Using an operational definition we quantify the entanglement, $E_P$, between two parties who share an arbitrary pure state of $N$ indistinguishable particles. We show that $E_P\le E_M$, where $E_M$ is the bipartite entanglement calculated from the mode-occupation representation. Unlike $E_M$, $E_P$ is superadditive. For example, $E_P=0$ for any single-particle state, but the state $|1⟩|1⟩$, where both modes are split between the two parties, has $E_P=1/2$. We discuss how this relates to quantum correlations between particles, for both fermions and bosons.

• Received 1 October 2002

DOI:https://doi.org/10.1103/PhysRevLett.91.097902