General Rules Governing the Dynamical Encircling of an Arbitrary Number of Exceptional Points

Yu, Feng; Zhang, Xu-Lin; Tian, Zhen‐Nan; Chen, Qi‐Dai; Sun, Hong‐Bo

doi:10.1103/physrevlett.127.253901

Cited by 31 publications

(22 citation statements)

References 40 publications

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“…These tunable losses can be realized in potential experiment by judiciously introducing scatters inside the waveguide. [34] The refractive index of lossless waveguides 1 and 3 as well as lossy waveguides 2 and 4 is 1.504, while the substrate has a refractive index of 1.5. This structure can be achieved via utilizing femtosecond laser direct writing techniques in potential experiments.…”

Section: Theoretical Analysis and Numerical Results Of Encirclement P...mentioning

confidence: 99%

“…[21,22,31] The overall chiral mechanism of dynamically encircling an EP is unraveled and analyzed theoretically through confluent hypergeometric functions in a two-level non-Hermitian system, [4,33] and successfully demonstrated in various experiments by encircling EPs. [4,5,[25][26][27][28][29][30]34] One might think that enclosing the EP is a prerequisite for the chiral dynamics. However, a recent experiment makes a breakthrough that the chiral feature is still preserved when encircling the EP's proximity, namely, without encircling an EP.…”

Section: Introductionmentioning

confidence: 99%

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Proximity‐Encirclement of Multiple Exceptional Points in Non‐Hermitian Photonic Waveguides

Shi

Guo

2023

Annalen der Physik

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Conventionally, dynamical encirclement of exceptional points in non‐Hermitian systems is known to manifest a counterintuitive chiral state conversion. However, the prerequisite of such traits enclosing an exceptional point is broken when only encircling its proximity, preserving a still chiral switching. Research on the proximity‐encirclement in multistate systems is lacking. In this paper, a photonic‐waveguide‐array non‐Hermitian system is proposed to investigate the dynamics by encircling two exceptional points or their proximity. A series of encircling trajectories defined by the parametric equations are designed to steer the evolution of photonic modes in waveguides. The wave propagating along the waveguides is also simulated to capture this non‐Hermitian physics. The chiral behavior in proximity‐encirclement contrasts with the familiar encirclement of one exceptional point and exhibits the unexpected occurrence of nonadiabatic transitions. Furthermore, if two exceptional points are sufficiently encircled, the system will evolve to a stable final state earlier, as a symbol of the occurrence of the nonadiabatic transition. Such novel chiral conversion is maintained only if the encircling trajectories are located at adequate proximity.

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Section: Theoretical Analysis and Numerical Results Of Encirclement P...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proximity‐Encirclement of Multiple Exceptional Points in Non‐Hermitian Photonic Waveguides

Shi

Guo

2023

Annalen der Physik

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“…Therefore, the mode‐switching devices, requiring a small footprint, can be developed in the non‐Hermitian regime. Such dynamics in encircling EPs are expected to extend to non‐Hermitian waveguide arrays with more complex and interesting topology, [ 139 ] holding great promise for developing wideband MCs with both a small footprint and robustness against the structure perturbation.…”

Section: Topological Waveguide Arrays Toward Applicationsmentioning

confidence: 99%

Topological Photonic States in Waveguide Arrays

Kang

Wei

Zhang

et al. 2022

Advanced Physics Research

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Topological photonics, accompanied by the ability to manipulate light, has emerged as a rapidly growing field of research. More platforms for displaying novel topological photonic states are being explored, thus offering efficient strategies for the realization of robust photonic devices. Optical waveguide arrays, described as a (n+1)‐dimensional system, are ideal platforms for studying topological photonics because of the characteristic that can exhibit light dynamics. Here, this work reviews the experimental implementations of the various topological phases in the optical waveguide arrays, and specifically discusses novel physical phenomena arising from the combination of topology with non‐Hermitianity and nonlinearity. It is believed that topological waveguide arrays provide powerful support for enriching topological physics and promoting the development of topological photonic integrated devices.

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“…More recently, much effort is put on studying the behavior of modes while encircling high-order or multiple EPs in a parameter space of multimode systems. Indeed, the presence of high-order or multiple low-order EPs in a system spectrum, along with the non-Hermitian breakdown of adiabaticity, can impose a substantial difficulty to manipulate the mode-switching behavior on demand 52 , 63 , 64 . That is, a system may end up only in a few states out of many regardless of the encircling direction and winding number.…”

Section: Introductionmentioning

confidence: 99%

Dynamically crossing diabolic points while encircling exceptional curves: A programmable symmetric-asymmetric multimode switch

et al. 2023

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Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects with no counterparts in Hermitian systems. For instance, in a two-mode photonic system, by dynamically winding around an exceptional point (EP) a controlled asymmetric-symmetric mode switching can be realized. That is, the system can either end up in one of its eigenstates, regardless of the initial eigenmode, or it can switch between the two states on demand, by simply controlling the winding direction. However, for multimode systems with higher-order EPs or multiple low-order EPs, the situation can be more involved, and the ability to control asymmetric-symmetric mode switching can be impeded, due to the breakdown of adiabaticity. Here we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. We consider a four-mode $${{{{{{{\mathcal{PT}}}}}}}}$$ PT -symmetric bosonic system as a platform for experimental realization of such a multimode switch. Our work provides alternative routes for light manipulations in non-Hermitian photonic setups.

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General Rules Governing the Dynamical Encircling of an Arbitrary Number of Exceptional Points

Cited by 31 publications

References 40 publications

Proximity‐Encirclement of Multiple Exceptional Points in Non‐Hermitian Photonic Waveguides

Proximity‐Encirclement of Multiple Exceptional Points in Non‐Hermitian Photonic Waveguides

Topological Photonic States in Waveguide Arrays

Dynamically crossing diabolic points while encircling exceptional curves: A programmable symmetric-asymmetric multimode switch

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