Recent work has predicted that quenched near-integrable systems can exhibit dynamics associated with thermal, quantum, or purely non-equilibrium phase transitions, depending on the initial state . Using a trapped-ion quantum simulator with intrinsic long-range interactions, we investigate collective non-equilibrium properties of critical fluctuations after quantum quenches. In particular, we probe the scaling behavior of fluctuations near the critical point of the ground-state disorder-to-order phase transition, after single and double quenches of the transverse field in a long-range Ising Hamiltonian. With system sizes of up to 50 ions, we show that both the post-quench fluctuation magnitude and dynamics scale with system size with distinct critical exponents, characterizing the type of phase transition. Furthermore we demonstrate that the critical exponents after a single and a double quenches are different and correspond to effectively thermal and truly non-equilibrium behavior, respectively. Our results demonstrate the ability of quantum simulators to explore universal scaling beyond the equilibrium context.
 Paraj Titum and Mohammad F. Maghrebi, Phys. Rev. Lett. 125, 040602 (2020)
(Pizza and refreshments will be served after the talk.)