Probabilistic simulation of mesoscopic “Schrödinger cat” states

•We simulate mesoscopic quantum paradoxes probabilistically.•Our results show Bell violations with up to 60 spins.•This is a counter-example to an argument of Feynman, who thought it was not possible.•The time taken varies strongly with the order of correlation computed.•Our results demonstrate an exponential speed-up compared to experiment.

We carry out probabilistic phase-space sampling of mesoscopic Schrödinger cat quantum states, demonstrating multipartite Bell violations for up to 60 qubits. We use states similar to those generated in photonic and ion-trap experiments. These results show that mesoscopic quantum superpositions are directly accessible to probabilistic sampling, and we analyze the properties of sampling errors. We also demonstrate dynamical simulation of super-decoherence in ion traps. Our computer simulations can be either exponentially faster or slower than experiment, depending on the correlations measured.