Rostock 2019 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 56: Quantum Optics III
Q 56.6: Talk
Thursday, March 14, 2019, 15:30–15:45, S Ex 04 E-Tech
Universal relaxation dynamics in a disordered Heisenberg spin system — •Titus Franz1, Adrien Signoles1,2, Renato Ferracini Alves1, Martin Gärttner3, Shannon Whitlock1,4, Gerhard Zürn1, and Matthias Weidemüller1,5 — 1Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany. — 2Institut d’Optique, Palaiseau, France — 3Kirchhof Institut für Physik, Universität Heidelberg, Heidelberg, Germany — 4IPCMS and ISIS, University of Strasbourg and CNRS, Strasbourg, France — 5Shanghai Branch, University of Science and Technology of China, Shanghai 201315, China
The macroscopic nature of many-body systems is drastically changed by the presence of disorder in the medium which induces new phases of matter like Spin glasses or Localization. Using a frozen gas of Rydberg atoms, we study how the interplay between quantum fluctuations and disorder changes the far-from equilibrium dynamics of an isolated Heisenberg XXZ spin system. In this work, we can attribute fully coherent dynamics and a drastic deviation from mean-field predictions to the quantum nature of the system, while disorder leads to a non-exponential relaxation of the magnetization towards a randomized state. We found that the system is characterized by a stretched exponential function with a universal stretched exponent of 0.4, independent of the strength of interactions and disorder. This might indicate that slow dynamics described by stretched exponential decay is a generic feature of disordered quantum spin systems hinting towards a unifying effective theory description.