2026/03/23 by Bikashkali Midya · 1 voice
Physics and Astronomy · #quant-ph #cond-mat.str-el #math-ph
paper · pdf · doi:10.1063/5.0322785
arxiv published 2026/03/23 · arxiv updated 2026/04/08
Theoretical analysis of a prototypical two-qubit effective non-Hermitian system characterized by asymmetric Heisenberg XY interactions in the absence of external magnetic fields demonstrates that maximal bipartite entanglement and quantum phase transitions can be induced exclusively through non-Hermiticity. At thermal equilibrium as T→ 0, the system attains maximal entanglement C=1 for values of the non-Hermiticity parameter greater than a critical value γ>γc=J√((1-δ2)), where J denotes the exchange interaction and δ represents the anisotropy of the system; conversely, for γ< γc, entanglement is nonmaximal and given by C = √((1 - (γ/J)2)). The entanglement undergoes a discontinuous transition to zero precisely at γ= γc. This phase transition originates from the closing of the energy gap at a non-Hermiticity-driven ground state degeneracy, which is fundamentally different from an exceptional point. This work suggests the use of singular-value-decomposition generalized density matrix for the computation of entanglement in bi-orthogonal systems.