Control of evolutionary atomic system of excited atom by using ideal photonic band-gap model

Abstract

The evolution of two-level atomic system, in which the initial state is excited state, is investigated by adjusting the structural parameters of the dynamic and static ideal photonic band-gap environment reservoir. In a static state (no modulation), we study the effects of half width, center resonant frequency, and specific gravity on the evolution of energy level population. The results show that when the half width or the specific gravity decreases, in the atomic system there happens decoherence, and the energy dissipation to the outside becomes slower. When the center resonant frequency increases, there exists no resonance between the library central resonant frequency and the atom transition frequency, then the attenuation suppression effect occurs, and the time of atomic attenuation to ground state is longer. An actual quantum system is not isolated, so it is inevitable that it interacts with its ambient environment. Owing to the influence of environment, in the system there appears an irreversible quantum decoherence phenomenon. Therefore, how to effectively suppress the decoherence of quantum system becomes an important problem in quantum information science. Linington and Garraway (2008 Phys. Rev. A 77 033831) pointed out that the evolution process of a two-level atom quantum state can be manipulated by a dynamic dissipative environment. So, we use the dynamic cavity environment to control the evolution of spontaneous emission from an excited two-level atom. The dynamic modulation form for the center resonant frequency of the ideal photonic band-gap environment reservoir includes the rectangular single pulse, rectangular periodic pulse, and slow continuous period. Owing to the periodic modulation, the atoms are affected by different environments. On this basis, the influence of dynamic modulation form on the atomic population evolution is discussed. It is found that no matter what form the dynamic modulation is in, the attenuation inhibition in the evolution of atomic system is evident. These conclusions make the idea of using the environmental change to modulate the coherent evolution of atomic system become true.