Article
Physics, Multidisciplinary
Kai Zhang, Chen Fang, Zhesen Yang
Summary: In this study, the concept of dynamical degeneracy splitting is introduced to explain the anisotropic decay behaviors in non-Hermitian systems. It is shown that systems with dynamical degeneracy splitting exhibit frequency-resolved non-Hermitian skin effect and anomalous behavior in Green's function, resulting in uneven broadening in spectral function and anomalous scattering. The directional invisibility based on wave packet dynamics is proposed to investigate the geometry-dependent skin effect in higher dimensions. This work provides a guiding principle for exploring novel physical phenomena arising from the non-Hermitian skin effect.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Yongxu Fu, Shaolong Wan
Summary: We developed a general theory of one-dimensional non-Hermitian systems and analyzed the band degeneracy and defectiveness of two typical models. Additionally, we discovered the existence of infernal points in one-dimensional non-Hermitian systems and extended them to infernal knots in four-dimensional systems.
Article
Materials Science, Multidisciplinary
Stefano Longhi, Ermanno Pinotti
Summary: Controlling wave scattering in complex media is important in various fields of classical and quantum physics. Recent research has focused on scattering engineering in non-Hermitian systems, leading to the discovery of new classes of non-Hermitian potentials with unique scattering properties. However, wave scattering in lattice systems has distinct features due to the discrete translational invariance, and this study demonstrates the synthesis of time-dependent non-Hermitian scattering potentials in a Hermitian single-band lattice, which are fully invisible due to the limited energy bandwidth of the lattice.
Article
Optics
Juan Kang, Qinglong Zhang, Ruishan Wei, Jianrong Qiu, Zhongmin Yang, Guoping Dong
Summary: Introducing non-Hermiticity in finite systems is an effective strategy to enhance the localization of higher-order corner states, offering a new avenue for designing compact devices.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
M. Iskin
Summary: In this study, we investigate the phase diagram of the BCS-BEC evolution, finding a reentrant superfluid transition as inelasticity increases. The transition, with exception of strongly inelastic regimes, is mainly governed by exceptional points.
Article
Materials Science, Multidisciplinary
Carlos Ortega-Taberner, Maria Hermanns
Summary: Recent years have seen a growing interest in exploring topological features in non-Hermitian systems and the fate of topology at critical points. It has been observed that both systems share certain topological features, such as half-integer quantized winding numbers and similar entanglement spectra. This study shows the equivalence of topological invariants in critical systems with non-Hermitian point-gap phases and also demonstrates the same topological features in their entanglement spectra. This correspondence may contribute to a deeper understanding of non-Hermitian systems and critical systems.
Article
Optics
Shaolin Ke, Wanting Wen, Dong Zhao, Yang Wang
Summary: The non-Hermitian skin effect (NHSE) reveals unprecedented topological physics by collapsing bulk modes to open boundaries as skin modes. Achieving this effect in photonic waveguides has been challenging due to the difficulty of establishing non-Hermitian asymmetric couplings. In this study, NHSE in photonic waveguide arrays is investigated via Floquet engineering, creating an artificial gauge field (AGF) that interacts with on-site dissipation, resulting in NHSE.
Article
Optics
Federico Roccati, Salvatore Lorenzo, Giuseppe Calajo, G. Massimo Palma, Angelo Carollo, Francesco Ciccarello
Summary: Photon-mediated interaction between quantum emitters is an emerging field in quantum optics. Non-Hermitian physics, particularly in photonic lattices, challenges conventional theories and allows access to new physics. The study reveals that structured losses in the field can lead to exotic emission properties. Photons can mediate dissipative, fully non-reciprocal interactions between emitters, with the range depending on the loss rate.
Article
Materials Science, Multidisciplinary
W. B. Rui, Y. X. Zhao, Z. D. Wang
Summary: The study reveals that the complex energy bands of non-Hermitian systems can braid in momentum space even in one dimension, providing a foundation for Hermitian topological physics with chiral symmetry. A new elegant identity is derived, equating the linking number between the knots of braiding non-Hermitian bands and the zero-energy loop to the topological invariant of chiral-symmetric topological phases. Furthermore, an exotic class of phase transitions arising from the critical point transforming different knot structures of the non-Hermitian braiding is discovered, which is not included in conventional Hermitian topological phase transition theory.
Article
Physics, Multidisciplinary
Ruizhe Shen, Ching Hua Lee
Summary: This study extends the notion of the non-Hermitian skin effect to the regime dominated by many-body interactions and reveals the emergence of a family of skin cluster states. These cluster states, which originate from asymmetric correlated hoppings on a lattice, have translation invariant characteristics and may be of significant interest in modern many-body systems.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Multidisciplinary
Yanting Wu, Jingwen Zou, Chuang Jiang, Xiaohong Li, Shaolin Ke
Summary: This study proposes a method to achieve the direction-dependent non-Hermitian skin effect (NHSE) in a photonic waveguide array through spatially complex modulation. By utilizing complex modulation to induce anisotropic coupling between symmetric and anti-symmetric modes in multimode waveguides, and matching the refractive index of adjacent waveguides, the non-Hermitian Su-Schrieffer-Heeger (SSH) lattice supporting NHSE is realized. The highly unidirectional anisotropic coupling allows mode conversion from antisymmetric modes to symmetric modes only in the forward direction, providing a potential platform for investigating NHSE on photonic chips and finding applications in non-magnetic unidirectional devices.
FRONTIERS IN PHYSICS
(2022)
Article
Multidisciplinary Sciences
Shuo Liu, Ruiwen Shao, Shaojie Ma, Lei Zhang, Oubo You, Haotian Wu, Yuan Jiang Xiang, Tie Jun Cui, Shuang Zhang
Summary: The conventional bulk-boundary correspondence fails in certain non-Hermitian systems with broken reciprocity, while a non-Bloch bulk-boundary condition based on a non-Bloch winding number can accurately predict the number of topological edge states.
Article
Physics, Multidisciplinary
Chenxiao Dong, Zhesen Yang, Jinfeng Zeng, Jiangping Hu
Summary: In this study, we propose a new type of non-unitary discrete-time quantum walk system that demonstrates the non-Hermitian dynamical phenomenon, including the dynamical chiral phenomenon, the funneling phenomenon on the domain wall, and the anomalous reflection on the phase impurity. Furthermore, we design quantum circuit experiments and numerically simulate them with quantum noises to verify the robustness of the non-Hermitian dynamical phenomenon on noisy intermediate-scale quantum devices. Our work paves the way for implementing the non-Hermitian dynamical phenomenon on quantum circuits.
Article
Physics, Multidisciplinary
Victor Atanasov, Rossen Dandoloff, Avadh Saxena
Summary: The study investigates the properties of a static wormhole as a waveguide and determines the conditions for a quantum particle to fully transmit through the wormhole waveguide. It is found that the waveguide is transparent when the quantum particle's angular momentum is 0.
Article
Optics
Youngsun Choi, Yu Sung Choi, Seok Ho Song, Kyungsik Yu, Nimrod Moiseyev, Jae Woong Yoon
Summary: Interferometers and resonant cavities are commonly used in signal processing systems, but their limitations in performance metrics hinder data-processing capabilities. This study proposes a novel wave-modulation mechanism based on non-Hermitian dynamics near an exceptional point (EP) singularity. The proposed modulator bypasses the EP through adiabatic processes, allowing selection of different final states with a very small trigger signal. It does not rely on interference or resonance effects and can be implemented in integrated optical circuits.
LASER & PHOTONICS REVIEWS
(2023)
