QUROPE Quantum Information Processing and Communication in Europe

Complex systems are often found to exhibit unexpectedly simple scaling laws that can signal new physical regimes or universal relations between otherwise very different systems. Although this provides a powerful tool for characterising systems close to equilibrium, there are only few known examples where scaling behaviour can be found in dynamical settings. Here we demonstrate power-law scaling in a well-controlled quantum spin system driven out of equilibrium. This enables us to reconstruct the non-equilibrium phase diagram of the system and identify dissipation-dominated, driving-dominated and interaction-dominated regimes. The measured scaling laws show signatures of the underlying ground state phase structure, including paramagnetic behaviour, quantum critical behaviour and a magnetic instability towards states with strong spatial correlations. This opens up a new means to study and classify quantum systems out of equilibrium and extends the domain where scale-invariant behaviour can be found.