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Effects of quantum interference in multiwaveguide systems bridged by Jaynes-Cummings emitters

Physical Review A 2022年第5期105卷 053712-053712页

作者： Zhen-Rui Li Junhua Dong Yafang Xu Bingsuo Zou Yongyou Zhang Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China College of Physics Science and Technology Yangzhou University Yangzhou 225002 China MOE and Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials School of Physical Science and Technology Guangxi University Nanning 530004 China

quantum interference, responsible for a number of resonant optical phenomena, always intrigues researchers because of its application in optical devices. This work studies it in multiwaveguide systems bridged by Jaynes-Cummings emitters (JCEs) based on the scattering matrix theory. Two types of quantum interference are distinguished here. The first is between the incident wave and those scattered from the JCEs, while the second is only among those scattered waves. The first type leads to the two transmission valleys at the two eigenfrequencies of the JCEs in single-waveguide–single-JCE coupled systems. However, the second type is responsible for the narrow transmission peaks in single-waveguide–multi-JCE coupled systems, locating in the above transmission valleys. This work first shows the properties of the second type of quantum interference in detail and then discusses its two applications. On the one hand, the second type of quantum interference can be used to tailor the transmission spectra to achieve the electromagnetically-induced-transparency-like line shapes with a large group delay. On the other hand, it can also lead to the single-photon jumping between two certain waveguides with a nearly 100% chance in multiwaveguide systems by switching on or off some of the couplings of the JCEs to the waveguides. These applications with small peak widths commonly require a small loss and might have potential in quantum informatics.

关键词： Coherent control quantum interference effects Scattering theory Waveguide arrays

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Single pair of multi-Weyl points in nonmagnetic crystals

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Physical Review B 2022年第19期106卷 195129-195129页

作者： Xiaotian Wang Feng Zhou Zeying Zhang Weikang Wu Zhi-Ming Yu Shengyuan A. Yang School of Physical Science and Technology Southwest University Chongqing 400715 China College of Mathematics and Physics Beijing University of Chemical Technology Beijing 100029 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore 487372 Singapore Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China

Topological semimetal states having the minimal number, i.e., only a single pair, of Weyl points are desirable for the study of effects associated with chiral topological charges. So far, the search for such states is focused on magnetic spinful systems. Here, we find that nonmagnetic spinless systems can host a class of single-pair-Weyl-point (SP-WP) states, where the two Weyl points are located at two high-symmetry time-reversal-invariant momenta. We identify 38 candidate space groups that host such states, and we show that the chiral charge of each Weyl point must be an even integer, representing a multi-Weyl point. Besides achieving the minimal number, the two points in SP-WP states are far separated in momentum space, making the physics of each individual point better exposed. The large separation combined with the even topological charge lead to extended surface Fermi loops with a noncontractible winding topology on the surface Brillouin zone torus, distinct from conventional Weyl semimetals. We confirm our proposal in the phonon spectra of two concrete materials TlBO2 and KNiIO6. Our finding applies to a wide range of systems, including electronic, phononic, and various artificial systems. It offers a new direction for the search of ideal platforms to study chiral particles.

关键词： Acoustic phonons Phonons Symmetry protected topological states Topological phases of matter Topological materials Weyl semimetal Density functional theory k dot p method

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Tunable magneto-optical effect, anomalous Hall effect, and anomalous Nernst effect in the two-dimensional room-temperature ferromagnet 1T−CrTe2

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Physical Review B 2021年第2期103卷 024436-024436页

作者： Xiuxian Yang Xiaodong Zhou Wanxiang Feng Yugui Yao Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement Ministry of Education School of Physics Beijing Institute of Technology Beijing 100081 China Kunming Institute of Physics Kunming 650223 China

Utilizing first-principles density functional theory calculations together with group theory analyses, we systematically investigate the spin-order-dependent magneto-optical effect (MOE), anomalous Hall effect (AHE), and anomalous Nernst effect (ANE) in the recently discovered two-dimensional room-temperature ferromagnet 1T−CrTe2. We find that the spin prefers an in-plane direction by the magnetocrystalline anisotropy energy calculations. The MOE, AHE, and ANE display a period of 2π/3 when the spin rotates within the atomic plane, and they are forbidden if a mirror plane perpendicular to the spin direction exists. By reorienting the spin from the in-plane to out-of-plane direction, the MOE, AHE, and ANE are enhanced by around one order of magnitude. Moreover, we establish the layer-dependent magnetic properties of multilayer 1T−CrTe2 and predict antiferromagnetism and ferromagnetism for bilayer and trilayer 1T−CrTe2, respectively. The MOE, AHE, and ANE are prohibited in antiferromagnetic bilayer 1T−CrTe2 due to the existence of the space-time inversion symmetry, whereas all of them are activated in ferromagnetic trilayer 1T−CrTe2 and are significantly enhanced compared to those of monolayer 1T−CrTe2. Our results show that the magneto-optical and anomalous transports proprieties of 1T−CrTe2 can be effectively modulated by altering spin direction and layer number.

关键词： Anomalous Hall effect Magneto-optical effect Nernst effect Magnetic multilayers First-principles calculations

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Giant Second-Order Nonlinear Hall Effect in Twisted Bilayer Graphene

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Physical Review Letters 2022年第18期129卷 186801-186801页

作者： Junxi Duan Yu Jian Yang Gao Huimin Peng Jinrui Zhong Qi Feng Jinhai Mao Yugui Yao Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100086 China Department of Physics University of Science and Technology of China Hefei Anhui 230026 China School of Physical Sciences and CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100049 China

In the second-order response regime, the Hall voltage can be nonzero without time-reversal symmetry breaking but inversion symmetry breaking. Multiple mechanisms contribute to the nonlinear Hall effect. The disorder-related contributions can enter the NLHE in the leading role, but experimental investigations are scarce, especially the exploration of the contributions from different disorder sources. Here, we report a giant nonlinear response in twisted bilayer graphene, dominated by disorder-induced skew scattering. The magnitude and direction of the second-order nonlinearity can be effectively tuned by the gate voltage. A peak value of the second-order Hall conductivity reaching 8.76 μm SV−1 is observed close to the full filling of the moiré band, four order larger than the intrinsic contribution detected in WTe2. The scaling shows that the giant second-order nonlinear Hall effect in twisted bilayer graphene stems from the collaboration of the static (impurities) and dynamic (phonons) disorders. It is mainly determined by the impurity skew scattering at 1.7 K. The phonon skew scattering, however, has a much larger coupling coefficient, and becomes comparable to the impurity contribution as the temperature rises. Our observations provide a comprehensive experimental understanding of the disorder-related mechanisms in the nonlinear Hall effect.

关键词： Hall effect Transport phenomena Twisted bilayer graphene Hall bar

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Strong magneto-optical effect and anomalous transport in the two-dimensional van der Waals magnets FenGeTe2 (n=3, 4, 5)

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Physical Review B 2021年第10期104卷 104427-104427页

作者： Xiuxian Yang Xiaodong Zhou Wanxiang Feng Yugui Yao Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China Kunming Institute of Physics Kunming 650223 China

Two-dimensional ferromagnetic materials have recently been attracted much attention mainly due to their promising applications toward multifunctional devices, e.g., microelectronics, spintronics, and thermoelectric devices. Utilizing the first-principles calculations together with the group theory analysis, we systematically investigate the magnetocrystalline anisotropy energy, magneto-optical effect, and anomalous transport properties (including anomalous Hall, Nernst, and thermal Hall effects) of monolayer and bilayer FenGeTe2 (n=3, 4, 5). The monolayer FenGeTe2 (n=3, 4, 5) exhibits the out-of-plane, in-plane, and in-plane ferromagnetic orders with considerable magnetocrystalline anisotropy energies of −3.17, 4.42, and 0.58 meV/f.u., respectively. Ferromagnetic order is predicted in bilayer Fe4GeTe2 while antiferromagnetic order is preferred in bilayer Fe3GeTe2 and Fe5GeTe2. The group theory analysis reveals that in addition to monolayer ferromagnetic FenGeTe2 (n=3, 4, 5), the magneto-optical and anomalous transport phenomena surprisingly exist in bilayer antiferromagnetic Fe5GeTe2, which rare in realistic collinear antiferromagnets. If spin magnetic moments of monolayer and bilayer FenGeTe2 are reoriented from the in-plane to out-of-plane direction, then the magneto-optical and anomalous transport properties are enhanced significantly, presenting strong magnetic anisotropy. We also demonstrate that the anomalous Hall effect decreases with the temperature increases. The gigantic anomalous Nernst and thermal Hall effects are found in monolayer and bilayer ferromagnetic FenGeTe2, and the largest anomalous Nernst and thermal Hall conductivities, respectively, of −3.31 A/Km and 0.22 W/Km at 130 K are observed in bilayer ferromagnetic Fe4GeTe2. In particular, bilayer antiferromagnetic Fe5GeTe2 exhibits large zero-temperature anomalous Hall conductivity of 2.63 e2/h as well as anomalous Nernst and thermal Hall conductivities of 2.76 A/Km and 0.10 W/Km at 130 K, respecti

关键词： Anomalous Hall effect Faraday effect Kerr effect Magnetic anisotropy Magnetic order Spintronics 2-dimensional systems

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quantum transport evidence of boundary states and Lifshitz transition in Bi4Br4

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Physical Review B 2022年第7期106卷 075206-075206页

作者： Dong-Yun Chen Dashuai Ma Junxi Duan Dong Chen Haiwen Liu Junfeng Han Yugui Yao Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement Ministry of Education School of Physics Beijing Institute of Technology Beijing 100081 China Yangtze Delta Region Academy of Beijing Institute of Technology Jiaxing 314000 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China College of Physics Qingdao University Qingdao 266071 China Institute for Structure and Function & Department of Physics Chongqing University Chongqing 400044 China Center for Advanced Quantum Studies Department of Physics Beijing Normal University Beijing 100875 China

The quasi-one-dimensional van der Waals compound Bi4Br4 was recently found to be a promising high-order topological insulator with exotic electronic states. In this paper, we study the electrical transport properties of Bi4Br4 bulk crystals. Two electron-type samples with different electron concentrations are investigated. Both samples exhibit a saturation behavior of resistivity in low temperature. In the low-concentration sample, two-dimensional quantum oscillations are clearly observed in the magnetoresistance measurements, which are attributed to the band-bending-induced surface state on the (001) surface. In the high-concentration sample, the angular magnetoresistance exhibits two pairs of symmetrical sharp valleys with an angular difference close to the angle between the crystal planes (001) and (100). The additional valley can be explained by the contribution of the boundary states on the (100) facet. Besides, Hall measurements at low temperatures reveal an anomalous decrease of electron concentration with increasing temperature, which can be explained by the temperature-induced Lifshitz transition. These results shed light on the abundant boundary state transport signals and the temperature-induced Lifshitz transition in Bi4Br4.

关键词： Hall effect Magnetoresistance Surface states Topological insulators quantum oscillation techniques

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One-way Einstein-Podolsky-Rosen steering beyond qubits

arXiv

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arXiv 2022年

作者： Zeng, Qiang Beijing Academy of Quantum Information Sciences Beijing100193 China Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement of Ministry of Education School of Physics Beijing Institute of Technology Beijing100081 China Centre for Quantum Dynamics Griffith University BrisbaneQLD4111 Australia

quantum steering has been exploited as an important resource in modern quantum information processing. Owing to its directional nature, some quantum states that are asymmetric under the exchange of parties have been found to manifest steering only in specific direction, thus called one-way steering. Existing works focused on one-way steering in systems of qubits. Here we propose a family of two-party states that are one-way steerable in systems of d-dimension. In particular, we validate the one-way steerability of the states for d = 3, and demonstrate how one-way steering parameter space manifests in two-qutrit system. A general numerical approach for characterizing higher-dimensional one-way steering is provided. Moreover, we develop a method to characterize one-way steering with the experimental loss taken into account, with which the tradeoff relation between losses and measurement settings in steering test in higher-dimensional system is investigated. Our loss-counted model works for finite-dimensional system with finite measurement settings. © 2022, CC BY.

关键词： quantum optics

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Ab initio four-band Wannier tight-binding model for generic twisted graphene systems

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Physical Review B 2021年第8期104卷 L081403-L081403页

作者： Jin Cao Maoyuan Wang Shi-Feng Qian Cheng-Cheng Liu Yugui Yao Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China International Center for Quantum Materials School of Physics Peking University Beijing 100871 China

The newly realized twisted graphene systems such as twisted bilayer graphene (TBG), twisted double bilayer graphene (TDBG), and twisted trilayer graphene (TTG) have attracted widespread attention. Therefore, a simple and exact model of the systems is urgent and vital for further study. Here, we construct the symmetry-adapted localized Wannier functions and the corresponding ab initio minimal two-valley four-band effective tight-binding models for generic twisted graphene systems with small twist angle. Such a two-valley model circumvents the Wannier obstruction caused by the fragile topology in the one-valley model. The real-space valley operator is introduced to explicitly describe the valley Uv(1) symmetry. Each symmetry-adapted Wannier orbital shows a peculiar three-peak form with its maximum at AA spots and its center at AB or BA spots. An extended Hubbard model is also given and the related interaction parameters are presented explicitly. We provide an approach to systematically build the Wannier tight-binding model for generic twisted graphene systems. Our model provides a firm basis for further study of the many-body effects in these systems.

关键词： Electronic structure Graphene First-principles calculations Wannier function methods

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Adaptable Invisibility Management Using Kirigami-Inspired Transformable Metamaterials

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Research 2021年第1期2021卷 1034-1044页

作者： He-Xiu Xu Mingzhao Wang Guangwei Hu Shaojie Wang Yanzhao Wang Chaohui Wang Yixuan Zeng Jiafang Li Shuang Zhang Wei Huang Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China Institute of Flexible Electronics Northwestern Polytechnical UniversityXi’an 710072China Department of Electrical and Computer Engineering National University of SingaporeSingaporeSingapore 117583 Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)Beijing 100081China School of Physics Beijing Institute of TechnologyBeijing 100081China Department of Physics University of Hong KongHong KongChina Department of Electronic&Electrical Engineering University of Hong KongHong KongChina

Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in an on-demand ***,kirigami technique,affording versatile and unconventional structural transformation,has been introduced to endow metamaterials with the capability of controlling EM waves in a reconfigurable ***,we report for a kirigami-inspired sparse meta-architecture,with structural density of 1.5%in terms of the occupation space,for adaptive invisibility based on independent operations of frequency,bandwidth,and *** on the general principle of dipolar management via structural reconstruction of kirigami-inspired meta-architectures,we demonstrate reconfigurable invisibility management with abundant EM functions and a wide tuning range using three enantiomers(A,B,and C)of different geometries characterized by the folding angleβ.Our strategy circumvents issues of limited abilities,narrow tuning range,extreme condition,and high cost raised by available reconfigurable metamaterials,providing a new avenue toward multifunctional smart devices.

关键词： tuning visibility smart

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Visualization of topological shear polaritons in gypsum thin films

arXiv

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arXiv 2025年

作者： Díaz-Núñez, Pablo Lanza, Christian Wang, Ziwei Kravets, Vasyl G. Duan, Jiahua Álvarez-Cuervo, José Martín-Luengo, Aitana Tarazaga Grigorenko, Alexander N. Yang, Qian Paarmann, Alexander Caldwell, Joshua Alonso-González, Pablo Mishchenko, Artem Department of Physics and Astronomy University of Manchester Manchester United Kingdom National Graphene Institute University of Manchester Manchester United Kingdom Department of Physics University of Oviedo Oviedo Spain El Entrego Spain Center for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement [MOE School of Physics Beijing China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic System Beijing Beijing Institute of Technology Beijing China Fritz Haber Institute of the Max Planck Society Berlin Germany Department of Mechanical engineering Vanderbilt University Nashville United States

Low symmetry crystals have recently emerged as a platform for exploring novel light-matter interactions in the form of hyperbolic shear polaritons. These excitations exhibit unique optical properties such as frequency-dispersive optical axes and asymmetric light propagation and energy dissipation, which arise from the presence of non-orthogonal resonances. However, only non-vdW materials have been demonstrated to support hyperbolic shear polaritons, limiting their exotic properties and potential applications. Here we introduce for the first time novel shear phenomena in low symmetry crystal thin films by demonstrating the existence of elliptical and canalized shear phonon polaritons in gypsum, an exfoliable monoclinic sulphate mineral. Our results unveil a topological transition from hyperbolic shear to elliptical shear polaritons, passing through a canalization regime with strong field confinement. Importantly, we observe a significant slowdown of group velocity, reaching values as low as 0.0005c, highlighting the potential of gypsum for "slow light" applications and extreme light-matter interaction control. These findings expand the application scope of low-symmetry crystals with the benefits that an exfoliable material provides, such as stronger field confinement, tunability, and versatility for its incorporation in complex photonic devices that might unlock new optical phenomena at the nanoscale. Copyright © 2025, The Authors. All rights reserved.

关键词： Crystal symmetry

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