Fig. 2

Experimental results for the CV two-mode Gaussian entangled state in a lossy channel with transmission efficiency η. a Inverse multi-mode squeezing coefficients (7). The plot shows the squeezing coefficient \(\xi _{A|B}^{ - 2}\) obtained by numerically minimizing in Eq. (7), using the experimentally measured covariance matrices (blue dots) and the theoretical prediction based on the state preparation schemes described in Fig. 1 (blue line). Values above one violate (6) and indicate entanglement. b Gaussian quantum Fisher information entanglement criterion, expressed by the maximum eigenvalue of the matrix on the left-hand side (l.h.s.) of Eq. (4). Positive values violate the separability condition (4). The error bars represent one standard deviation and are obtained from the statistics of the measured data