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The fermionic Hubbard model (FHM)[1], despite its simple form, captures essential features of strongly correlated electron physics. Ultracold fermions in optical lattices[2, 3] provide a clean and well-controlled platform for simulating…

It is known that many-body correlations qualitatively modify the properties of a one-dimensional metal. However, for a quasi-one-dimensional metal these correlations are suppressed, at least partially. We study conditions under which the…

Strongly Correlated Electrons · Physics 2012-11-15 A. V. Rozhkov

Spin-charge separation (SCS) is a striking manifestation of strong correlations in low-dimensional quantum systems, whereby a fermion splits into separate spin and charge excitations that travel at different speeds. Here, we demonstrate…

Strongly Correlated Electrons · Physics 2020-11-11 Hongmin Gao , Jonathan R. Coulthard , Dieter Jaksch , Jordi Mur-Petit

Eigenmode coalescence imparts remarkable properties to non-hermitian time evolution, culminating in a purely non-hermitian spectral degeneracy known as an exceptional point (EP). Here, we revisit time evolution at the EP and classify…

Quantum Physics · Physics 2021-11-10 Aleksi Bossart , Romain Fleury

The physics of topological singularities, namely exceptional points (EPs), has been a key to wide range of intriguing and unique physical effects in non-Hermitian systems. In this context, the mutual interactions among four coupled states…

Optics · Physics 2020-01-01 Sayan Bhattacherjee , Harsh K. Gandhi , Arnab Laha , Somnath Ghosh

We explore the topological properties of non-Hermitian nodal-link semimetals with dissipative cold atoms in a three-dimensional optical lattice. We construct a two-band continuum model in three dimensions with a spin-dependent gain and…

Mesoscale and Nanoscale Physics · Physics 2020-08-12 Peng He , Jia-Hao Fu , Dan-Wei Zhang , Shi-Liang Zhu

Motivated by the structure of the Swanson oscillator which is a well-known example of a non-Hermitian quantum system consisting of a general representation of a quadratic Hamiltonian, we propose a fermionic extension of such a scheme which…

Quantum Physics · Physics 2024-09-05 Akash Sinha , Aritra Ghosh , Bijan Bagchi

Exceptional points, at which two or more eigenfunctions of a Hamiltonian coalesce, occur in non-Hermitian systems and lead to surprising physical effects. In particular, the behaviour of a system under parameter variation can differ…

Quantum Physics · Physics 2019-12-04 Bradley Longstaff , Eva-Maria Graefe

The most intriguing properties of non-Hermitian systems are found near the exceptional points (EPs) at which the Hamiltonian matrix becomes defective. Due to the complex topological structure of the energy Riemann surfaces close to an EP…

Classical Physics · Physics 2018-06-19 Xu-Lin Zhang , Shubo Wang , Bo Hou , C. T. Chan

Non-Hermitian systems have attracted significant interest because of their intriguing and useful properties, including exceptional points (EPs), where eigenvalues and the corresponding eigenstates of non-Hermitian operators become…

Quantum Physics · Physics 2025-03-28 Hamed Ghaemi-Dizicheh , Shahram Dehdashti , Andreas Hanke , Ahmed Touhami , Janis Nötzel

Exceptional points (EPs) are degeneracies in open wave systems with coalescence of at least two energy levels and their corresponding eigenstates. In higher dimensions, more complex EP physics not found in two-state systems is observed. We…

Exceptional point (EP) is a spectral singularity in non-Hermitian systems. The passing over the EP leads to a phase transition, which endows the system with unconventional features that find a wide range of applications. However, the need…

Quantum Physics · Physics 2023-04-19 T. T. Sergeev , A. A. Zyablovsky , E. S. Andrianov , Yu. E. Lozovik

Exceptional points in non-Hermitian systems have recently been shown to possess nontrivial topological properties, and to give rise to many exotic physical phenomena. However, most studies thus far have focused on isolated exceptional…

Optics · Physics 2019-02-21 Hengyun Zhou , Jong Yeon Lee , Shang Liu , Bo Zhen

Dramatically different from the Hermitian systems, the conventional Bulk-Boundary Correspondence (BBC) is broken in the non-Hermitian systems. In this article, we use edge entanglement entropy to characterize the topological properties of…

Strongly Correlated Electrons · Physics 2022-02-16 Weitao Chen , Liangtao Peng , Hantao Lu , Xiancong Lu

In non-Hermitian systems, the defective band degeneracies, so-called exceptional points (EPs), can form robust exceptional lines (ELs) in 3D momentum space in the absence of any symmetries. Here, we show that a natural orientation can be…

Optics · Physics 2022-12-13 Ruo-Yang Zhang , Xiaohan Cui , Wen-Jie Chen , Zhao-Qing Zhang , C. T. Chan

We show how 1+1-dimensional fermionic symmetry-protected topological states (SPTs, i.e. nontrivial short-range entangled gapped phases of quantum matter whose boundary exhibits 't Hooft anomaly and whose bulk cannot be deformed into a…

Strongly Correlated Electrons · Physics 2021-02-23 Abhishodh Prakash , Juven Wang

Superconductivity and superfluidity of fermions require, within the BCS theory, matching of the Fermi energies of the two interacting Fermion species. Difference in the number densities of the two species leads either to a normal state, to…

Strongly Correlated Electrons · Physics 2009-11-11 L. M. Jensen , J. Kinnunen , P. Torma

The correspondence between exotic quantum holonomy that occurs in families of Hermitian cycles, and exceptional points (EPs) for non-Hermitian quantum theory is examined in quantum kicked tops. Under a suitable condition, an explicit…

Quantum Physics · Physics 2014-04-09 Atushi Tanaka , Sang Wook Kim , Taksu Cheon

Non-Hermitian (NH) systems provide a fertile platform for quantum technologies, owing in part to their distinct dynamical phases. These systems can be characterized by the preservation or spontaneous breaking of parity-time reversal…

We study spin-fluctuation-mediated superconductivity in the one-band Hubbard model. Higher order effective interactions in $U$ give rise to a superconducting instability which is very sensitive to changes in the Fermi surface topology…

Superconductivity · Physics 2016-09-07 Andreas Kreisel , Astrid T. Roemer , Peter J. Hirschfeld , Brian M. Andersen