Equivalence of classicality and separability based on P phasespace representation of symmetric multiqubit states
Classical and quantum world views differ in peculiar ways. Understanding decisive quantum featuresfor which no classical explanation existand their interrelations is of foundational interest. Moreover, recognizing non-classical features carries practical significance in information processing tasks as it offers insights as to why quantum protocols work better than their classical counterparts. We focus here on two celebrated notions of non-classicality viz., negativity of P phasespace representation and entanglement in symmetric multiqubit systems. We prove that they imply each other.
separability symmetric multiqubit states non-classicality quantum entanglement phase space representation