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We derive spin squeezing inequalities that generalize the concept of the spin squeezing parameter and provide necessary and sufficient conditions for genuine 2-, or 3-qubit entanglement for symmetric states, and sufficient condition for N-qubit states. Our inequalities have a clear physical interpretation as entanglement witnesses, can be easily measured, and are given by complex but elementary expressions.
Korbicz et al. (Wed,) studied this question.