Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 65: Poster – Ultra-cold plasmas and Rydberg systems (joint session A/Q)

Q 65.2: Poster

Thursday, March 5, 2026, 17:00–19:00, Philo 1. OG

Hilbert space fragmentation in driven-dephasing Rydberg atom array — •tianyi yan, chunhei leung, and weibin li — School of Physics and Astronomy and Centre for the Mathematics and Theoretical Physics of Quantum Non-equilibrium Systems, University of Nottingham, Nottingham NG7 2RD, United Kingdom

We investigate the onset and mechanism of Hilbert space fragmentation (HSF) in a chain of strongly interacting Rydberg atoms subject to local dephasing. It is found that the emergence of multiple long-lived metastable states is fundamentally tied to HSF of the driven-dephasing Rydberg atom system. We demonstrate that the manifesting HSF is captured by a dephasing PXP model that supports multiple degenerate zero modes. These modes form disconnected, block-diagonal subspaces of maximally mixed states, which consist of many-body spin states sharing the same symmetry. A key result is the identification of the underlying symmetry in the HSF, where conserved quantities in each subspace are defined by the consecutive double excitation addressing operator. Moreover, we show explicitly that the number of the fragmented Hilbert space grows exponentially with the chain length, following a modified Fibonacci sequence. Our work provides insights into many-body dynamics under dynamical constraints and opens avenues for controlling and manipulating HSF in Rydberg atom systems.

Keywords: Rydberg systems; Open quantum systems; Kinetic constraints; Hilbert space fragmentation; Metastable states