Erlangen 2018 – scientific programme

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A: Fachverband Atomphysik

A 26: Ultracold Plasmas and Rydberg systems (joint session A/Q)

A 26.4: Talk

Wednesday, March 7, 2018, 14:45–15:00, K 0.011

Epidemic dynamics in open quantum spin systems — Carlos Perez-Espigares¹, •Matteo Marcuzzi¹, Ricardo Gutierrez^1,2, and Igor Lesanovsky¹ — ¹School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK — ²Complex Systems Group, Universidad Rey Juan Carlos, 28933 Móstoles, Madrid, Spain

We derive a simple epidemic spreading process to describe the nonequilibrium dynamics of an open many-body system, motivated by recent experiments realised with strongly-interacting gases of highly-excited (Rydberg) atoms, in which the facilitated excitation of Rydberg states competes with radiative decay in a three-level structure. This is approximately mapped onto a population dynamics model where individuals can be either healthy, infected or immunised, and which displays a continuous phase transition from a regime where the epidemic stops to one where instead it can continue spreading indefinitely. The study of the strongly-dephased (classical) regime displays signatures of this continuous phase transition, whereas a preliminary analysis of the weakly-dephased (quantum) regime suggests a shift to a sequence of discontinuous jumps. We discuss the limitations of our modelling imposed by a more realistic setting of laser-driven Rydberg atoms, with a particular focus on the role of the long-range tails of the interactions.