2025/03/19 by Márton Mestyán, Mestyán, Márton, Balázs Pozsgay +1 · 2 citations
Physics and Astronomy · #FOS: Physical sciences #Quantum Physics (quant-ph) #Quantum many-body systems #Statistical Mechanics (cond-mat.stat-mech)
paper · pdf · doi:10.48550/arxiv.2503.15640
openalex publication_date 2025/03/19 · openalex created_date 2025/10/17 · openalex updated_date 2026/07/31
It has been observed recently that various spin chain Hamiltonians admit special zero energy "crosscap" eigenstates. These states are made up of maximally entangled Bell pairs prepared on antipodal sites of a periodic chain. We generalize the states by allowing the antipodal pairs to have non-maximal, tunable entanglement. We give sufficient conditions for such states to be exact zero energy eigenstates of a local Hamiltonian. The conditions are naturally satisfied in many models which have a global U(1) symmetry. These models include well known integrable models such as the XX model, the Bariev model, the folded XXZ model, and also a variety of non-integrable models. Using the zero-energy crosscap states we also derive a family of exact zero modes with sub-volume law entanglement.