  Quantum entanglement is a fascinating phenomenon, especially if it is
observed at the macroscopic scale. Importantly, macroscopic quantum
correlations can be revealed only by accurate measurement outcomes and
strategies. Here, we formulate feasible entanglement witnesses for bright
squeezed vacuum in the form of the macroscopically populated polarization
triplet Bell states. Their testing involves efficient photodetection and the
measurement of the Stokes operators variances. We also calculate the measures
of entanglement for these states such as the Schmidt number and the logarithmic
negativity. Our results show that the bright squeezed vacuum degree of
polarization entanglement scales as the mean photon number squared. We analyze
the applicability of an operational analog of the Schmidt number.
