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Higher-order exceptional points in waveguidecoupled microcavities:perturbation induced frequency splitting and mode patterns

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Photonics Research 2023年第10期11卷 I0011-I0021页

作者： JULIUS KULLIG DANIEL GROM SEBASTIAN KLEMBT JAN WIERSIG institut für physik Otto-von-Guericke-Universität Magdeburg39106 MagdeburgGermany Technische physik and Würzburg-dresden cluster of excellence ct.qmat Physikalisches Institut and Wilhelm-Conrad-Röntgen-Research Center for Complex Material SystemsAm HublandUniversity of Würzburg97070 WürzburgGermany

Exceptional points are degeneracies in the spectrum of non-Hermitian open systems where at least two eigenfrequencies and simultaneously the corresponding eigenstates of the Hamiltonian ***,the robust construction of higher-order exceptional points with more than two degenerate eigenfrequencies and eigenstates is challenging but yet worthwhile for *** this paper,we reconsider the formation of higher-order exceptional points through waveguide-coupled microring cavities and asymmetric *** this context,we demonstrate the influence of perturbations on the frequency splitting of the *** generate higher-order exceptional points in a simple and robust way,a mirror-induced asymmetric backscattering approach is *** addition to the exceptional-point enhanced sensing capabilities of such systems,also a cavity-selective sensitivity is achieved for particle *** results are motivated by an effective Hamiltonian description and verified by full numerical simulations of the dielectric structure.

关键词： structure exceptional splitting

Direct nanoscopic observation of plasma waves in the channel of a graphene field-effect transistor

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Light(Science & Applications) 2020年第1期9卷 1079-1085页

作者： Amin Soltani Frederik Kuschewski Marlene Bonmann Andrey Generalov Andrei Vorobiev Florian Ludwig Matthias M.Wiecha Dovile Cibiraite Frederik Walla Stephan Winnerl Susanne C.Kehr Lukas M.Eng Jan Stake Hartmut G.Roskos physikalisches institut Johann Wolfgang Goethe-UniversitatMax-von-Laue-Str.1D-60438 Frankfurt am MainGermany institut für Angewandte physik Technische Universitat DresdenNöthnitzer Str.61D-01187 DresdenGermany Department of Microtechnology and Nanoscience Chalmers University of TechnologySE-41296 GothenburgSweden institute of Ion Beam Physics and Materials Research Helmholtz-Zentrum Dresden-RossendorfBautzner Landstraße 400D-01328 DresdenGermany Complexity and Topology in Quantum Matter(ct.qmat) Cluster of Excellence EXC 2147Dresden/WurzburgGermany Department of Electronics and Nanoengineering Aalto UniversityTietotie 302150EspooFinland

Plasma waves play an important role in many solid-state phenomena and *** also become significant in electronic device structures as the operation frequencies of these devices increase.A prominent example is field-effect transistors(FETs),that witness increased attention for application as rectifying detectors and mixers of electromagnetic waves at gigahertz and terahertz frequencies,where they exhibit very good sensitivity even high above the cut-off frequency defined by the carrier transit *** theory predicts that the coupling of radiation at THz frequencies into the channel of an antenna-coupled FET leads to the development of a gated plasma wave,collectively involving the charge carriers of both the two-dimensional electron gas and the gate *** this paper,we present the first direct visualization of these *** graphene FETs containing a buried gate electrode,we utilize near-field THz nanoscopy at room temperature to directly probe the envelope function of the electric field amplitude on the exposed graphene sheet and the neighboring antenna *** of the field distribution documents that wave injection is unidirectional from the source side since the oscillating electrical potentials on the gate and drain are equalized by capacitive *** plasma waves,excited at 2 THz,are overdamped,and their decay time lies in the range of 25-70 *** this short decay time,the decay length is rather long,i.e.,0.3-0.5μm,because of the rather large propagation speed of the plasma waves,which is found to lie in the range of 3.5-7×10^(6)m/s,in good agreement with *** propagation speed depends only weakly on the gate voltage swing and is consistent with the theoretically predicted 1/4 power law.

关键词： antenna channel transistor

Author Correction:Different types of spin currents in the comprehensive materials database of nonmagnetic spin Hall effect

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npj Computational Materials 2021年第1期7卷 1762-1763页

作者： Yang Zhang Qiunan Xu Klaus Koepernik Roman Rezaev Oleg Janson Jakub Železný Tomáš Jungwirth Claudia Felser Jeroen van den Brink Yan Sun Max Planck institute for Chemical Physics of Solids 01187 Dresden Germany Leibniz institute for Solid State and Materials Research 01069 Dresden Germany Department of Physics Massachusetts Institute of Technology Cambridge MA 02139 USA Center for Nanoscale Systems Faculty of Arts and Sciences Harvard University 11 Oxford Street LISE 308 Cambridge MA 02138 USA institut fur theoretische physik and wurzburg-dresden cluster of excellence ct.qmat Dresden University of Technology 01062 Dresden Germany institute of Physics Czech Academy of Sciences Cukrovarnicka 10 162 00 Praha 6 Czech Republic School of Physics and Astronomy University of Nottingham NG7 2RD Nottingham United Kingdom

The original version of this Article contained errors in Fig.3b,d,in which a factor of“100”should be included in the unit for both y-axis labels“SHC[100(ħ/e)(S/cm)]”.This has been corrected in both the PDF and HTM... 详细信息

关键词： database HTML include

Invariant-mass distribution of top-quark pairs and top-quark mass determination

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Chinese Physics C 2020年第9期44卷 1-6页

作者： Wan-Li Ju Guoxing Wang Xing Wang Xiaofeng Xu Yongqi Xu Li Lin Yang School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China institute for Particle Physics Phenomenology Durham UniversityDurham DH13LEUK PRISMA+cluster of excellence&Mainz institute for Theoretical Physics Johannes Gutenberg University55099 MainzGermany institut für theoretische physik Universität BernSidlerstrasse 5CH-3012 BernSwitzerland Zhejiang institute of Modern Physics Department of PhysicsZhejiang UniversityHangzhou 310027China

In this study,we investigate the invariant-mass distribution of top-quark pairs near the 2mt threshold,which strongly influences the determination of the top-quark mass ***-order non-relativistic corrections lead to large contributions,which are not included in the state-of-the-art theoretical predictions.A factorization formula is derived to resum such corrections to all orders in the strong-coupling,and necessary ingredients are calculated to perform the resummation at next-to-leading *** combine the resummation with fixed-order results and present phenomenologically relevant numerical *** resummation effect significantly increases the differential cross-section in the threshold region and makes the theoretical prediction more compatible with experimental *** estimate that using our prediction in the determination of mt will lead to a value closer to the direct measurement result.

关键词： top quark QCD resummation

High-Tc superconductor Fe（Se,Te） monolayer:an intrinsic,scalable and electrically tunable Majorana platform

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National Science Review 2022年第3期9卷 11-18页

作者： Xianxin Wu Xin Liu Ronny Thomale Chao-Xing Liu institut für theoretische physik und Astrophysik Julius-Maximilians-Universit?t Würzburg School of Physics Huazhong University of Science and Technology Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Department of Physics the Pennsylvania State University

Iron-based superconductors have been identified as a novel platform for realizing Majorana zero modes（MZMs） without heterostructures, due to their intrinsic topological properties and high-Tc superconductivity. In the two-dimensional limit, the FeTe;1-x;Se;x;monolayer, a topological band inversion has recently been experimentally observed. Here, we propose to create MZMs by applying an in-plane magnetic field to the FeTe;1-x;Se;x;monolayer and tuning the local chemical potential via electric *** to the anisotropic magnetic couplings on edges, an in-plane magnetic field drives the system into an intrinsic high-order topological superconductor phase with Majorana corner modes. furthermore, MZMs can occur at the domain wall of chemical potentials at either one edge or certain type of tri-junction in the two-dimensional bulk. Our study not only reveals the FeTe;1-x;Se;x;monolayer as a promising Majorana platform with scalability and electrical tunability and within reach of contemporary experimental capability,but also provides a general principle to search for realistic realization of high-order topological superconductivity.

关键词： high-order topological superconductivity Majorana zero modes iron-based superconductors

Effects of a phase transition on two-pion interferometry in heavy ion collisions at √SNN=2.4-7.7 GeV

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Science China(Physics,Mechanics & Astronomy) 2023年第3期66卷 88-97页

作者： Pengcheng Li Jan Steinheimer Tom Reichert Apiwit Kittiratpattana Marcus Bleicher Qingfeng Li institut fur theoretische physik Johann Wolfgang Goethe Universitat FrankfurtFrankfurt am Main 60438Germany School of Science Huzhou UniversityHuzhou 313000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Frankfurt institute for Advanced Studies Frankfurt am Main 60438Germany GSI Helmholtzzentrum f¨urSchwerionenforschung GmbH Darmstadt 64291Germany Helmholtz Research Academy Hesse for FAIR(HFHF) GSI Helmholtz Center for Heavy Ion PhysicsCampus FrankfurtFrankfurt am Main 60438Germany Center of excellence in High Energy Physics&Astrophysics School of PhysicsSuranaree University of TechnologyNakhon Ratchasima 30000Thailand

Hanbury-Brown-Twiss(HBT) correlations for charged pions in central Au+Au collisions at √SNN=2.4-7.7 GeV(corresponding to beam kinetic energies in the fixed target frame from Elab=1.23 to 30 GeV/nucleon) are calculated using the ultra-relativistic quantum molecular dynamics model with different equations of state(EoSs).The effects of a phase transition at high baryon densities are clearly observed in the explored HBT *** results show that the available data on the HBT radii,RO/RSand R^(2)_(O)-R^(2)_(S),in the investigated energy region favor a relatively stiff EoS at low beam energies,which then turns into a soft EoS at high collision energies consistent with astrophysical constraints on the high-density EoS of quantum chromodynamics(QCD).The specific effects of two different phase transition scenarios on RO/RSand R^(2)_(O)-R^(2)_(S)are investigated.A phase transition with a significant softening of the EoS below four times the nuclear saturation density can be excluded using HBT *** results highlight that the pion’s RO/RSand R^(2)_(O)-R^(2)_(S)are sensitive to the stiffness of the EoS and can be used to constrain and understand the QCD EoS in a high baryon density region.

关键词： heavy ion collisions HBT correlation equation of state

Precision Tests of the Nonlinear Mode Coupling of Anisotropic Flow via High-Energy Collisions of Isobars

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Chinese Physics Letters 2023年第4期40卷 18-22页

作者：贾江涌 Giuliano Giacalone 张春健 Department of Chemistry Stony Brook UniversityStony BrookNY 11794USA Physics Department Brookhaven National LaboratoryUptonNY 11976USA institut fur theoretische physik Universitat HeidelbergPhilosophenweg 1669120 HeidelbergGermany

Valuable information on dynamics of expanding fluids can be inferred from the response of such systems to perturbations in their initial *** apply this technique in high-energy^(96)Ru+^(96)Ru and^(96)Zr+^(96)Zr collisions to scrutinize the expansion dynamics of the quark-gluon plasma,where the initial geometry perturbations are sourced by the differences in deformations and radial profiles between^(96)Ru and^(96)Zr,and the collective response is captured by the change in anisotropic flow Vn between the two collision *** a transport model,we analyze how the nonlinear coupling between lower-order flow harmonics V_(2)and V_(3)to the higher-order flow harmonics V_(4)and V_(5),expected to scale as V_(4)NL= χ_(4)V_(2)2and V_(5)NL= χ_(5)V_(2)V_(3),gets modified as one moves from^(96)Ru+^(96)Ru to^(96)Zr+^(96)Zr *** find that these scaling relations are valid to high precision:variations of order 20% in V_(4)NLand V_(5)NLdue to differences in quadrupole deformation,octupole deformation,and nuclear skin modify χ_(4)and χ_(5)by about 1–2%.Percent-level deviations are however larger than the expected experimental uncertainties and could be ***,collisions of isobars with different nuclear structures are a unique tool to isolate subtle nonlinear effects in the expansion of the quark-gluon plasma that would be otherwise impossible to access in a single collision system.

关键词： collision harmonics perturbations

Leading order relativistic chiral nucleon-nucleon interaction

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Chinese Physics C 2018年第1期42卷 97-106页

作者：任修磊李凯文耿立升龙炳蔚 Peter Ring 孟杰 State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing 100871 China institut for theoretische physik II Ruhr-Universitat Bochum D-44780 Bochum Germany School of Physics and Nuclear Energy Engineering & International Research Center for Nuclei and Particles in the Cosmos Beihang University Beijing 100191 China Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang University Beijing 100191 China Center for Theoretical Physics Department of Physics Sichuan University Chengdu Sichuan 610064 China physik Department Technische Universitat Miinchen D-85748 Garching Germany

Motivated by the successes of relativistic theories in studies of atomic/molecular and nuclear systems and the need for a relativistic chiral force in relativistic nuclear structure studies, we explore a new relativistic scheme to construct the nucleon-nucleon interaction in the framework of covariant chiral effective field theory. The chiral interaction is formulated up to leading order with covariant power counting and a Lorentz invariant chiral *** find that the relativistic scheme induces all six spin operators needed to describe the nuclear force. A detailed investigation of the partial wave potentials shows a better description of the;S——0 and;P;phase shifts than the leading order Weinberg approach, and similar to that of the next-to-leading order Weinberg approach. For the other partial waves with angular momenta J≥1, the relativistic results are almost the same as their leading order non-relativistic counterparts.

关键词： covariant chiral perturbation theory nucleon-nucleon interaction relativistic scattering equation

Unveiling a critical stripy state in the triangular-lattice SU(4)spin-orbital model

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Science Bulletin 2022年第9期67卷 918-923,M0003页

作者： Hui-Ke Jin Rong-Yang Sun Hong-Hao Tu Yi Zhou Department of Physics TQM Technische Universität MünchenJames-Franck-Straûe 1D-85748 GarchingGermany Kavli institute for Theoretical Sciences University of Chinese Academy of SciencesBeijing 100190China Computational Materials Science Research Team RIKEN Center for Computational Science(R-CCS)KobeHyogo 650-0047Japan Quantum Computational Science Research Team RIKEN Center for Quantum Computing(RQC)WakoSaitama 351-0198Japan institut für theoretische physik Technische Universität Dresden01062 DresdenGermany institute of Physics Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory DongguanDongguan 523808China CAS Center for excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

The simplest spin-orbital model can host a nematic spin-orbital liquid state on the triangular *** provide clear evidence that the ground state of the SU(4)Kugel-Khomskii model on the triangular lattice can be well described by a‘‘single”Gutzwiller projected wave function with an emergent parton Fermi surface,despite it exhibits strong finite-size effect in quasi-one-dimensional *** finite-size effect can be resolved by the fact that the parton Fermi surface consists of open orbits in the reciprocal ***,a stripy liquid state is expected in the two-dimensional limit,which preserves the SU(4)symmetry while breaks the translational symmetry by doubling the unit cell along one of the lattice vector *** is indicative that these stripes are critical and the central charge is c=3,in agreement with the SU(4)1Wess-Zumino-Witten conformal field *** these results are consistent with the Lieb-Schultz-Mattis-Oshikawa-Hastings theorem.

关键词： Quantum spin liquid Spin-orbital liquid Stripes SU(4)symmetry Fractionalization