Berlin 2024 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 69: Nonequilibrium Quantum Systems II (joint session TT/DY)
TT 69.2: Vortrag
Donnerstag, 21. März 2024, 09:45–10:00, H 3025
Cluster Truncated Wigner Approximation: Long-range bond disordered interacting spin-1/2 models — Adrian Braemer1, •Javad Vahedi1,2, and Martin Gärttner1,2 — 1Physikalisches Institut, Heidelberg, Germany — 2Friedrich-Schiller-University, Jena, Germany
Phase-space methods, like Truncated Wigner Approximation (TWA), effectively simulate quantum system dynamics near classical limits by simplifying complexity and preserving initial noise information. However, TWA has limitations in finite times and classical/non-interacting scenarios. For strongly interacting systems far from the classical limit, conventional methods may provide unreliable approximations. The Cluster Truncated Wigner Approximation (cTWA) is an alternative approach introducing additional degrees of freedom to represent correlations independently, using classical equations of motion with initial conditions sampled from Gaussian distributions [1].
Our investigation focuses on quench dynamics in a spin chain with long-range interactions and disordered couplings[2]. Initializing the system in a Néel state, we compute dynamical observables, such as the staggered magnetization and Renyi entropy S_2 for a two-spin subsystem, using cTWA with different choices for the clustering and compare these to results from exact diagonalization. We find that a clustering strategy inspired by real-space renormalisation group argument matches the exact dynamics almost perfectly for a wide range of both interaction range and disorder strength.
Keywords: spin-1/2 chains; Cluster TWA; bound disorder; Long-range