Spatial correlations and entanglement in a hybrid system of N fermion pairs with harmonic interaction

Abstract

Using the Moshinsky model, we analyze the spatial correlation and the entanglement of the ground state across different bipartitions of a system composed by N pairs of harmonically confined fermions of two different interacting species. We find that in the strongly attractive regime fermions tend to localize within a confined region, while Pauli exclusion induces a spatial repulsion among identical particles. Conversely, in the strongly repulsive regime, the system exhibits phase separation into two spatially distinct domains. We propose a suitably designed entanglement measure that takes into account the (in)distinguishable nature of the particles, so as to guarantee that only quantum correlations beyond exchange or Slater correlations contribute to the entanglement. Our findings reveal how entanglement varies across different bipartitions, influenced by both the number of pairs and the interaction strength. The obtained entanglement between distinguishable species increases with both N and the interaction strength, whereas the entanglement between subsystems of which at least one contains particles of both species decreases with N, suggesting a screening effect that weakens effective interactions among parties of the same kind. Our results sheds light on the intricate interplay between particle statistics and entanglement dynamics in composite quantum systems, and provides insights into the fundamental quantum correlations in fermionic systems.