Berlin 2024 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 71: Many-Body Quantum Dynamics I (joint session DY/TT)
TT 71.5: Vortrag
Donnerstag, 21. März 2024, 10:30–10:45, A 151
A metronome spin stabilizes time-crystalline dynamics — •Niklas Euler1,2, Adrian Braemer2, and Martin Gärttner1,2 — 1Institute of Condensed Matter Theory and Optics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena, Germany — 2Physikalisches Institut, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
We investigate a disorder-free quantum Ising chain subject to a time-periodic drive that rotates each spin by an angle π(1−єi). In case all spins experience the same deviation є and the system starts from a fully magnetized state, the dynamics is known to be time crystalline: The magnetization exhibits stable, period-doubled oscillations for timescales that grow exponentially with system size. In this work, we study the effect of є differing between the spins. We find that reducing є for a single spin drastically enhances the lifetime of spatial-temporal order, suggesting the name “metronome" spin. Employing perturbative arguments, we explain this observation for initial states with macroscopic bulk magnetization. Furthermore, in the case of random bitstring initial states, we report enhancement of the lifetime of a topological edge mode. Here, we relate the presence of the metronome spin to the suppression of resonant processes. Finally, we discuss an altered geometry in which the metronome spin is not directly part of the chain, making the two described mechanisms clearly distinguishable. Our results illuminate the rich nature of spatially-varying Floquet driving, establishing it as a promising technique for fields like Floquet engineering.
Keywords: Floquet; Out-of-equilibrium; Time crystal; Many-body