Atomic systems entangled state detection

In this section we discuss problems that could be involved in any attempt to detect an internal entangled state of two coupled atoms in free space. Beige et al. [34] have proposed a scheme, based on the quantum Zeno effect, to observe a decoherence-free state in a system of two 3-level atoms located inside an optical cavity. Here, we discuss possible schemes to detect entangled states of two 2-level atoms in free space. 

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