Enhanced multipartite quantum correlations by non-Gaussian operations

TL;DR

This paper demonstrates that non-Gaussian photon operations, such as subtraction and addition, can enhance multipartite quantum correlations like nonlocality and entanglement in continuous variable GHZ states, especially in weak squeezing regimes.

Contribution

It shows that photon subtraction and addition can strengthen multipartite quantum correlations, providing practical methods to improve quantum information protocols.

Findings

Photon subtraction on each mode enhances nonlocality in weak squeezing regimes.

Photon addition broadens the parameter range for nonlocality enhancement.

Photon subtraction on two modes improves entanglement measures like Gaussian tangle and teleportation fidelity.

Abstract

We study how conditional photon operations can affect multipartite quantum correlations, specifically nonlocality and entanglement, of the continuous variable GHZ states. We find that the violation of the Mermin-Klyshko inequality revealing the multipartite nonlocality can be made stronger with photon subtraction applied on each mode of the original GHZ states, particularly in a weak squeezing regime. Photon addition applied on local modes also turns out to enhance the degree of multipartite nonlocality in a broad range of parameters. We further investigate the effects of the photon operations on the degree of multipartite entanglement by looking into the Gaussian tangle, the fidelity of teleportation network, and the quadrature correlations. We find that photon subtraction applied on two modes enhances those entanglement characteristics in a practical squeezing regime while there is no improvement made by photon addition.