Twisted Rényi negativity as a reliable proxy for mixed-state entanglement in fermionic systems

Characterizing mixed-state entanglement in fermionic quantum matter represents a fundamental challenge at the intersection of condensed matter physics and quantum information. Unlike pure states, mixed states lack a universally accepted and easily computable entanglement measure, a difficulty compounded in fermionic systems by the ambiguity of the partial transpose operation. Here, motivated by the Hermiticity of the partially transposed density matrix and the analytic continuation of the Rényi negativity to logarithmic negativity, we address this puzzle by demonstrating the "twisted" Rényi negativity as a physically consistent proxy for mixed-state entanglement in the Hubbard and spinless [Formula: see text]-[Formula: see text] models. Through large-scale quantum Monte Carlo simulations of these paradigmatic correlated systems, we show that this indicator captures essential physical expectations-including the area law and monotonic thermal suppression-while excluding anomalous behavior present in alternative definitions. Our findings not only provide a robust theoretical framework for quantifying entanglement in strongly correlated electronic systems but also offer a practical tool for experimental detection in rapidly developing platforms, including ultracold atomic gases and programmable quantum simulators.