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Dynamical encirclement of an Exceptional Point (EP) and corresponding time-asymmetric mode evolution properties due to breakdown in adiabatic theorem have been a key to range of exotic physical effects in various open atomic, molecular and…

Optics · Physics 2019-04-17 Arnab Laha , Sibnath Dey , Harsh K. Gandhi , Abhijit Biswas , Somnath Ghosh

We demonstrate that a circuit comprising two unstable LC resonators coupled via a gyrator supports an exceptional point of degeneracy (EPD) with purely real eigenfrequency. Each of the two resonators includes either a capacitor or an…

Applied Physics · Physics 2021-10-06 Kasra Rouhi , Alireza Nikzamir , Alexander Figotin , Filippo Capolino

Exceptional points (EPs), i.e., non-Hermitian degeneracies at which eigenvalues and eigenvectors coalesce, can be realized by tuning the gain/loss contrast of different modes in non-Hermitian systems or by engineering the asymmetric…

We investigate how a single resonator with a time-modulated component extracts power from an external ambient source. However, the collected power is largely dependent on the precise choice of the modulation signal frequency. We focus on…

Applied Physics · Physics 2023-03-21 Alireza Nikzamir , Kasra Rouhi , Alexander Figotin , Filippo Capolino

A backward wave optical parametric oscillator (BWOPO) waveguide in periodically poled Rb-doped KTP is presented. The waveguide exhibits low loss (0.16 dB/cm) and has an oscillation threshold, almost 20 times lower than the corresponding…

We propose a new amplification regime based on synchronous operation of four degenerate electromagnetic (EM) modes in a slow-wave structure and the electron beam, referred to as super synchronization. These four EM modes arise in a…

Plasma Physics · Physics 2016-04-19 Mohamed A. K. Othman , Mehdi Veysi , Alexander Figotin , Filippo Capolino

The dispersion of a three-way waveguide is engineered to exhibit exceptional modal characteristics. Two coupled waveguides with Parity-Time (PT) symmetry have been previously demonstrated to exhibit second order exceptional points of…

Applied Physics · Physics 2022-06-08 Farshad Yazdi , Tarek Mealy , Alireza Nikzamir , Robert Marosi , Filippo Capolino

A periodically loaded waveguide composed of periodic discrete nonlinear gain and radiating elements supports a stable oscillation regime related to the presence of an exceptional point of degeneracy (EPD). After reaching saturation, the EPD…

We demonstrate the existence of exceptional points of degeneracy (EPD) of periodic eigenstates in non-Hermitian coupled chains of dipolar scatterers. Guided modes supported by these structures can exhibit an EPD in their dispersion diagram…

Optics · Physics 2017-03-22 Mohamed A. K. Othman , Vincenzo Galdi , Filippo Capolino

We demonstrate several new aspects of exceptional points of degeneracy (EPD) pertaining to propagation in two uniform coupled transmission-line structures. We describe an EPD using two different approaches - by solving an eigenvalue problem…

Applied Physics · Physics 2018-04-11 George W. Hanson , Alexander B. Yakovlev , Mohamed Othman , Filippo Capolino

Quarter-wave OLEDS are microcavity devices that can operate in the low finesse limit and achieve high efficiency (> 300 lm/W) by using interference to reduce the onset current for the transition to stimulated emission. In this work we study…

Optics · Physics 2016-04-14 Mitchell C. Nelson

We propose an optomechanical design, consisting of a parity-time symmetric multilayer structure tuned at exceptional-point degeneracy (EPD), with an adjustable layer that is coupled to micromechanical springs. The deflections of this layer…

Applied Physics · Physics 2020-07-01 Rodion Kononchuk , Tsampikos Kottos

We propose a new principle of operation in vacuum electron-beam-based oscillators that leads to a low beam current for starting oscillations. The principle is based on super synchronous operation of an electron beam interacting with four…

Plasma Physics · Physics 2016-10-03 Mohamed A. K Othman , Mehdi Veysi , Alexander Figotin , Filippo Capolino

We demonstrate the existence of a special degeneracy condition, called degenerate band edge (DBE), between two Bloch modes in periodically loaded circular all-metallic waveguides at microwave frequencies. The DBE condition has been…

Optics · Physics 2016-04-19 Mohamed Othman , Filippo Capolino

Topological operations have the merit of achieving certain goals without requiring accurate control over local operational details. To date, topological operations have been used to control geometric phases, and have been proposed as a…

Optics · Physics 2016-09-13 H. Xu , D. Mason , L. Jiang , J. G. E. Harris

Exceptional points (EPs) are degeneracies of non-Hermitian operators where, in addition to the eigenvalues, corresponding eigenmodes become degenerate. Classical and quantum photonic systems with EPs have attracted tremendous attention due…

The properties of a degenerate band-edge (DBE) oscillator based on the synchronous interaction between a linear electron beam synchronized with four degenerate electromagnetic modes are presented. The DBE in the cold slow-wave structure is…

We demonstrate how exceptional points of degeneracy (EPDs) are induced in a single transmission line (TL) directly by applying periodic space-time modulation to the per-unit-length distributed capacitance. In such space-time modulated…

Applied Physics · Physics 2020-12-30 Kasra Rouhi , Hamidreza Kazemi , Alexander Figotin , Filippo Capolino

The bond order wave (BOW) phase of the extended Hubbard model (EHM) in one dimension (1D) is characterized at intermediate correlation $U = 4t$ by exact treatment of $N$-site systems. Linear coupling to lattice (Peierls) phonons and…

Strongly Correlated Electrons · Physics 2011-06-28 Manoranjan Kumar , Zolt'an G. Soos

We propose an efficient optomechanical mass sensor operating at exceptional points (EPs), non-hermitian degeneracies where eigenvalues of a system and their corresponding eigenvectors simultaneously coalesce. The benchmark system consists…

Mesoscale and Nanoscale Physics · Physics 2019-08-07 P. Djorwé , Y. Pennec , B. Djafari-Rouhani