Entanglement between macroscopically populated states can easily be created
by combining a single photon and a bright coherent state on a beam-splitter.
Motivated by the simplicity of this technique, we report on a method using
displacement operations in the phase space and basic photon detections to
reveal such an entanglement. We demonstrate through preliminary experimental
results, that this eminently feasible approach provides an attractive way for
exploring entanglement at various scales, ranging from one to a thousand
photons. This offers an instructive viewpoint to gain insight into the reasons
that make it hard to observe quantum features in our macroscopic world.Comment: 6 pages, 10 figures. v2: Updated version. The corresponding
experiment is reported in arXiv:1212.3710. See also arXiv:1306.084
