherent state, and show that a nearly complete teleportation of a superposed coherent state is possible by using the interaction of the field with a two-level atom as an approximated phase-flip operation.
Atomic population inversion shows the well known `collapse and revival of Rabi oscillation' when the field is in a coherent state. Population trapping occurs when the atomic state is prepared in one of two semiclassical dressed states. The dynamics of this system is dependent on the phase difference between the atomic dipole and the coherent field. The splitting and collision of the Q function in phase space is related to the collapse and revival of Rabi oscillation. The degree of entanglement is minimized at the half of the revival time. At this time, any initial atomic state develops into an `attractor state'
When a two-level atom interacts with a superposed coherent state(known as the Schrodinger cat state), the 1st revival of Rabi oscillation occurs faster than for the standard case of the atom-coherent field interaction, exactly at the half of the standard revival time. The population inversion is independent of the phase difference between the atomic dipole and the coherent state. This independency comes from the lack of the single photon coherence for an even or odd coherent state. The behaviors of the Q function are also related to the atomic dynamics. The faster revival is related to the collision of two peaks coming from different components of a superposed coherent state. The standard revival is related to the collision of two peaks coming from a single component.
The four `quasi-Bell states' constructed from two coherent field states of opposite phases can be discriminated with a probability approaching 1 as the average photon number in the field is increased. The flip operation of the superposition phase in a superposed coherent state can be approximately performed by turning on the interaction between a two-level atom and the field until the time the atomic excitation is reached. By using the phase flip operation as described above, a nearly complete teleportation of a superposed coherent state is possible through a maximally entangled channel.
본 논문에서는 이준위 원자와 결맞음 상태 또는 중첩된 결맞음 상태에 있는 양자화된 단일 모드 복사장 사이의 상호작용에서 여러가지 동역학적 특성들을 살펴본다. 그리고 이준위 원자와 중첩된 결맞음 상태에 있는 복사장 사이의 상호작용을 이용하여 충첩된 결맞음 상태를 거의 완벽하게 양자 원격 이동 시킬 수 있음을 보인다.