Bounds on the entanglement entropy by the number entropy in non-interacting fermionic systems
Bounds on the entanglement entropy by the number entropy in non-interacting fermionic systems
Entanglement in a pure state of a many-body system can be characterized by the R\'enyi entropies $S^{(\alpha)}=\ln\textrm{tr}(\rho^\alpha)/(1-\alpha)$ of the reduced density matrix $\rho$ of a subsystem. These entropies are, however, difficult to access experimentally and can typically be determined for small systems only. Here we show that for free fermionic …