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On the topological surface states of the intrinsic magnetic topological insulator Mn-Bi-Te family

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National science Review 2024年第2期11卷 50-64页

作者： Yuan Wang Xiao-Ming Ma Zhanyang Hao Yongqing Cai Hongtao Rong Fayuan Zhang Weizhao Chen Chengcheng Zhang Junhao Lin Yue Zhao Chang Liu Qihang Liu Chaoyu Chen Shenzhen Institute for quantum science and Engineering(SIQSE)and Department of Physics Southern University of Science and Technology(SUSTech)

We review recent progress in the electronic structure study of intrinsic magnetic topological insulators（MnBi2Te4）·（Bi2Te3）n（n = 0, 1, 2, 3） family. Specifically, we focus on the ubiquitously（nearly）gapless behavior of the topological Dirac surface state observed by photoemission spectroscopy, even though a large Dirac gap is expected because of surface ferromagnetic order. The dichotomy between experiment and theory concerning this gap behavior is perhaps the most critical and puzzling question in this frontier. We discuss various proposals accounting for the lack of magnetic effect on the topological Dirac surface state, which are mainly categorized into two pictures, magnetic reconfiguration and topological surface state redistribution. Band engineering towards opening a magnetic gap of topological surface states provides great opportunities to realize quantized topological transport and axion electrodynamics at higher temperatures.

关键词： intrinsic magnetic topological insulator topological surface states magnetic gap magnetic reconfiguration topological surface state redistribution van der Waals spacing expansion

quantum key distribution over a mimicked dynamic-scattering channel

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science China(Information sciences) 2024年第4期67卷 323-330页

作者： Qi-Hang LU Fang-Xiang WANG Wei CHEN Hai-Yang FU Yin-Jie LU Shuang WANG De-Yong HE Zhen-Qiang YIN Guang-Can GUO Zheng-Fu HAN CAS Key Laboratory of quantum Information University of Science and Technology of China CAS Center for Excellence in quantum Information and quantum Physics University of Science and Technology of China Hefei National Laboratory University of Science and Technology of China

Free-space quantum key distribution(QKD) plays an important role in the global quantum network. However, free space channels suffer from the atmospheric turbulence and scattering effects of haze,fog, and dust, which significantly weaken the performance of QKD or even block the secure quantum link.Here, we prove the performance of QKD over a dynamic scattering channel can be enhanced significantly using a fast wavefront shaping technique. The system achieves on average 10-dB enhancement of quantum transmission efficiency and establishes a secure quantum link for QKD. Our work demonstrates the feasibility of QKD through free-space dynamic scattering channels and enhances the deployment capability of complex-channel QKD system.

关键词： quantum key distribution free space channel channel turbulence channel scattering wavefront shaping

Topological magnetoelectric response in ferromagnetic axion insulators

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National science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen Institute for quantum science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key Laboratory of Advanced quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key Laboratory for Computational science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological phenomena.However,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface states.Here,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the TME.In the designed triangular prism geometry,all the surface states are magnetically gapped.Under a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in parallel.Thus,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric field.Our work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

Progress on the antiferromagnetic topological insulator MnBi2Te4

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National science Review 2024年第2期11卷 33-49页

作者： Shuai Li Tianyu Liu Chang Liu Yayu Wang Hai-Zhou Lu X.C.Xie Hefei National Laboratory International Center for quantum Materials School of Physics Peking University Institute for Nanoelectronic Devices and quantum Computing Fudan University Department of Physics Harbin Institute of Technology Shenzhen Institute for quantum science and Engineering and Department of Physics Southern University of Science and Technology(SUSTech) quantum science Center of Guangdong-Hong Kong-Macao Greater Bay Area(Guangdong) Shenzhen Key Laboratory of quantum science and Engineering International quantum Academy Beijing Academy of quantum Information sciences Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-Nano Devices Department of Physics Renmin University of China State Key Laboratory of Low Dimensional quantum Physics Department of PhysicsTsinghua University Frontier science Center for quantum Information

Topological materials, which feature robust surface and/or edge states, have now been a research focus in condensed maTher physics. They represent a new class of materials exhibiting nontrivial topological phases,and provide a platform for exploring exotic transport phenomena, such as the quantum anomalous Hall effect and the quantum spin Hall effect. Recently, magnetic topological materials have attracted considerable interests due to the possibility to study the interplay between topological and magnetic orders.In particular, the quantum anomalous Hall and axion insulator phases can be realized in topological insulators with magnetic order. MnBi2Te4, as the first intrinsic antiferromagnetic topological insulator discovered, allows the examination of existing theoretical predictions; it has been extensively studied, and many new discoveries have been made. Here we review the progress made on MnBi2Te4from both experimental and theoretical aspects. The bulk crystal and magnetic structures are surveyed first, followed by a review of theoretical calculations and experimental probes on the band structure and surface states, and a discussion of various exotic phases that can be realized in MnBi2Te4. The properties of MnBi2Te4thin films and the corresponding transport studies are then reviewed, with an emphasis on the edge state transport. Possible future research directions in this field are also discussed.

关键词： MnBi2Te4 magnetic topological insulator antiferromagnetic quantum anomalous Hall effect axion insulator

Robust enhancement of valley polarization and quantum yield in composition grading lateral heterostructure of MoS2-WS2 monolayer

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Progress in Natural science:Materials International 2024年第1期34卷 187-193页

作者： Mengke Kang Cheng Zhang Congpu Mu Kun Zhai Tianyu Xue Bochong Wang Fusheng Wen Yingchun Cheng Jianyong Xiang Jun-Feng Dai Anmin Nie Zhongyuan Liu Center for High Pressure science State Key Laboratory of Metastable Materials Science and Technology Yanshan University Shenzhen Institute for quantum science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen Key Laboratory of quantum science and Engineering

Valley degeneracy can be broken owing to the strong spin-orbit coupling in two-dimensional transition metal dichalcogenides（2D-TMDCs）. Valley-dependent interaction of carriers in TMDCs with different circular polarizations of light offers valley degree-of-freedom besides charge and spin to carry information. Thus, bandgap engineering of 2D-TMDCs plays a critical role in developing practical valleytronic devices. Hereby, we demonstrate a great enhancement in quantum yield as well as polarization of monolayer MoS2achieved by gradually alloying W atoms in MoS2. By appropriately setting a time offset between the evaporation of MoO3and WO3precursors during chemical vapor deposition, a compositionally graded heterostructure of MoS2-WS2monolayer can be readily grown at large scale. Raman and transmission electron microscopy measurements demonstrate that the interface possesses a steep gradient in composition, spanning from MoS2to WS2over a length ～2 μm.Compared to pure monolayer MoS2, the photoluminescence intensity at the compositionally graded interface of Mo1-xWxS2was observed to increase by a factor of 16 owing to the effective separation of photogenerated carriers by the built-in electric field. Particularly, a remarkably high polarization of 70% at 16 K is demonstrated for the compositionally graded interface of Mo1-xWxS2, which is ～1.4 times larger than that in MoS2and is attributed to the combined effect of the alloyed structure and graded bandgap. Such an engineering scheme with a graded bandgap offers new approach for the development of high-efficiency valleytronics devices.

关键词： Transition metal dichalcognide monolayer Compositionally graded in-plane heterostructure Chemical vapor deposition Valley polarization quantum yield

Measuring small longitudinal phase shifts via weak measurement amplification

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Chinese Physics B 2024年第3期33卷 105-111页

作者：徐凯胡晓敏胡孟军王宁宁张超黄运锋柳必恒李传锋郭光灿张永生 CAS Key Laboratory of quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center For Excellence in quantum Information and quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Beijing Academy of quantum Information sciences Beijing 100193China

Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.

关键词： weak measurement phase estimation quantum optics

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Dynamical switchable quantum nonreciprocity induced by off-resonant chiral two-photon driving

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science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 31-37页

作者： Da-Wei Liu Zi-Hao Li Shi-Lei Chao Ying Wu Liu-Gang Si School of Physics and Institute for quantum science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

Optical nonreciprocity,which refers to the direction-dependent emission,scattering and absorption of photons,plays a very important role in quantum engineering and quantum information processing.Here,we propose an all-optical approach to achieve the optical dynamical switchable quantum nonreciprocity by an off-resonant chiral two-photon driving in a single microring cavity,which differs from the conventional nonreciprocal schemes.It is shown that the optical field with time-dependent statistical properties can be generated and the nonreciprocity flips periodically,with switchable photon blockade and photon-induced tunneling effects.We find that the dynamical system is robust and immune to the parameter variations,which loosens the parameter range of system.Meanwhile,the time window for one-way quantum information is sufficiently wide and tunable.Our work opens a new idea for the current quantum nonreciprocal research,which can facilitate a memory functionality and be used for future inmemory superconducting quantum compute.The other nonreciprocal quantum devices,i.e.,dynamical switchable nonreciprocal squeezing and entanglement,may be inspired by our method,which is expected to have important applications in future quantum technology.

关键词： dynamical switchable nonreciprocity single-photon source chiral two-photon driving

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Maxwell Demon and Einstein–Podolsky–Rosen Steering

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Chinese Physics Letters 2024年第5期41卷 12-16页

作者：胡孟军胡晓敏张永生 Beijing Academy of quantum Information sciences Beijing 100193China Laboratory of quantum Information University of Science and Technology of ChinaHefei 230026China Synergetic Innovation Center of quantum Information and quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Research of Maxwell demon and quantum entanglement is important because of its foundational significance in physics and its potential applications in quantum information. Previous studies on the Maxwell demon have primarily focused on thermodynamics, taking into account quantum correlations. Here we consider from another perspective and ask whether quantum non-locality correlations can be simulated by performing work. The Maxwell demon-assisted Einstein–Podolsky–Rosen(EPR) steering is thus proposed, which implies a new type of loophole. The application of Landauer's erasure principle suggests that the only way to close this loophole during a steering task is by continuously monitoring the heat fluctuation of the local environment by the participant.We construct a quantum circuit model of Maxwell demon-assisted EPR steering, which can be demonstrated by current programmable quantum processors, such as superconducting quantum computers. Based on this quantum circuit model, we obtain a quantitative formula describing the relationship between energy dissipation due to the work of the demon and quantum non-locality correlation. The result is of great physical interest because it provides a new way to explore and understand the relationship between quantum non-locality, information, and thermodynamics.

关键词： quantum Maxwell Einstein

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A von-Neumann-like photonic processor and its application in studying quantum signature of chaos

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Light(science & Applications) 2024年第4期13卷 672-681页

作者： Shang Yu Wei Liu Si-Jing Tao Zhi-Peng Li Yi-Tao Wang Zhi-Peng Zhong Raj BPatel Yu Meng Yuan-Ze Yang Zhao-An Wang Nai-Jie Guo Xiao-Dong Zeng Zhe Chen Liang Xu Ning Zhang Xiao Liu Mu Yang Wen-Hao Zhang Zong-Quan Zhou Jin-Shi Xu Jian-Shun Tang Yong-Jian Han Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of quantum Information University of Science and Technology of ChinaHefei 230026China. CAS Center for Excellence in quantum Information and quantum Physics University of Science and Technology of ChinaHefei 230026China. Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China. Research Center for quantum Sensing Zhejiang LabHangzhou 310000China. quantum Optics and Laser science Blackett LaboratoryImperial College LondonPrince Consort RdLondon SW72AZUK. Clarendon Laboratory Department of PhysicsOxford UniversityParks Road OX13PUOxfordUK

Photonic quantum computation plays an important role and offers unique advantages.Two decades after the milestone work of Knill-Laflamme-Milburn,various architectures of photonic processors have been proposed,and quantum advantage over classical computers has also been demonstrated.It is now the opportune time to apply this technology to real-world applications.However,at current technology level,this aim is restricted by either programmability in bulk optics or loss in integrated optics for the existing architectures of processors,for which the resource cost is also a problem.Here we present a von-Neumann-like architecture based on temporal-mode encoding and looped structure on table,which is capable of multimode-universal programmability,resource-efficiency,phasestability and software-scalability.In order to illustrate these merits,we execute two different programs with varying resource requirements on the same processor,to investigate quantum signature of chaos from two aspects:the signature behaviors exhibited in phase space(13 modes),and the Fermi golden rule which has not been experimentally studied in quantitative way before(26 modes).The maximal program contains an optical interferometer network with 1694 freely-adjustable phases.Considering current state-of-the-art,our architecture stands as the most promising candidate for real-world applications.

关键词： quantum signature chaos