Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition

TL;DR

This paper demonstrates that applying a coherent superposition of photon subtraction and addition to two-mode squeezed states enhances entanglement, correlations, and teleportation performance, especially in low-squeezing regimes.

Contribution

It introduces a method of using coherent superpositions of photon operations to improve quantum entanglement and related properties in continuous-variable systems.

Findings

Enhanced entanglement and correlations with coherent superposition operations.

Greater improvements in low-squeezing regimes compared to photon subtraction or addition alone.

Optimal operation shifts to photon subtraction in high-squeezing regimes.

Abstract

We investigate how the entanglement properties of a two-mode state can be improved by performing a coherent superposition operation of photon subtraction and addition, proposed by Lee and Nha [Phys. Rev. A 82, 053812 (2010)], on each mode. We show that the degree of entanglement, the EPR-type correlation, and the performance of quantum teleportation can be all enhanced for the output state when the coherent operation is applied to a two-mode squeezed state. The effects of the coherent operation are more prominent than those of the mere photon subtraction and the addition particularly in the small squeezing regime, whereas the optimal operation becomes the photon subtraction in the large-squeezing regime.