2025/10/20 by Cătălin Paşcu Moca, Moca, Cătălin Paşcu, Doru Sticlet +3 · 1 citation
Physics and Astronomy · #Quantum Mechanics and Non-Hermitian Physics #Quantum many-body systems #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2510.17248
We investigate non-stabilizerness, also known as ``magic,'' to understand criticality and exceptional points in non-Hermitian quantum many-body systems. Our focus is on parity-time (PT) symmetric spin chains, specifically the non-Hermitian transverse-field Ising and XX models. We calculate stabilizer Rényi entropies in their ground states using non-Hermitian matrix product state methods. Our findings show that magic exhibits unique and model-specific signs of phase transitions. In the Ising chain, it peaks along the regular Hermitian-like critical line but disappears across exceptional points. In contrast, in the XX chain, it reaches its maximum at the exceptional line where PT symmetry is broken. Finite-size scaling reveals that these effects become more pronounced with larger systems, highlighting non-stabilizerness as a sensitive marker for both quantum criticality and non-Hermitian spectral degeneracies. We also investigate magic in momentum space for the XX model analytically and find that is reaches a minimum around exceptional points. Our results indicate that magic takes extremal values at the exceptional points and serves as a valuable tool for examining complexity, criticality, and symmetry breaking in non-Hermitian quantum matter.