Quantifying identical-particle entanglement

Indistinguishability of particles is a counterintuitive and highly non-classical feature of quantum systems which has proven challenging to relate to standard distinguishable-particle entanglement. Inter-particle entanglement of bosons and fermions, however, plays an important role in systems with particle number superselection rules, such as atom interferometers and cold atom systems. We introduce an entanglement measure aimed at quantifying inter-particle correlations in systems with a given symmetry with respect to particle exchange. Our formalism may be generalised and applied to the quantification of resources in a broad class of quantum information tasks.