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Abstract We propose a computational methodology to perform inverse design of quantum spin hall effect (QSHE)-based phononic topological insulators. We first obtain two-fold degeneracy, or a Dirac cone, in the band structure using a level set-based topology optimization approach. Subsequently, four-fold degeneracy, or a double Dirac cone, is obtained by using zone folding, after which breaking of translational symmetry, which mimics the effect of strong spin-orbit coupling and which breaks the four-fold degeneracy resulting in a bandgap, is applied. We use the approach to perform inverse design of hexagonal unit cells of C 6 and C 3 symmetry. The numerical examples show that a topological domain wall with two variations of the designed metamaterials exhibit topologically protected interfacial wave propagation, and also demonstrate that larger topologically-protected bandgaps may be obtained with unit cells based on C 3 symmetry. [ABSTRACT FROM AUTHOR]

Due to the bending resistance and defect immunity of the topological optical structure, topological photonics is extended to researching Fano line shapes or electromagnetically induced transparency-like (EIT-like) line shapes. In this paper, two-dimensional photonic crystal with Kekul e ´ distortion is designed to realize quantum spin Hall effect and quantum valley Hall effect simultaneously. The stable topological corner states and edge states are obtained. Corner states as dark modes interfere with edge states as bright mode to induce Fano or EIT-like line shapes. As far as we know, we first realize the coexistence of Fano and EIT-like line shapes based on the coexistence of quantum spin Hall effect and quantum valley Hall effect. Our results provide a new way to realize multi-channel sensing technology. • We design a photonic crystal with generalized Kekul e ´ modulation based on dielectric materials. • The 2D photonic crystals can realize the coexistence of quantum spin Hall effect and quantum valley Hall effect. • Corner states as dark modes interfere with edge states as bright modes to induce Fano or EIT-like line shapes. • We realize the coexistence of Fano and EIT line shapes based on the quantum spin Hall effect and quantum valley Hall effect. • The larger peak value of Fano and EIT resonances can enhance the nonlinearity of materials. [ABSTRACT FROM AUTHOR]

The article discusses the debate over the measurement of a proton by physicist Randolf Pohl and colleagues. An overview is presented of the quantum electrodynamics (QED) theory of the orbital energy of electron emissions of photons, which was applied to the measurement of protons by Pohl and team. The researchers used muon hydrogen atoms in a hydrogen gas to determine the Lamb shift of electron energy with a low-energy particle accelerator, finding that the radius of the muon proton was 4 percent less than other measurements of hydrogen atoms. Other topics include validation of the results with electron scattering measurements, the quantum spin of muons, and the concept of dark photons.

Keywords: Chemical Physics; Chemistry; Condensed Matter Physics; Health and Medicine; Mathematics; Max Planck Institute for Chemical Physics of Solids; Physics; Technology EN Chemical Physics Chemistry Condensed Matter Physics Health and Medicine Mathematics Max Planck Institute for Chemical Physics of Solids Physics Technology 910 910 1 07/17/23 20230721 NES 230721 2023 JUL 21 (NewsRx) -- By a News Reporter-Staff News Editor at Health & Medicine Week -- Prof. Claudia Felser is a director at the Max Planck Institute for Chemical Physics of Solids in Germany, Prof. B. Andrei Bernevig is a Professor of Physics at Princeton University in the United States and Visiting Ikerbasque Professor at Donostia International Physics Center in Spain. Chemical Physics, Chemistry, Condensed Matter Physics, Health and Medicine, Mathematics, Max Planck Institute for Chemical Physics of Solids, Physics, Technology Professor Claudia Felser Claudia Felser studied chemistry and physics at the University of Cologne, completing her diploma in solid state chemistry (1989) and her doctorate in physical chemistry (1994). [Extracted from the article]

We study the tunable quantum Hall effects in a non-Abelian honeycomb optical lattice which is a multi-Dirac-point system. We find that the quantum Hall effects present different features with the change in relative strengths of several perturbations. Namely, the quantum spin Hall effect can be induced by gauge-field-dressed next-nearest-neighbor hopping, which, together with a Zeeman field, can induce the quantum anomalous Hall effect characterized by different Chern numbers. Furthermore, we find that the edge states of the multi-Dirac-point system represent very different features for different boundary geometries, in contrast with the generic two-Dirac-point system. Our study extends the borders of the field of quantum Hall effects in a honeycomb optical lattice with multivalley degrees of freedom. [ABSTRACT FROM AUTHOR]

Driven optical lattices permit the engineering of effective dynamics with well-controllable tunneling properties. By specifically designing polychromatic driving forces, we describe how an optimal realization of a tunable Chern insulator can be achieved with a system of interacting particles on a shaken hexagonal lattice. Its implementation does not require shallow lattices and favors the study of strongly correlated phases with nontrivial topology. [ABSTRACT FROM AUTHOR]

Chaotic dynamics in microcavity have promoted massive discoveries and applications ranging from decoherence suppression to broadband optical devices. However, a chaotic light source on the chip is more likely to suffer from the ambient randomness and perturbations than its bulk counterparts, vanishing chaotic dynamics. Topological protection provides a robust framework for manipulating the periodic wave dynamics, whereas the symmetric layout in topological protection poses a direct challenge to leveraging this notion in chaotic dynamics. Here, we discover that benefiting from an engineered exceptional point, the non-Hermitian-enhanced topological protection yields zero modes and switches the chaotic dynamics. As a result, this new effect significantly extends the topologically protected chaotic dynamics to a more general trivial phase beyond the constraint of the topological invariant. More importantly, the zero modes merit robust chaotic dynamics prevail with intentionally introduced perturbations. Moreover, we find that an extended photonics lattice composed of an increased number of microcavities not only offers a more robust topological protection but also can delay the chaos generation, providing a new degree of freedom to harness the chaos generation. This study presents a promising approach for robust on-chip chaotic light sources and advances various explorations on multibody non-Hermitian physics. [ABSTRACT FROM AUTHOR]

We propose a scheme to investigate the interplay between the Kondo-exchange interaction and the quantum spin Hall effect with ultracold fermionic alkaline-earth-metal atoms trapped in two-dimensional optical lattices using ultracold collision and laser-assisted tunneling. In the strong Kondo-coupling regime, although the loop trajectory of the mobile atom disappears, collective dynamics of an atom pair in two clock states can exhibit an unexpected spin-dependent cyclotron orbit in a plaquette, realizing the quantum spin Hall effect of the Kondo singlet. We demonstrate that the collective cyclotron dynamics of the spin-zero Kondo singlet is governed by an effective Harper-Hofstadter model in addition to second-order diagonal tunneling. [ABSTRACT FROM AUTHOR]

We study the θ dependence of the continuum limit of 2D U(N) gauge theories defined on compact manifolds, with special emphasis on spherical (g=0) and toroidal (g=1) topologies. We find that the coupling between U(1) and SU(N) degrees of freedom survives the continuum limit, leading to observable deviations of the continuum topological susceptibility from the U(1) behavior, especially for g=0, in which case deviations remain even in the large N limit. [ABSTRACT FROM AUTHOR]

We consider two semi-infinite magnetoelectric media separated by a planar interface whose electromagnetic response is described by axion electrodynamics. The time-dependent Green's function characterizing this geometry is obtained by a method that can be directly generalized to cylindrical and spherical configurations of two magnetoelectrics separated by an interface. We establish the far-field approximation of Green's function and apply these results to the case of a charged particle moving from one medium to the other at a high constant velocity perpendicular to the interface. From the resulting angular distribution of the radiated energy per unit frequency, we provide theoretical evidence for the emergence of reversed Vavilov-Čerenkov radiation in naturally existing magnetoelectric media. In the case where one of the magnetoelectrics is a 3D topological insulator, TlBiSe2, for example, located in front of a regular insulator, we estimate that an average forward Vavilov-Čerenkov radiation with frequency 2.5 eV (500 nm) will produce a highly suppressed reversed Vavilov-Čerenkov radiation, which can be characterized by an effective frequency in the range of ~ (4×10-3-0.5) meV. However, this value compares favorably with recent measurements in left-handed metamaterials yielding reversed Vavilov-Čerenkov radiation with frequencies of the order of (1.2-3.9) × 10-2 meV. [ABSTRACT FROM AUTHOR]

In this paper, we study the topological susceptibility of two-dimensional U(N) gauge theories. We provide explicit expressions for the partition function and the topological susceptibility at finite lattice spacing and finite volume. We then examine the particularly simple case of the Abelian U(1) theory, the continuum limit, and the infinite volume limit, and we finally discuss the large N limit of our results. [ABSTRACT FROM AUTHOR]

The realization of the spin-Hall effect in quantum wells has led to a plethora of studies regarding the properties of the edge states of a two-dimensional topological insulator. These edge states constitute a class of one-dimensional liquids, called the helical liquid, where an electron's spin quantization axis is tied to its momentum. In contrast to one-dimensional conductors, magnetic impurities--below the Kondo temperature--cannot block transport and one expects the current to circumvent the impurity. To study this phenomenon, we consider the single-impurity Anderson model embedded into an edge of a Kane-Mele ribbon with up to 512×80 sites and use the numerically exact continuous time quantum Monte Carlo method to study the Kondo effect. We present results on the temperature dependence of the spectral properties of the impurity and the bulk system that show the behavior of the system in the various regimes of the Anderson model. A view complementary to the single-particle spectral functions can be obtained using the spatial behavior of the spin-spin correlation functions. Here we show the characteristic, algebraic decay in the edge channel near the impurity. [ABSTRACT FROM AUTHOR]