Phase decoherence suppression in arbitrary n-level atom in Ξ-configuration with Bang-Bang controls

In this paper, we derive the conditions of maintaining quantum coherence in arbitrary n-level atom in Ξ-configuration with Bang-Bang (BB) controls when the system exists the phase decoherence, the amplitude decoherence and the general decoherence (the amplitude damping and phase damping simultaneously), respectively. On this basis, we propose our BB decoupling scheme to suppress the phase decoherence in arbitrary n-level atom in Ξ-configuration. The corresponding decoupling operators are derived explicitly. At last we design the BB decoupling scheme to suppress phase decoherence for a six-level atom system in Ξ-configuration.