The Joint Condensed Matter Seminar (JCMS) series is organised by KTH Royal Insitute of Technology, Nordita, and Stockholm University.
On Monday, April 29th, 2024 from 11 am to 12 am we will host a seminar by Tsuneya Yoshida from Kyoto University.
Correlation effects on non-Hermitian skin effects and exceptional points
Recently, it has tuned out that non-Hermitian systems exhibit novel topological phenomena which do not have Hermitian counterparts [1-3]. A representative example is a non-Hermitian skin effect [4] which induces extreme sensitivity of eigenvalues and eigenstates to boundary conditions due to the non-Hermitian topology in the bulk. In particular, under open boundary conditions, most of eigenstates are localized at the edge which are called skin modes. While the non-Hermitian topology of on-interacting cases has extensively studied so far, the non-Hermitian topology of strongly correlated systems has not been sufficiently explored. In this talk, we analyze interplay between strong correlations and non-Hermitian skin effect [5]. Our analysis of a bosonic open quantum system discovers a novel type of non-Hermitian skin effect: the Mott skin effect. In contrast to the ordinary non-Hermitian skin effect of non-interacting systems, the Mott skin effect induces skin modes only in spin degree of freedom. Our numerical simulation also demonstrates that such skin modes induce dynamical spin accumulation while charge distribution remains uniform. If time allows, we also address correlation effects on an exceptional point which is degeneracy of eigenvalues protected by non-Hermitian topology [6]. Our analysis elucidates that correlations may change the topological classification which results in fragility of exceptional points against interactions.
[1] Y. Ashida et al., Adv. Phys. 69, 249 (2021). [2] E. J. Bergholtz et al., Rev. Mod. Phys. (2021). [3] Z. Gong et al., Phys. Rev. X 8, 031079 (2018); K. Kawabata et al., Phys. Rev. X 9, 041015 (2019). [4] N. Okuma et al., Phys. Rev. Lett. 124, 086801 (2020). [5] T. Yoshida et al., arXiv:2309.14111 (2023). [6] T. Yoshida and Y. Hatsugai, Phys. Rev. B 106, 205147 (2022).