Quantum entanglement of identical particles by standard information-theoretic notions

TL;DR

This paper introduces a new state-based method for quantifying quantum entanglement of identical particles, addressing previous limitations and linking theoretical insights with experimental observations in ultracold atoms.

Contribution

It presents a novel approach that does not label identical particles, incorporating overlaps, measurements, and particle type to assess entanglement using quantum information concepts.

Findings

Overlaps and particle nature influence entanglement measures.

Bringing particles together acts as an entangling gate.

Supports experimental observations with ultracold atoms.

Abstract

Quantum entanglement of identical particles is essential in quantum information theory. Yet, its correct determination remains an open issue hindering the general understanding and exploitation of many-particle systems. Operator-based methods have been developed that attempt to overcome the issue. We introduce a state-based method which, as second quantization, does not label identical particles and presents conceptual and technical advances compared to the previous ones. It establishes the quantitative role played by arbitrary wave function overlaps, local measurements and particle nature (bosons or fermions) in assessing entanglement by notions commonly used in quantum information theory for distinguishable particles, like partial trace. Our approach furthermore shows that bringing identical particles into the same spatial location functions as an entangling gate, providing fundamental theoretical support to recent experimental observations with ultracold atoms. These results pave the way to set and interpret experiments for utilizing quantum correlations in realistic scenarios where overlap of particles can count, as in Bose-Einstein condensates, quantum dots and biological molecular aggregates.