Freiburg 2024 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 15: Poster I
A 15.11: Poster
Dienstag, 12. März 2024, 17:00–19:00, Tent A
Indication of critical scaling in time during the relaxation of an open quantum system — •Julian Feß1, Ling-Na Wu2, Jens Nettersheim1, Alexander Schnell3, Sabrina Burgardt1, Silvia Hiebel1, Daniel Adam1, André Eckardt3, and Artur Widera1 — 1Department of Physics, RPTU Kaiserslautern, Germany — 2Center for Theoretical Physics and School of Science, Hainan University, Haikou, China — 3Institut für Theoretische Physik, Technische Universität Berlin, Germany
Critical scaling occurs in phase transitions corresponding to the singular behaviour of physical systems in response to continuous control parameters. Recently, dynamical quantum phase transitions and universal scaling have been observed in the non-equilibrium dynamics of isolated quantum systems, with time as the control parameter. However, signatures of such critical phenomena in time in open systems were so far elusive. Here, we present results indicating that critical scaling with respect to time can also occur in open quantum systems. We experimentally measure the relaxation dynamics of the large atomic spin of individual Caesium atoms induced by the dissipative coupling to an ultracold Bose gas. For initial states far from equilibrium, the entropy is found to peak in time, transiently approaching its maximum possible value, before eventually relaxing to its lower equilibrium value. Moreover, a finite-size scaling analysis shows that it corresponds to a critical point in the limit of large system sizes. It is signalled by the divergence of a characteristic length, characterized by critical exponents that are found to be independent of system details.
Keywords: critical scaling; impurity; open system; spin exchange collisions; single atoms