Symmetry decomposition of negativity of massless free fermions

Understand

We consider the problem of symmetry decomposition of the entanglement negativity in free fermionic systems.

• Rather than performing the standard partial transpose, we use the partial time-reversal transformation which naturally encodes the fermionic statistics.
• The negativity admits a resolution in terms of the charge imbalance between the two subsystems.
• We introduce a normalised version of the imbalance resolved negativity which has the advantage to be an entanglement proxy for each symmetry sector, but may diverge in the limit of pure states for some sectors.