Topological states realized in metamaterials have provided a versatile platform for exploring topological physics and enabling novel applications,with topolectrical circuits emerging as a prominent example.However,pre...Topological states realized in metamaterials have provided a versatile platform for exploring topological physics and enabling novel applications,with topolectrical circuits emerging as a prominent example.However,previous research in this feld has primarily focused on lumped-element implementations,while non-lumped microwave circuits remain relatively underexplored.In this work,we design and investigate a one-dimensional non-lumped Su–Schriefer–Heeger topolectrical circuit composed of copper parallel-plate transmission lines and inductors,ofering compatibility with integrated microwave applications.Full-wave microwave simulations in the 0–10 GHz range show excellent agreement with theoretical predictions.The impedance spectrum of a fveunit-cell system displays periodic resonant passbands and stopbands corresponding to bulk states,while distinct high-Q(on the order of 10^(2))topological boundary resonances(TBRs)emerge within the stopbands,indicating the presence of localized edge states.Furthermore,the TBRs vanish when the system is reconfgured into the trivial phase,providing direct evidence of its topological nature.These response characteristics make the proposed resonator a promising candidate for future microwave devices and topological circuit applications.展开更多
In two-dimensional(2D)layer-stacked materials,the twist angle between layers provides extensive freedom to explore novel physics and engineer remarkable thermal transport properties.We discovered that the cross-plane ...In two-dimensional(2D)layer-stacked materials,the twist angle between layers provides extensive freedom to explore novel physics and engineer remarkable thermal transport properties.We discovered that the cross-plane thermal conductivity of multilayer graphene can be effectively controlled by arranging the layers with two specific twist angles in a defined sequence.Disorderly aperiodic twisted graphene layers lead to the localization of phonons,substantially reducing the cross-plane thermal transport via the interference of coherent phonons.Weemployed non-equilibrium molecular dynamics simulations combined with machine learning approach,to study heat transport in the two-angle disordered multilayer stacks,and identified within the constrained structural space the optimal stacking sequence that can minimize the cross-plane thermal conductivity.Compared to pristine graphite,the optimized structure can reduce thermal conductivity by up to 80%.Through analysis of phonon transport properties across different structures,we revealed the underlying physical mechanism of phonon localization.展开更多
Identifying optical modes in chaotic cavities is crucial for exploring and understanding the physical mechanisms inside them.Compared with free spectral range estimation,the direct imaging technique has the capability...Identifying optical modes in chaotic cavities is crucial for exploring and understanding the physical mechanisms inside them.Compared with free spectral range estimation,the direct imaging technique has the capability of providing more precise mode information,but it is extremely time-consuming and susceptible to environmental perturbations.Here we report a high-speed imaging technique for visualizing field distributions in chaotic microcavities.When a silicon microdisk is excited by a femtosecond laser,free carriers are locally generated,thereby reducing the refractive index.Under a constant laser power,the spatial distribution of mode inside the silicon microdisk is proportional to its wavelength shift and can be precisely identified by comparing it with numerical simulation.With the assistance of a galvanometer,imaging a mode profile only takes a few hundred milliseconds to a few seconds,orders of magnitude faster than previous reports.The impacts of slight fabrication deviations on spectra have also been identified.展开更多
Nanoelectromechanical systems(NEMS)based on atomically-thin tungsten diselenide(WSe_(2)),benefiting from the excellent material properties and the mechanical degree of freedom,offer an ideal platform for studying and ...Nanoelectromechanical systems(NEMS)based on atomically-thin tungsten diselenide(WSe_(2)),benefiting from the excellent material properties and the mechanical degree of freedom,offer an ideal platform for studying and exploiting dynamic strain engineering and cross-scale vibration coupling in two-dimensional(2D)crystals.However,such opportunity has remained largely unexplored for WSe_(2)NEMS,impeding exploration of exquisite physical processes and realization of novel device functions.Here,we demonstrate dynamic coupling between atomic lattice vibration and nanomechanical resonances in few-layer WSe_(2)NEMS.Using a custom-built setup capable of simultaneously detecting Raman and motional signals,we accomplish cross-scale mode coupling between the THz crystal phonon and MHz structural vibration,achieving GHz frequency tuning in the atomic lattice modes with a dynamic gauge factor of 61.9,the best among all 2D crystals reported to date.Our findings show that such 2D NEMS offer great promises for exploring cross-scale physics in atomically-thin semiconductors.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11874431)the National Key R&D Program of China(Grant No.2018YFA0306800)。
文摘Topological states realized in metamaterials have provided a versatile platform for exploring topological physics and enabling novel applications,with topolectrical circuits emerging as a prominent example.However,previous research in this feld has primarily focused on lumped-element implementations,while non-lumped microwave circuits remain relatively underexplored.In this work,we design and investigate a one-dimensional non-lumped Su–Schriefer–Heeger topolectrical circuit composed of copper parallel-plate transmission lines and inductors,ofering compatibility with integrated microwave applications.Full-wave microwave simulations in the 0–10 GHz range show excellent agreement with theoretical predictions.The impedance spectrum of a fveunit-cell system displays periodic resonant passbands and stopbands corresponding to bulk states,while distinct high-Q(on the order of 10^(2))topological boundary resonances(TBRs)emerge within the stopbands,indicating the presence of localized edge states.Furthermore,the TBRs vanish when the system is reconfgured into the trivial phase,providing direct evidence of its topological nature.These response characteristics make the proposed resonator a promising candidate for future microwave devices and topological circuit applications.
基金supported by National Key Research and Development Program of China(No.2023YFB4603801)National Natural Science Foundation of China(Nos.52176173,21FAA02809)+3 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2021ZT09L227)Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110192,2022A1515010710,2023B1515040023)Fundamental Research Funds for the Central Universities(22hytd08)The calculations reported were partially performed on resources provided by the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(No.2022B1212010008).
文摘In two-dimensional(2D)layer-stacked materials,the twist angle between layers provides extensive freedom to explore novel physics and engineer remarkable thermal transport properties.We discovered that the cross-plane thermal conductivity of multilayer graphene can be effectively controlled by arranging the layers with two specific twist angles in a defined sequence.Disorderly aperiodic twisted graphene layers lead to the localization of phonons,substantially reducing the cross-plane thermal transport via the interference of coherent phonons.Weemployed non-equilibrium molecular dynamics simulations combined with machine learning approach,to study heat transport in the two-angle disordered multilayer stacks,and identified within the constrained structural space the optimal stacking sequence that can minimize the cross-plane thermal conductivity.Compared to pristine graphite,the optimized structure can reduce thermal conductivity by up to 80%.Through analysis of phonon transport properties across different structures,we revealed the underlying physical mechanism of phonon localization.
基金National Key Research and Development Program of China(2024YFB2809200)National Natural Science Foundation of China(12334016,12025402,62125501,62335005,12261131500,92250302)+2 种基金New Cornerstone Science Foundation(Xplorer Prize)Shenzhen Fundamental Research Projects(JCYJ20241202123719025,JCYJ20241202123729038)Fundamental Research Funds for the Central Universities(2022FRFK01013)。
文摘Identifying optical modes in chaotic cavities is crucial for exploring and understanding the physical mechanisms inside them.Compared with free spectral range estimation,the direct imaging technique has the capability of providing more precise mode information,but it is extremely time-consuming and susceptible to environmental perturbations.Here we report a high-speed imaging technique for visualizing field distributions in chaotic microcavities.When a silicon microdisk is excited by a femtosecond laser,free carriers are locally generated,thereby reducing the refractive index.Under a constant laser power,the spatial distribution of mode inside the silicon microdisk is proportional to its wavelength shift and can be precisely identified by comparing it with numerical simulation.With the assistance of a galvanometer,imaging a mode profile only takes a few hundred milliseconds to a few seconds,orders of magnitude faster than previous reports.The impacts of slight fabrication deviations on spectra have also been identified.
基金support from the National Science Fund for Distinguished Young Scholars(Grant No.T2325007)Opening Foundation of Hubei Key Laboratory of MicroNanoelectronic Materials and Devices(Grant No.K202307)+3 种基金National Natural Science Foundation of China(Grant Nos.62450003,62404029,62401104,U21A20459,62250073,61774029)Opening Foundation of State key laboratory of precision measuring technology and instruments(Tianjin University)(Grant No.Pilab2411)China Postdoctoral Science Foundation(Grant Nos.GZB20230107,GZB20240109)Natural Science Foundation of Sichuan Province(Grant Nos.2024NSFSC1408,2024NSFSC1430).
文摘Nanoelectromechanical systems(NEMS)based on atomically-thin tungsten diselenide(WSe_(2)),benefiting from the excellent material properties and the mechanical degree of freedom,offer an ideal platform for studying and exploiting dynamic strain engineering and cross-scale vibration coupling in two-dimensional(2D)crystals.However,such opportunity has remained largely unexplored for WSe_(2)NEMS,impeding exploration of exquisite physical processes and realization of novel device functions.Here,we demonstrate dynamic coupling between atomic lattice vibration and nanomechanical resonances in few-layer WSe_(2)NEMS.Using a custom-built setup capable of simultaneously detecting Raman and motional signals,we accomplish cross-scale mode coupling between the THz crystal phonon and MHz structural vibration,achieving GHz frequency tuning in the atomic lattice modes with a dynamic gauge factor of 61.9,the best among all 2D crystals reported to date.Our findings show that such 2D NEMS offer great promises for exploring cross-scale physics in atomically-thin semiconductors.
