Loophole-free test of quantum non-locality using high-efficiency homodyne detectors

Abstract

We provide a detailed analysis of the recently proposed setup for a loophole-free test of Bell inequality using conditionally generated non-Gaussian states of light and balanced homodyning. In the proposed scheme, a two-mode squeezed vacuum state is de-gaussified by subtracting a single photon from each mode with the use of an unbalanced beam splitter and a standard low-efficiency single-photon detector. We thoroughly discuss the dependence of the achievable Bell violation on the various relevant experimental parameters such as the detector efficiencies, the electronic noise and the mixedness of the initial Gaussian state. We also consider several alternative schemes involving squeezed states, linear optical elements, conditional photon subtraction and homodyne detection.