An exceptional point switches stability of a thermoacoustic experiment

2021 ◽  
Vol 920 ◽  
Author(s):  
Abdulla Ghani ◽  
Wolfgang Polifke
Keyword(s):  
Exceptional Point

Abstract

scholarly journals Observation of anti-parity-time-symmetry, phase transitions and exceptional points in an optical fibre

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Arik Bergman ◽  
Robert Duggan ◽  
Kavita Sharma ◽  
Moshe Tur ◽  
Avi Zadok ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Brillouin Scattering ◽  
Optical Gain ◽  
Single Mode ◽  
Exceptional Point ◽  
Small Scale ◽  
Time Symmetry ◽  
Topological Features ◽  
Gain And Loss ◽  
Exotic Physics

AbstractThe exotic physics emerging in non-Hermitian systems with balanced distributions of gain and loss has recently drawn a great deal of attention. These systems exhibit phase transitions and exceptional point singularities in their spectra, at which eigen-values and eigen-modes coalesce and the overall dimensionality is reduced. So far, these principles have been implemented at the expense of precise fabrication and tuning requirements, involving tailored nano-structured devices with controlled optical gain and loss. In this work, anti-parity-time symmetric phase transitions and exceptional point singularities are demonstrated in a single strand of single-mode telecommunication fibre, using a setup consisting of off-the-shelf components. Two propagating signals are amplified and coupled through stimulated Brillouin scattering, enabling exquisite control over the interaction-governing non-Hermitian parameters. Singular response to small-scale variations and topological features arising around the exceptional point are experimentally demonstrated with large precision, enabling robustly enhanced response to changes in Brillouin frequency shift.

scholarly journals Biosensing Near the Exceptional Point Based on Resonant Optical Tunneling Effect

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 426
Author(s):  
Yang Liu ◽  
Pengyun Yan ◽  
Feng Liu ◽  
Aoqun Jian ◽  
Shengbo Sang
Keyword(s):  
Exceptional Point ◽  
Tunneling Effect ◽  
Coupled Mode Theory ◽  
Environment Protection ◽  
Label Free ◽  
Liquid Sample ◽  
Water Safety ◽  
Coupled Mode ◽  
Drinking Water Safety ◽  
Optical Tunneling

Inspired by exceptional point (EP) sensing in non-Hermitian systems, in this work, a label-free biosensor for detecting low-concentration analytes is proposed, via a special multilayer structure: a resonant optical tunneling resonator. Due to the square root topology near the exceptional point, a recognized target analyte perturbs the system deviated from the exceptional point, leading to resolvable modes splitting in the transmission spectrum. The performance of the designed sensor is analyzed by the coupled-mode theory and transfer matrix method, separately. Here, the simulation results demonstrate that the obtained sensitivity is 17,120 nm/imaginary part unit of refractive index (IP) and the theoretical detection limit is 4.2 × 10−8 IP (regarding carcinoembryonic antigen (CEA), the minimum detection value is 1.78 ng). Instead of the typical diffusion manner, the liquid sample is loaded by convection, which can considerably improve the efficiency of sample capture and shorten the response time of the sensor. The sketched sensor may find potential application in the fields of biomedical detection, environment protection, and drinking water safety.

scholarly journals Enhanced avionic sensing based on Wigner’s cusp anomalies

2021 ◽  
Vol 7 (23) ◽  
pp. eabg8118
Author(s):  
Rodion Kononchuk ◽  
Joshua Feinberg ◽  
Joseph Knee ◽  
Tsampikos Kottos
Keyword(s):  
Cross Section ◽  
Linear Response ◽  
Nuclear Reactions ◽  
Exceptional Point ◽  
Small Perturbations ◽  
Differential Scattering Cross Section ◽  
Sensing Applications ◽  
Physical Observable ◽  
Resonant Systems ◽  
Square Root Singularity

Typical sensors detect small perturbations by measuring their effects on a physical observable, using a linear response principle (LRP). It turns out that once LRP is abandoned, new opportunities emerge. A prominent example is resonant systems operating near Nth-order exceptional point degeneracies (EPDs) where a small perturbation ε ≪ 1 activates an inherent sublinear response ∼εN≫ε in resonant splitting. Here, we propose an alternative sublinear optomechanical sensing scheme that is rooted in Wigner’s cusp anomalies (WCAs), first discussed in the framework of nuclear reactions: a frequency-dependent square-root singularity of the differential scattering cross section around the energy threshold of a newly opened channel, which we use to amplify small perturbations. WCA hypersensitivity can be applied in a variety of sensing applications, besides optomechanical accelerometry discussed in this paper. Our WCA platforms are compact, do not require a judicious arrangement of active elements (unlike EPD platforms), and, if chosen, can be cavity free.

Observation of plasmonic exceptional point and nano-scale sensing

2020 ◽  
Author(s):  
Abdoulaye Ndao ◽  
Jun-Hee Park ◽  
Liyi Hsu ◽  
Boubacar Kanté
Keyword(s):  
Exceptional Point ◽  
Nano Scale

scholarly journals PT -symmetric waveguide system with evidence of a third-order exceptional point

2017 ◽  
Vol 95 (5) ◽  
Author(s):  
Jan Schnabel ◽  
Holger Cartarius ◽  
Jörg Main ◽  
Günter Wunner ◽  
Walter Dieter Heiss
Keyword(s):  
Exceptional Point ◽  
Third Order ◽  
Waveguide System

scholarly journals High-order exceptional point based optical sensor

2021 ◽  
Vol 29 (4) ◽  
pp. 6080
Author(s):  
Yulin Wu ◽  
Peiji Zhou ◽  
Ting Li ◽  
Weishi Wan ◽  
Yi Zou
Keyword(s):  
Optical Sensor ◽  
High Order ◽  
Exceptional Point

scholarly journals Paths of unitary access to exceptional points

2021 ◽  
Vol 2038 (1) ◽  
pp. 012026
Author(s):  
Miloslav Znojil
Keyword(s):  
Hilbert Space ◽  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Quantum Systems ◽  
Point Of View ◽  
Explicit Description ◽  
Direct Access ◽  
Exceptional Point ◽  
Exceptional Points ◽  
Innovative Idea

Abstract With an innovative idea of acceptability and usefulness of the non-Hermitian representations of Hamiltonians for the description of unitary quantum systems (dating back to the Dyson’s papers), the community of quantum physicists was offered a new and powerful tool for the building of models of quantum phase transitions. In this paper the mechanism of such transitions is discussed from the point of view of mathematics. The emergence of the direct access to the instant of transition (i.e., to the Kato’s exceptional point) is attributed to the underlying split of several roles played by the traditional single Hilbert space of states ℒ into a triplet (viz., in our notation, spaces K and ℋ besides the conventional ℒ ). Although this explains the abrupt, quantum-catastrophic nature of the change of phase (i.e., the loss of observability) caused by an infinitesimal change of parameters, the explicit description of the unitarity-preserving corridors of access to the phenomenologically relevant exceptional points remained unclear. In the paper some of the recent results in this direction are summarized and critically reviewed.

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