Optimizing confidence in negative-partial-transpose-based entanglement criteria

TL;DR

This paper introduces a statistical framework to optimally select and evaluate negative-partial-transpose-based entanglement criteria, enhancing the reliability of quantum state separability tests under practical measurement conditions.

Contribution

It develops a method to determine the confidence level of NPT-based entanglement criteria considering measurement noise and resource allocation, applicable to various quantum states.

Findings

Framework successfully applied to Gaussian and non-Gaussian states

Improves confidence assessment of entanglement detection

Applicable to a wide range of nonclassicality criteria

Abstract

A key requirement of any separable quantum state is that its density matrix has a positive partial transpose. For continuous bipartite quantum states, violation of this condition may be tested via the hierarchy of negative-partial-transpose (NPT) based entanglement criteria introduced by Shchukin and Vogel [Phys. Rev. Lett. 95, 230502 (2005)]. However, a procedure for selecting the optimal NPT-based criterion is currently lacking. Here, we develop a framework to select the optimal criterion by determining the level of confidence of criteria within the Shchukin and Vogel hierarchy for finite measurement number, environmental noise, and the optimal allocation of measurement resources. To demonstrate the utility of our approach, we apply our statistical framework to prominent example Gaussian and non-Gaussian states, including the two-mode squeezed vacuum state, the quanta-subtracted two-mode squeezed vacuum state, and the two-mode Schr\"odinger-cat state. Beyond bipartite inseparability tests, our framework can be applied to any Hermitian matrix constructed of observable moments and thus can be utilized for a wide variety of other nonclassicality criteria and multi-mode entanglement tests.