EPR steering in symmetrical Gaussian states

TL;DR

This paper investigates quantum EPR steering in symmetric Gaussian states, demonstrating that non-Gaussian measurements can outperform Gaussian ones and highlighting the potential for asymmetric measurement setups to reveal steering more effectively.

Contribution

It introduces the use of non-Gaussian measurements to enhance and optimize the detection of EPR steering in symmetric Gaussian states, surpassing Gaussian measurement capabilities.

Findings

Non-Gaussian measurements outperform Gaussian measurements in revealing steering.

Steering is possible regardless of purity with sufficient quadrature variance compression.

Asymmetric measurement setups can be optimal for detecting steering.

Abstract

We have explored quantum Einstein-Podolsky-Rosen steering in symmetric two-mode Gaussian states using Gaussian and non-Gaussian measurements. For Gaussian measurements, we show that steering between the output modes of a symmetric beamsplitter is possible regardless of purity when a threshold input-state quadrature variance compression is achieved. Using the non-Gaussian operators introduced in [1] we show that non-Gaussian measurements can outperform Gaussian measurements for symmetrical states. We also analyze the possibility of asymmetric measurements setups made possible by non-Gaussian measurements and provide examples where such asymmetry is optimal for revealing steering. [1] Ji, SW., Lee, J., Park, J. et al. Quantum steering of Gaussian states via non-Gaussian measurements. Sci Rep 6, 29729 (2016). https://doi.org/10.1038/srep29729