Article
Multidisciplinary Sciences
Minkyung Kim, Zihao Wang, Yihao Yang, Hau Tian Teo, Junsuk Rho, Baile Zhang
Summary: Researchers have designed and demonstrated a 3D photonic topological insulator (PTI) that exhibits self-guided topological surface states without the need for additional confinement. By removing spin-orbit coupling, this PTI opens new possibilities for manipulating photons at the outer surface of photonic bandgap materials.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Julian Schulz, Jiho Noh, Wladimir A. Benalcazar, Gaurav Bahl, Georg von Freymann
Summary: In this study, the authors experimentally demonstrate a photonic quadrupole topological insulator by breaking the symmetries of a mixed-orbital lattice and generating synthetic magnetic flux. The existence of the quadrupole topology is confirmed by observing protected zero-dimensional states that sit at mid-gap.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Jiong-Hao Wang, Yan-Bin Yang, Ning Dai, Yong Xu
Summary: Researchers predict a second-order topological insulating phase in amorphous systems without any crystalline symmetry, and find that structural disorder can induce this higher-order topological phase.
PHYSICAL REVIEW LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Jiachen Luo, Zongliang Du, Yilin Guo, Chang Liu, Weisheng Zhang, Xu Guo
Summary: An explicit topology optimization-based design paradigm is proposed for the design of photonic topological crystalline insulators (TCIs), which is successfully applied to design photonic TCIs with time-reversal symmetry in two-dimensional point groups, higher-order magnetic TCIs, and higher-order photonic TCIs. This methodology paves the way for inverse design of optimized photonic/phononic, multiphysics, and multifunctional three-dimensional TCIs.
Article
Optics
Guochao Wei, Zhenzhen Liu, Huizhou Wu, Licheng Wang, Shengxiang Wang, Junjun Xiao
Summary: We demonstrate tunable chiral edge states (CESs) with flexible group velocity and frequency range at the boundary of a valley photonic crystal (VPC). Our design includes a meta-structure supporting CESs in different frequency ranges and parallel and antiparallel CESs located at two opposite boundaries. The meta-structure also features a valley edge state connecting the top and bottom boundaries.
Article
Optics
Wenchao Yan, Weizhao Cheng, Weijie Liu, Feng Chen
Summary: In recent years, extensive studies have been conducted on topological insulators in one-dimensional periodic systems, particularly Su-Schrieffer-Heeger and trimer lattices. These models support topological edge states protected by lattice symmetry. To further investigate lattice symmetry in one-dimensional topological insulators, a modified version of the conventional trimer lattices called decorated trimer lattices was designed. Experimental demonstrations were conducted using the femtosecond laser writing technique, resulting in the observation of different types of topological edge states. Interestingly, the addition of vertical intracell coupling strength in the model transformed the energy band spectrum and generated unconventional topological edge states with longer localization lengths at a different boundary. This work provides novel insights into one-dimensional topological insulators in photonic lattices.
Article
Optics
Hironobu Yoshimi, Takuto Yamaguchi, Ryota Katsumi, Yasutomo Ota, Yasuhiko Arakawa, Satoshi Iwamoto
Summary: Experimental demonstration of topological slow light waveguides in valley photonic crystals, showing more efficient waveguiding in the topological mode compared to the non-topological mode.
Article
Physics, Applied
Weipeng Hu, Chao Liu, Jun Guo, Xiaoyu Dai, Shuangchun Wen, Yuanjiang Xiang
Summary: This study proposes a high-efficiency second-harmonic generation (SHG) using dual-frequency topological edge states (TESs) in topological photonic crystals (TPCs) with slow-light conditions. The wave vector matching and energy conservation conditions are achieved by adjusting the structural parameters of TPCs. The double-resonant nonlinear interaction between two TESs is enabled using a square lattice TPC. The topological localization of TESs and the long interaction time of the slow-light effect significantly increase the energy densities of the fundamental wave and SHG.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Hao-Ke Xu, Mingqiang Gu, Fucong Fei, Yi-Sheng Gu, Dang Liu, Qiao-Yan Yu, Sha-Sha Xue, Xu-Hui Ning, Bo Chen, Hangkai Xie, Zhen Zhu, Dandan Guan, Shiyong Wang, Yaoyi Li, Canhua Liu, Qihang Liu, Fengqi Song, Hao Zheng, Jinfeng Jia
Summary: Research has discovered that MnBi4Te7 is a topological insulator with quantum anomalous Hall effect and axion insulator phase. Through scanning tunneling spectroscopy, it has been observed that there is an electronic state at the edge of the magnetic MnBi2Te4 layer at 4.5 K, but not in the nonmagnetic Bi2Te3 layer. As the temperature increases, the edge state disappears, while the state induced by point defects persists.
Article
Chemistry, Multidisciplinary
Petr N. N. Kim, Dmitry P. P. Fedchenko, Natalya V. V. Rudakova, Ivan V. V. Timofeev
Summary: This study proposes a tiling photonic topological insulator constructed from connected prism resonators, which has a topologically-protected propagating state due to the disconnected faces of the edge resonators. The structure exhibits robustness against structural defects and scalability in wavelength and resonator size. The tiling is suggested for active topological photonic devices and laser arrays.
APPLIED SCIENCES-BASEL
(2023)
Review
Optics
Eran Lustig, Mordechai Segev
Summary: Topological photonics is a rapidly growing field that has expanded its scope by incorporating non-spatial degrees of freedom. This offers the possibility to observe fundamental and exotic phenomena, with the next challenge being identified as enhancing the fundamental features of photonic topological systems.
ADVANCES IN OPTICS AND PHOTONICS
(2021)
Article
Optics
Jiale Yuan, Chenran Xu, Han Cai, Da-Wei Wang
Summary: The proposed scheme efficiently transfers photons in a scalable one-dimensional waveguide array by transporting the topological defect state of a Su-Schrieffer-Heeger model, using a constant energy gap for protected excitation transfer. Additionally, quasi-periodic oscillations induced by the non-adiabatic effect can further speed up the transport process.
Article
Optics
Yulin Zhao, Feng Liang, Jianfei Han, Xiangru Wang, Deshuang Zhao, Bing-Zhong Wang
Summary: This paper proposes a new all-dielectric photonic crystal structure with tunable topological edge and corner states through the use of liquid crystals. The structure demonstrates a wider energy gap and robust topological protection, making it suitable for tunable optical waveguides, reconfigurable topological microcavities, and other intelligent topological optical/terahertz devices.
Article
Multidisciplinary Sciences
Gui-Geng Liu, Zhen Gao, Qiang Wang, Xiang Xi, Yuan-Hang Hu, Maoren Wang, Chengqi Liu, Xiao Lin, Longjiang Deng, Shengyuan A. Yang, Peiheng Zhou, Yihao Yang, Yidong Chong, Baile Zhang
Summary: This paper introduces an experimental demonstration of exploring Chern vectors in three-dimensional topological materials. The researchers used magnetically tunable photonic crystals to achieve Chern vectors and their topological surface states. The experimental results demonstrate that Chern vectors are intrinsic bulk topological invariants in three-dimensional topological materials.
Article
Engineering, Electrical & Electronic
Lingjie Du, Jianmin Zheng, Yang-Zhi Chou, Jie Zhang, Xingjun Wu, Gerard Sullivan, Amal Ikhlassi, Rui-Rui Du
Summary: Measurements of one-dimensional Coulomb drag between adjacent edge states of quantum spin Hall insulators suggest that QSH effects could be used to suppress the impact of Coulomb interactions on future nanocircuit performance. However, challenges remain in understanding and controlling the competing drag mechanisms at higher temperatures.
NATURE ELECTRONICS
(2021)
Article
Optics
Sergey K. Ivanov, Yaroslav Kartashov, Alexander Szameit, Lluis Torner, Vladimir V. Konotop
Summary: Topological insulators are physical structures that are insulators in their bulk but support currents at their edges due to topological effects. Photonic topological insulators can be created in materials with strong nonlinear response, leading to phenomena such as the formation of topological edge solitons.These solitons are supported by parametric interactions in chi((2)) nonlinear media and open new prospects for exploring frequency-mixing phenomena in photonic Floquet quadratic nonlinear media.
LASER & PHOTONICS REVIEWS
(2022)
Article
Chemistry, Physical
Georgios G. Pyrialakos, Julius Beck, Matthias Heinrich, Lukas J. Maczewsky, Nikolaos Kantartzis, Mercedeh Khajavikhan, Alexander Szameit, Demetrios N. Christodoulides
Summary: In this study, the authors present a photonic realization of Floquet topological insulators that reveal topological phases supporting both Chern and anomalous topological states. They introduce a class of bimorphic Floquet topological insulators that utilize connective chains with periodically modulated on-site potentials to reveal rich topological features in the system. Experimental results using photonic waveguide lattices show a strongly confined helical edge state that can be set into motion or halted without compromising its adherence to individual lattice sites.
Article
Multidisciplinary Sciences
Tobias Biesenthal, Lukas J. Maczewsky, Zhaoju Yang, Mark Kremer, Mordechai Segev, Alexander Szameit, Matthias Heinrich
Summary: Conventional wisdom suggests that the insulating bulk is crucial for defining the topological properties of topological insulators. However, our study shows that even without an insulating bulk, fractal topological insulators composed exclusively of edge sites can still support topologically protected edge states. Additionally, we find that light transport in our topological fractal system exhibits higher velocities compared to the corresponding honeycomb lattice.
Article
Multidisciplinary Sciences
Andrea Steinfurth, Ivor Kresic, Sebastian Weidemann, Mark Kremer, Konstantinos G. Makris, Matthias Heinrich, Stefan Rotter, Alexander Szameit
Summary: This study theoretically and experimentally demonstrates the possibility of controlling light propagation and diffraction in inhomogeneous media through non-Hermitian tailoring.
Article
Physics, Multidisciplinary
Vera Neef, Julien Pinske, Friederike Klauck, Lucas Teuber, Mark Kremer, Max Ehrhardt, Matthias Heinrich, Stefan Scheel, Alexander Szameit
Summary: When a quantum system undergoes slow changes, its state evolution depends on the trajectory in Hilbert space, known as quantum holonomy, which reveals the geometric aspects of quantum theory. Matrix-valued holonomies are challenging to implement, and identifying suitable dark states for their construction in bosonic systems is even more complicated. In this study, a representation of holonomic theory based on the Heisenberg picture is developed, and a three-dimensional quantum holonomy is experimentally realized using indistinguishable photons. The findings could open up possibilities for the experimental study of higher-dimensional non-Abelian gauge symmetries and the exploration of exotic physics on a photonic chip.
Review
Optics
Soham Saha, Ohad Segal, Colton Fruhling, Eran Lustig, Mordecai Segev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: Recent advances in ultrafast, large-modulation photonic materials have led to the potential development of photonic time crystals. This perspective discusses the promising candidates for photonic time crystals, outlining their modulation speed and depth. The challenges and possible paths to success are also analyzed.
Article
Optics
Max Ehrhardt, Sebastian Weidemann, Lukas J. Maczewsky, Matthias Heinrich, Alexander Szameit
Summary: The concept of synthetic dimension uses non-spatial degrees of freedom to mimic additional geometric dimensions, overcoming limitations in the number of effectively available dimensions. Photonics offers various technological possibilities for controlling photons and their degrees of freedom, enabling the experimental exploration of higher-dimensional physical phenomena. Mathematical mapping procedures have further enhanced the field of synthetic dimensions, allowing for higher synthetic dimensions and potential applications in quantum simulations. This article summarizes and discusses current experimental approaches for probing higher-dimensional physics using synthetic dimensions on different light-based platforms, and provides an outlook on promising future prospects in this field.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Tom A. W. Wolterink, Matthias Heinrich, Alexander Szameit
Summary: This study applies concepts from supersymmetry (SUSY) to construct two-dimensional (2D) systems with spectra identical to that of one-dimensional (1D) J(x) lattices, facilitating experimental fabrication of large-scale photonic circuits.
LASER & PHOTONICS REVIEWS
(2023)
Editorial Material
Optics
Dali Cheng, Eran Lustig, Kai Wang, Shanhui Fan
Summary: The concept of synthetic dimensions in photonics provides a versatile platform in exploring multi-dimensional physics. We propose and experimentally demonstrate a method to fully measure multi-dimensional band structures in the synthetic frequency dimension. By introducing a gauge potential into the lattice Hamiltonian, we can measure the band structure of the lattice over the entire multi-dimensional Brillouin zone. Our results reveal the properties of point-gap topology of non-Hermitian Hamiltonian in more than one dimensions.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Boquan Ren, Yaroslav V. Kartashov, Lukas J. Maczewsky, Marco S. Kirsch, Hongguang Wang, Alexander Szameit, Matthias Heinrich, Yiqi Zhang
Summary: We study linear and nonlinear higher-order topological insulators based on fractal waveguide arrays. These fractal structures have discrete rotational symmetries and multiple internal edges and corners in their optical potential landscape, and lack an insulating bulk. By systematically shifting the waveguides in the fractal arrays, we can form topological corner states at the outer corners of the array. These corner states can be efficiently excited by injecting Gaussian beams into the outer corner sites of the fractal arrays.
Article
Physics, Particles & Fields
Holger Gies, Abdol Sabor Salek
Summary: We investigate the renormalization flow of Hilbert-Palatini gravity to the lowest non-trivial order and find evidence of an asymptotically safe high-energy completion. By quantizing all degrees of freedom beyond Einstein gravity at a given order, we can track the differences between quantizing Hilbert-Palatini gravity and Einstein gravity, which are parametrized by fluctuations of an additional abelian gauge field. The critical properties of the ultraviolet fixed point of Hilbert-Palatini gravity are similar to those of the Reuter fixed point, but occur at a smaller Newton coupling and exhibit more stable higher order exponents.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Correction
Quantum Science & Technology
Julian Muenzberg, Christoph Dittel, Maxime Lebugle, Andreas Buchleitner, Alexander Szameit, Gregor Weihs, Robert Keil