scholarly journals Simulation Research on Blood Detection Sensing with Parity-Time Symmetry Structure

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1030
Author(s):  
Lingjun Yi ◽  
Changhong Li
Keyword(s):  
Defect Mode ◽  
Detection Performance ◽  
Unit Cell ◽  
Pt Symmetry ◽  
Simulation Research ◽  
Time Symmetry ◽  
Performance Indexes ◽  
Sensing Model ◽  
Concentration Changes ◽  
Symmetry Structure

To realize the design of a medical sensor with excellent comprehensive performance indexes, herein, a plasma concentration sensing model satisfying the Parity-Time (PT) symmetric condition is proposed. In this paper, the transfer matrix method was used to simulate the transmittance spectrum of the structure, according to the amplification effect on defect mode transmission and various detection performance indexes of the structure. We numerically optimized the parameters of the structure, such as the number of PT-symmetry unit cell N, the sample layer thickness dD as well as the macroscopic Lorentz oscillation intensity α in the PT-symmetry unit cell. The calculation results demonstrate that when the sample concentration changes from 0 g/L to 50 g/L, the wavelength of defect peak shifts from 1538 nm to 1561 nm, and the average quality factor, sensitivity, average figure of merit, average detection limit and average resolution of the structure can reach 78,564, 0.4409 nm/(g/L) (or 227.05 nm/RIU), 11,515 RIU−1, 5.1 × 10−6 RIU and 0.038 g/L, respectively. Not only the sensitivity and resolution of the PT-symmetry structure are better than that of the similar sensors, but it also has excellent comprehensive detection performance, which indicates that the developed sensor can be used in high-precision biomedical detection devices.

scholarly journals Simulation Study of In-Phase and Out-Phase Enhanced Absorption of Graphene Based on Parity–Time Symmetry One-Dimensional Photonic Crystal Structure

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1513
Author(s):  
Lingjun Yi ◽  
Changhong Li
Keyword(s):  
Photonic Crystal ◽  
Electric Field ◽  
Optical Communication ◽  
Communication Systems ◽  
Pt Symmetry ◽  
Square Wave ◽  
Enhanced Absorption ◽  
Time Symmetry ◽  
Optical Communication Systems ◽  
Symmetry Structure

In the field of modern optical communication systems and photoelectric detection, new components with complex functions and excellent performance are urgently needed. In this paper, a graphene-based parity–time (PT) symmetry structure is proposed, which is achieved by preparing the graphene layer on the top of a PT-symmetry photonic crystal. The transfer matrix method was used to calculate the absorptance of graphene, and a unique amplified absorption effect was found. Meanwhile, the peak value and wavelength position of the absorption can be modulated via the applied electric field. The results show that by adjusting the negative square-wave electric field from −3.5 × 10−5 to −13.5 × 10−5 V/nm (or the positive square-wave electric field from 2 × 10−5 to 11 × 10−5 V/nm), the proposed structure can achieve in-phase (or out-phase) enhanced absorption for the communication wavelength 1550 nm, with the absorption of graphene from 17 to 28 dB (or 30 to 15 dB) corresponding to the square-wave modulation electric field change. The modulable absorption properties of graphene in the structure have potential in optoelectronic devices and optical communication systems.

scholarly journals Quantum Zeno effects across a parity-time symmetry breaking transition in atomic momentum space

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Tao Chen ◽  
Wei Gou ◽  
Dizhou Xie ◽  
Teng Xiao ◽  
Wei Yi ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
State Of The Art ◽  
Cold Atom ◽  
Pt Symmetry ◽  
Level System ◽  
Flexible Control ◽  
Time Symmetry ◽  
Symmetry Phase ◽  
Lattice Quantum ◽  
Atomic Momentum

AbstractWe experimentally study quantum Zeno effects in a parity-time (PT) symmetric cold atom gas periodically coupled to a reservoir. Based on the state-of-the-art control of inter-site couplings of atoms in a momentum lattice, we implement a synthetic two-level system with passive PT symmetry over two lattice sites, where an effective dissipation is introduced through repeated couplings to the rest of the lattice. Quantum Zeno (anti-Zeno) effects manifest in our experiment as the overall dissipation of the two-level system becoming suppressed (enhanced) with increasing coupling intensity or frequency. We demonstrate that quantum Zeno regimes exist in the broken PT symmetry phase, and are bounded by exceptional points separating the PT symmetric and PT broken phases, as well as by a discrete set of critical coupling frequencies. Our experiment establishes the connection between PT-symmetry-breaking transitions and quantum Zeno effects, and is extendable to higher dimensions or to interacting regimes, thanks to the flexible control with atoms in a momentum lattice.

scholarly journals Manifestation of the spontaneous parity-time symmetry breaking phase transition in hot-electron photodetection based on a tri-layered metamaterial

Nanophotonics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 495-504 ◽  
Author(s):  
Qiang Bai
Keyword(s):  
Phase Transition ◽  
Theoretical Model ◽  
Symmetry Breaking ◽  
Pt Symmetry ◽  
Coupled Mode Theory ◽  
Hot Electron ◽  
Electron Device ◽  
Coupled Mode ◽  
Time Symmetry ◽  
Existence Conditions

AbstractWe theoretically and numerically demonstrate that the spontaneous parity-time (PT) symmetry breaking phase transition can be realized respectively by using two independent tuning ways in a tri-layered metamaterial that consists of periodic array of metal-semiconductor Schottky junctions. The existence conditions of PT symmetry and its phase transition are obtained by using a theoretical model based on the coupled mode theory. A hot-electron photodetection based on the same tri-layered metamaterial is proposed, which can directly show the spontaneous PT symmetry breaking phase transition in photocurrent and possesses dynamical tunability and switchability. This work extends the concept of PT symmetry into the hot-electron photodetection, enriches the functionality of the metamaterial and the hot-electron device, and has varieties of potential and important applications in optoelectronics, photodetection, photovoltaics, and photocatalytics.

scholarly journals Observation of non-Bloch parity-time symmetry and exceptional points

2020 ◽  
Author(s):  
Peng Xue ◽  
Lei Xiao ◽  
Tianshu Deng ◽  
Kunkun Wang ◽  
Zhong Wang ◽  
...  
Keyword(s):  
Brillouin Zone ◽  
Skin Effect ◽  
Quantum Walks ◽  
Pt Symmetry ◽  
Great Promise ◽  
Single Photons ◽  
Band Theory ◽  
Exceptional Points ◽  
Time Symmetry ◽  
Transition Points

Abstract Parity-time (PT)-symmetric Hamiltonians have widespread significance in non-Hermitian physics. A PT-symmetric Hamiltonian can exhibit distinct phases with either real or complex eigen spectrum, while the transition points in between, the so-called exceptional points, give rise to a host of critical behaviors that holds great promise for applications. For spatially periodic non-Hermitian systems, PT symmetries are commonly characterized and observed in line with the Bloch band theory, with exceptional points dwelling in the Brillouin zone. Here, in non-unitary quantum walks of single photons, we uncover a novel family of exceptional points beyond this common wisdom. These "non-Bloch exceptional points" originate from the accumulation of bulk eigenstates near boundaries, known as the non-Hermitian skin effect, and inhabit a generalized Brillouin zone. Our finding opens the avenue toward a generalized PT-symmetry framework, and reveals the intriguing interplay among PT symmetry, non-Hermitian skin effect, and non-Hermitian topology.

scholarly journals Highly Localized and Efficient Energy Harvesting in a Phononic Crystal Beam: Defect Placement and Experimental Validation

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 391 ◽  
Author(s):  
Xu-Feng Lv ◽  
Xiang Fang ◽  
Zhi-Qiang Zhang ◽  
Zhi-Long Huang ◽  
Kuo-Chih Chuang
Keyword(s):  
Energy Harvesting ◽  
Point Defect ◽  
Polyvinylidene Fluoride ◽  
Experimental Validation ◽  
Flexural Rigidity ◽  
Phononic Crystal ◽  
Defect Mode ◽  
Unit Cell ◽  
Pvdf Film ◽  
Efficient Energy

We study energy harvesting in a binary phononic crystal (PC) beam at the defect mode. Specifically, we consider the placement of a mismatched unit cell related to the excitation point. The mismatched unit cell contains a perfect segment and a geometrically mismatched one with a lower flexural rigidity which serves as a point defect. We show that the strain in the defect PC beam is much larger than those in homogeneous beams with a defect segment. We suggest that the defect segment should be arranged in the first unit cell, but not directly connected to the excitation source, to achieve efficient less-attenuated localized energy harvesting. To harvest the energy, a polyvinylidene fluoride (PVDF) film is attached on top of the mismatched segment. Our numerical and experimental results indicate that the placement of the mismatched segment, which has not been addressed for PC beams under mechanical excitation, plays an important role in efficient energy harvesting based on the defect mode.

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