%AZhu, Bihui%ARey, Ana%ASchachenmayer, Johannes%BJournal Name: New Journal of Physics; Journal Volume: 21; Journal Issue: 8; Related Information: CHORUS Timestamp: 2021-11-18 13:17:50 %D2019%IIOP Publishing %JJournal Name: New Journal of Physics; Journal Volume: 21; Journal Issue: 8; Related Information: CHORUS Timestamp: 2021-11-18 13:17:50 %K %MOSTI ID: 10308369 %PMedium: X %TA generalized phase space approach for solving quantum spin dynamics %XAbstract

Numerical techniques to efficiently model out-of-equilibrium dynamics in interacting quantum many-body systems are key for advancing our capability to harness and understand complex quantum matter. Here we propose a new numerical approach which we refer to as generalized discrete truncated Wigner approximation (GDTWA). It is based on a discrete semi-classical phase space sampling and allows to investigate quantum dynamics in lattice spin systems with arbitraryS ≥ 1/2. We show that the GDTWA can accurately simulate dynamics of large ensembles in arbitrary dimensions. We apply it forS > 1/2 spin-models with dipolar long-range interactions, a scenario arising in recent experiments with magnetic atoms. We show that the method can capture beyond mean-field effects, not only at short times, but it also can correctly reproduce long time quantum-thermalization dynamics. We benchmark the method with exact diagonalization in small systems, with perturbation theory for short times, and with analytical predictions made for models which feature quantum-thermalization at long times. We apply our method to study dynamics in largeS > 1/2 spin-models and compute experimentally accessible observables such as Zeeman level populations, contrast of spin coherence, spin squeezing, and entanglement quantified by single-spin Renyi entropies. We reveal that largeSsystems can feature larger entanglement than correspondingS = 1/2 systems. Our analyses demonstrate that the GDTWA can be a powerful tool for modeling complex spin dynamics in regimes where other state-of-the art numerical methods fail.

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