In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-st...In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-step hydrothermal reaction on the surfaces of MFe_(2)O_4 nanospheres with the certain amounts of Mo and Se sources.With increasing the amounts of Mo and Se sources,the obtained core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)MCNCs with the enhanced content of MoSe_(2)and improved flower-like geometry morphology could be produced on a large scale.The obtained results revealed that the as-prepared samples displayed improved comprehensive microwave absorption properties(CMAPs)with the increased amounts of Mo and Se sources.The as-prepared CoSe_(2)/FeSe_(2)@MoSe_(2)and NiSe_(2)/FeSe_(2)@MoSe_(2)MCNCs with the well-defined flower-like morphology could simultaneously present the outstanding CMAPs in terms of strong absorption capability,wide absorption bandwidth,and thin matching thicknesses,which mainly originated from the conduction loss and flower-like geometry morphology.Therefore,the findings not only develop the very desirable candidates for high-performance microwave absorption materials but also pave a new way for optimizing the CMAPs through tailoring morphology engineering.展开更多
Gradient heterostructure is one of fundamental interfaces and provides an effective platform to achieve gradually changed properties in mechanics,optics,and electronics.Among different types of heterostructures,the gr...Gradient heterostructure is one of fundamental interfaces and provides an effective platform to achieve gradually changed properties in mechanics,optics,and electronics.Among different types of heterostructures,the gradient one may provide multiple resistive states and immobilized conductive fila-ments,offering great prospect for fabricating memristors with both high neuromorphic computation capability and repeatability.Here,we invent a memristor based on a homologous gradient heterostructure(HGHS),compris-ing a conductive transition metal dichalcogenide and an insulating homolo-gous metal oxide.Memristor made of Ta–TaS_(x)O_(y)–TaS 2 HGHS exhibits continuous potentiation/depression behavior and repeatable forward/backward scanning in the read-voltage range,which are dominated by multi-ple resistive states and immobilized conductive filaments in HGHS,respec-tively.Moreover,the continuous potentiation/depression behavior makes the memristor serve as a synapse,featuring broad-frequency response(10^(-1)–10^(5) Hz,covering 106 frequency range)and multiple-mode learning(enhanced,depressed,and random-level modes)based on its natural and moti-vated forgetting behaviors.Such HGHS-based memristor also shows good unifor-mity for 5?7 device arrays.Our work paves a way to achieve high-performance integrated memristors for future artificial neuromorphic computation.展开更多
Constructing composites with heterogeneous structure and dual loss mechanism shows great potential in designing microwave absorbers.In this work,two-dimensional cobalt and nickel alloys@mesoporous carbon(CoNi@MC)compo...Constructing composites with heterogeneous structure and dual loss mechanism shows great potential in designing microwave absorbers.In this work,two-dimensional cobalt and nickel alloys@mesoporous carbon(CoNi@MC)composites were constructed via using CoNi layered double hydroxide@mesoporous polydopamine(CoNi LDH@MPDA)as sacrifice template.During the pyrolysis process,the MPDA is transformed into mesoporous carbon coated the surface of CoNi LDH that is further reduced to CoNi alloys.The mesoporous structure is conducive to the multi-reflection of electromagnetic waves and facilitates optimizing impedance matching.Heterogeneous interfaces between CoNi alloys and mesoporous carbon induce interface polarization.Multiple attenuation mechanism promotes the electromagnetic waves conversion.The maximum reflection loss of CoNi@MC composite is−70.86 dB and the widest effective absorption bandwidth is 7.74 GHz covering almost the entire Ku band.This strategy will be a guidance for designing electromagnetic absorbers.展开更多
The manipulation of photons is a key technology for obtaining optical quantum information.In this study,we present a phase-modulated optomechanical system comprising two coupled cavity resonators and illustrate the ph...The manipulation of photons is a key technology for obtaining optical quantum information.In this study,we present a phase-modulated optomechanical system comprising two coupled cavity resonators and illustrate the phase-controlled photon blockade in the system.The coupling phase of the cavities reveals the interference of photons and introduces an unconventional photon-blockade effect.We also study the influence of the energy level fineness on the photon blockade and resonant frequency of the mechanical mode.Numerical simulations demonstrate that photon blockade can occur over a wide range of system parameters.These results have several implications for understanding the role of the state phase in quantum cavity optomechanics and provide a promising method for the realization of optomechanical quantum devices using photon blockade.展开更多
We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found ...We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.展开更多
基金financially supported by the Fund of Fok Ying Tung Education Foundationthe Major Research Project of innovative Group of Guizhou province(2018–013)+2 种基金the Open Fund from Henan University of Science and Technologythe National Science Foundation of China(Nos.11964006 and 11774156)the Foundation of the National Key Project for Basic Research(No.2012CB932304)。
文摘In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-step hydrothermal reaction on the surfaces of MFe_(2)O_4 nanospheres with the certain amounts of Mo and Se sources.With increasing the amounts of Mo and Se sources,the obtained core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)MCNCs with the enhanced content of MoSe_(2)and improved flower-like geometry morphology could be produced on a large scale.The obtained results revealed that the as-prepared samples displayed improved comprehensive microwave absorption properties(CMAPs)with the increased amounts of Mo and Se sources.The as-prepared CoSe_(2)/FeSe_(2)@MoSe_(2)and NiSe_(2)/FeSe_(2)@MoSe_(2)MCNCs with the well-defined flower-like morphology could simultaneously present the outstanding CMAPs in terms of strong absorption capability,wide absorption bandwidth,and thin matching thicknesses,which mainly originated from the conduction loss and flower-like geometry morphology.Therefore,the findings not only develop the very desirable candidates for high-performance microwave absorption materials but also pave a new way for optimizing the CMAPs through tailoring morphology engineering.
基金We thank the financial support from the National Science Fund for Distinguished Young Scholars(No.52125309)the National Natural Science Foundation of China(Nos.51991343,52188101,51920105002,and 51991340)+1 种基金Guang-dong Innovative and Entrepreneurial Research Team Pro-gram(No.2017ZT07C341)the Shenzhen Basic Research Program(Nos.JCYJ20200109144616617 and JCYJ20200109144620815)。
文摘Gradient heterostructure is one of fundamental interfaces and provides an effective platform to achieve gradually changed properties in mechanics,optics,and electronics.Among different types of heterostructures,the gradient one may provide multiple resistive states and immobilized conductive fila-ments,offering great prospect for fabricating memristors with both high neuromorphic computation capability and repeatability.Here,we invent a memristor based on a homologous gradient heterostructure(HGHS),compris-ing a conductive transition metal dichalcogenide and an insulating homolo-gous metal oxide.Memristor made of Ta–TaS_(x)O_(y)–TaS 2 HGHS exhibits continuous potentiation/depression behavior and repeatable forward/backward scanning in the read-voltage range,which are dominated by multi-ple resistive states and immobilized conductive filaments in HGHS,respec-tively.Moreover,the continuous potentiation/depression behavior makes the memristor serve as a synapse,featuring broad-frequency response(10^(-1)–10^(5) Hz,covering 106 frequency range)and multiple-mode learning(enhanced,depressed,and random-level modes)based on its natural and moti-vated forgetting behaviors.Such HGHS-based memristor also shows good unifor-mity for 5?7 device arrays.Our work paves a way to achieve high-performance integrated memristors for future artificial neuromorphic computation.
基金the National Natural Science Foundation of China(No.51772177)the Shaanxi Science&Technology Co-ordination&Innovation Project of China(No.2017TSCXL-GY-08-05)the Science Fund for Distinguished Young Scholars of Shaanxi Province(No.2018JC-029).
文摘Constructing composites with heterogeneous structure and dual loss mechanism shows great potential in designing microwave absorbers.In this work,two-dimensional cobalt and nickel alloys@mesoporous carbon(CoNi@MC)composites were constructed via using CoNi layered double hydroxide@mesoporous polydopamine(CoNi LDH@MPDA)as sacrifice template.During the pyrolysis process,the MPDA is transformed into mesoporous carbon coated the surface of CoNi LDH that is further reduced to CoNi alloys.The mesoporous structure is conducive to the multi-reflection of electromagnetic waves and facilitates optimizing impedance matching.Heterogeneous interfaces between CoNi alloys and mesoporous carbon induce interface polarization.Multiple attenuation mechanism promotes the electromagnetic waves conversion.The maximum reflection loss of CoNi@MC composite is−70.86 dB and the widest effective absorption bandwidth is 7.74 GHz covering almost the entire Ku band.This strategy will be a guidance for designing electromagnetic absorbers.
基金the National Natural Science Foundation of China for their support under Grants No.62131002 and 62101057 and the National Key Research and Development Program of China(2021YFA0718800)The project was supported by the Fund of the State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)(IPOC2021ZT07),China.
文摘The manipulation of photons is a key technology for obtaining optical quantum information.In this study,we present a phase-modulated optomechanical system comprising two coupled cavity resonators and illustrate the phase-controlled photon blockade in the system.The coupling phase of the cavities reveals the interference of photons and introduces an unconventional photon-blockade effect.We also study the influence of the energy level fineness on the photon blockade and resonant frequency of the mechanical mode.Numerical simulations demonstrate that photon blockade can occur over a wide range of system parameters.These results have several implications for understanding the role of the state phase in quantum cavity optomechanics and provide a promising method for the realization of optomechanical quantum devices using photon blockade.
基金Supported by the Ministry of Education and Science of Ukraine under Grant No 0117U002253
文摘We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.
