Universality in the Collective Behavior of Open Quantum Systems - Ana Asenjo Garcia

In this seminar, Ana Asenjo Garcia discusses emergent collective behavior in open quantum systems, where dissipation and fluctuations, typically seen as detrimental, can be harnessed to generate order. She begins by contrasting the conventional view of isolation for quantum coherence with examples of order emerging in out-of-equilibrium systems, such as chemical reactions and firefly synchronization. The talk focuses on quantum radiative systems like atoms, where vacuum fluctuations mediate interactions. She introduces the theoretical framework using Lindblad master equations and Green’s functions to describe collective decay. The presentation is structured along a complexity axis: first, single-excitation physics in atomic arrays, where dark and bright states enable quantum dielectric behavior like waveguides and mirrors; second, the limit of full inversion leading to Dicke superradiance, a burst of light scaling as N^2, now observed in extended atomic arrays; and third, the intermediate regime, where she presents her recent work on universal scaling laws for correlated decay in Markovian quantum systems. These scaling laws have implications for metrology, quantum computing, and understanding out-of-equilibrium phase transitions. The talk concludes with experimentally relevant examples where many-body decay offers new control mechanisms.