Quantum nonlocality and quantum key distribution with the two-mode Gaussian equally squeezed state of continuous-variable systems

Abstract

We propose a scheme for generating the two-mode Gaussian equally squeezed state (GESS) by using the optical method and analyze the entanglement properties of this state by means of the logarithmic negativity. It is shown that such a two-mode GESS contains the same amount of entanglement as the two-mode squeezed vacuum state (TSVS). We investigate quantum nonlocality for this state by using two-mode Wigner function measurement. It is found that the operations of local squeezing and distancing can effectively enhance the degree of quantum nonlocality. We propose a quantum key distribution scheme based on the two-mode GESS, and we show that the proposed scheme is more secure against the partial interception attack strategy than one with Einstein–Podolsky–Rosen (EPR) pairs even though the transmission coefficient of the eavesdropping beam splitter is rather low.