We explore the eigenvalue statistics of a non-Hermitian version of the Su-Schrieffer-Heeger model, with imaginary on-site potentials and randomly distributed hopping terms. We find that owing to the structure of the Hamiltonian, eigenvalues can be purely real in a certain range of parameters, even in the absence of parity and time-reversal symmetry. As it turns out, in this case of purely real spectrum, the level statistics is that of the Gaussian orthogonal ensemble. This demonstrates a general feature which we clarify that a non-Hermitian Hamiltonian whose eigenvalues are purely real can be mapped to a Hermitian Hamiltonian which inherits the symmetries of the original Hamiltonian. When the spectrum contains imaginary eigenvalues, we show that the density of states (DOS) vanishes at the origin and diverges at the spectral edges on the imaginary axis. We show that the divergence of the DOS originates from the Dyson singularity in chiral-symmetric one-dimensional Hermitian systems and derive analytically the asymptotes of the DOS which is different from that in Hermitian systems.
Bibliographical noteFunding Information:
This collaboration was initiated when the authors met at the International Centre for Theoretical Sciences (ICTS) during a visit for participating in the program “Non-Hermitian Physics–PHHQP XVIII”. We thank Yasuhiro Asano, Roman Riser, and Kousuke Yakubo for helpful discussions. The work of K.M., N.H., and H.O., was supported by KAKENHI (Grants No. JP18J20727, No.JP18H01140, No. JP18K18733, No. JP19K03646, and No. JP19H00658). J.F.'s work was supported by the Israel Science Foundation (ISF) under Grant No. 2040/17.
© 2020 American Physical Society.
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Statistics and Probability
- Condensed Matter Physics