  For systems of identical Bosons, it is necessary to reformulate the notions
of separability and entanglement in algebraic terms shifting the emphasis from
the particle aspect of first quantization to the mode description typical of
second quantization. Within this new framework, we show that, unlike for
systems consisting of distinguishable qubits, negativity is an exhaustive
bipartite entanglement witness for systems with fixed number of Bosons;
further, we investigate the impact of dephasing noise in relation to the use of
such many-body Bosonic systems in metrological applications.
