Title:	Hierarchy of degenerate stationary states in a boundary-driven dipole-conserving spin chain
Authors:	Srivastava, Apoorv Dutta, Shovan
Keywords:	Cellular Automata Conserved Charges Ergodicity Quantum spin Chains
Issue Date:	27-Mar-2025
Publisher:	SciPost Physics
Citation:	SciPost Physics , 2025, Vol. 18(3), AR No. 111
Abstract:	Kinetically constrained spin chains serve as a prototype for structured ergodicity breaking in isolated quantum systems. We show that such a system exhibits a hierarchy of degenerate steady states when driven by incoherent pump and loss at the boundary. By tuning the relative pump and loss and how local the constraints are, one can stabilize mixed steady states, noiseless subsystems, and various decoherence-free subspaces, all of which preserve large amounts of information. We also find that a dipole-conserving bulk suppresses current in steady state. These exact results based on the flow in Hilbert space hold regardless of the specific Hamiltonian or drive mechanism. Our findings show that a competition of kinetic constraints and local drives can induce different forms of ergodicity breaking in open systems, which should be accessible in quantum simulators.
Description:	Open Access. Also available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/8645
ISSN:	2542-4653.
Alternative Location:	https://doi.org/10.48550/arXiv.2411.03309 http://doi.org/10.21468/SciPostPhys.18.3.111
Copyright:	2025 A. Srivastava and S. Dutta.
Appears in Collections:	Research Papers (TP)

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