Measurable lower bounds on concurrence

TL;DR

This paper presents a method to derive measurable lower bounds on the concurrence of mixed quantum states, applicable to both bipartite and multipartite systems, improving entanglement detection accuracy.

Contribution

The authors introduce a novel approach to obtain measurable lower bounds on concurrence based on algebraic bounds, enhancing detection of entanglement in mixed states.

Findings

Method detects more entangled states than previous bounds.

Provides sharper lower bounds on concurrence.

Applicable to both bipartite and multipartite states.

Abstract

We derive measurable lower bounds on concurrence of arbitrary mixed states, for both bipartite and multipartite cases. First, we construct measurable lower bonds on the purely algebraic bounds of concurrence [F. Mintert et al. (2004), Phys. Rev. lett., 92, 167902]. Then, using the fact that the sum of the square of the algebraic bounds is a lower bound of the squared concurrence, we sum over our measurable bounds to achieve a measurable lower bound on concurrence. With two typical examples, we show that our method can detect more entangled states and also can give sharper lower bonds than the similar ones.