# Entanglement of macroscopically distinct states of light. (arXiv:1811.01041v3 [quant-ph] UPDATED)

Schr\"odinger's famous Gedankenexperiment has inspired multiple generations

of physicists to think about apparent paradoxes that arise when the logic of

quantum physics is applied to macroscopic objects. The development of quantum

technologies enabled us to produce physical analogues of Schr\"odinger's cats,

such as superpositions of macroscopically distinct states as well as entangled

states of microscopic and macroscopic entities. Here we take one step further

and prepare an optical state which, in Schr\"odinger's language, is equivalent

to a superposition of two cats, one of which is dead and the other alive, but

it is not known in which state each individual cat is. Specifically, the alive

and dead states are, respectively, the displaced single photon and displaced

vacuum (coherent state), with the magnitude of displacement being on a scale of

$10^8$ photons. These two states have significantly different photon statistics

and are therefore macroscopically distinguishable.