Two-mode squeezed states as Schrödinger cat-like states

In recent years, there has been an increased interest in the generation of superposition of coherent states with opposite phases, the so-called photonic Schrödinger-cat states.These experiments are very challenging and so far, cats involving small photon numbers only have been implemented.Here, we propose to consider two-mode squeezed states as examples of a Schrödinger-cat-like state.In particular, we are interested in several criteria aiming to identify quantum states that are macroscopic superpositions in a more general sense.We show how these criteria can be extended to continuous variable entangled states.We apply them to various squeezed states, argue that two-mode squeezed vacuum states belong to a class of general Schrödinger-cat states and compare the size of states obtained in several experiments.Our results not only promote two-mode squeezed states for exploring quantum effects at the macroscopic level but also provide direct measures to evaluate their usefulness for quantum metrology.