Quantum defects in solid materials,such as nitrogen-vacancy color centers in diamond,have been extensively studied and successfully demonstrated as single photon emitters and potential qubits for quantum computers.How...Quantum defects in solid materials,such as nitrogen-vacancy color centers in diamond,have been extensively studied and successfully demonstrated as single photon emitters and potential qubits for quantum computers.However,a major challenge has always been positioning these quantum defects near the sample surface for mea-suring or sensing purposes.The emergence of quantum defects in two-dimensional(2D)van der Waals(vdW)materials open up new opportunities for overcoming these limitations.These materials possess unique properties,including vdW interlayer coupling and clean surfaces without unsaturated dangling bonds,which provide greater advantages for manufacturing multi-qubit systems.In this review,we present the research progress on quantum defects in 2D vdW materials,covering quantum guidelines for spin defects in solid state,the latest demonstra-tions of quantum defects,the unique methods and techniques for generating and modulating defects in 2D vdW materials.展开更多
In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode （LD）, we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by met...In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode （LD）, we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by metal organic chemical vapor deposition （MOCVD）. For the devices with 100-ttm-wide stripe and 1000-/zm-long cavity under continuous-wave （CW） operation condition, the typical threshold current is 190 mA, the slope efficiency is 1.31 W/A, the wall-plug efficiency reaches 63%, and the maximum output power reaches higher than 7 W. And the internal absorption value decreases to 1.5 cm^-1.展开更多
The dynamic tunability of vector beams(VBs)with metasurfaces plays an important role in the discovery of exotic optical phenomena and development of classic and quantum applications.Using the tunability with longitudi...The dynamic tunability of vector beams(VBs)with metasurfaces plays an important role in the discovery of exotic optical phenomena and development of classic and quantum applications.Using the tunability with longitudinal propagation distance and multifunctional capability of the quarter-waveplate(QWP)meta-atoms,dielectric metasurfaces were designed to generate high-order Poincaré(HOP)beams with tunable elliptical polarization states at arbitrary latitudes.The metasurface contained two interleaved sub-metasurfaces of QWP meta-atoms,each configured with helical,hyperbolic,and primary and secondary axicon-phase profiles to generate a vortex,beam focus,and beam deflection,respectively.Importantly,the axicons were suitably designed by combining the propagation and geometric phases to introduce differences in the z-component wavevectors,and the amplitudes of the co-and cross-polarized vortices were tuned by the longitudinal distance.The method broke through the limitation of previously generating only the linear polarization states on the equator of the HOP sphere,and it also circumvented the traditional tunability using the troublesome waveplate-polarizer combination.This study is of great significance for the miniaturization and integration of optical systems for applications such as optical communications,micromanipulation,and high-precision detection.展开更多
This study utilises linear-scaling density functional theory(DFT)and develops a new machine-learning potential for carbon and nitrogen(GAP-CN),based on the carbon potential(GAP20),to investigate the interaction betwee...This study utilises linear-scaling density functional theory(DFT)and develops a new machine-learning potential for carbon and nitrogen(GAP-CN),based on the carbon potential(GAP20),to investigate the interaction between carbon self-interstitials and nitrogen-vacancy(NV)centres in diamond,focusing on their excited states and diffusion behaviour.From the simulated excited states,‘Bright’,‘Spike’,and‘Dark’defect configurations are classified based on their absorption spectrum features.Furthermore,machine learning molecular dynamics simulation provides insight into the possible diffusion mechanism of Ci and NV,showing that Ci can diffuse away or recombine with NV.The study yields new insight into the formation of NV defects in diamond for quantum technology applications.展开更多
基金supported by the National Natural Science Founda-tion of China(92265110,62174179,61888102 and 62204259)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB33000000 and XDB28000000)the Key Research Program of Frontier Sciences of CAS(QYZDJ-SSWSLH042 and XDPB22).
文摘Quantum defects in solid materials,such as nitrogen-vacancy color centers in diamond,have been extensively studied and successfully demonstrated as single photon emitters and potential qubits for quantum computers.However,a major challenge has always been positioning these quantum defects near the sample surface for mea-suring or sensing purposes.The emergence of quantum defects in two-dimensional(2D)van der Waals(vdW)materials open up new opportunities for overcoming these limitations.These materials possess unique properties,including vdW interlayer coupling and clean surfaces without unsaturated dangling bonds,which provide greater advantages for manufacturing multi-qubit systems.In this review,we present the research progress on quantum defects in 2D vdW materials,covering quantum guidelines for spin defects in solid state,the latest demonstra-tions of quantum defects,the unique methods and techniques for generating and modulating defects in 2D vdW materials.
基金supported by the National Natural Science Foundation of China (No.50472068)the Program for New Century Excellent Talents in University
文摘In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode （LD）, we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by metal organic chemical vapor deposition （MOCVD）. For the devices with 100-ttm-wide stripe and 1000-/zm-long cavity under continuous-wave （CW） operation condition, the typical threshold current is 190 mA, the slope efficiency is 1.31 W/A, the wall-plug efficiency reaches 63%, and the maximum output power reaches higher than 7 W. And the internal absorption value decreases to 1.5 cm^-1.
基金National Natural Science Foundation of China(62175134,62375159,12174226,12274478)Natural Science Foundation of Shandong Province(ZR2022MF248)。
文摘The dynamic tunability of vector beams(VBs)with metasurfaces plays an important role in the discovery of exotic optical phenomena and development of classic and quantum applications.Using the tunability with longitudinal propagation distance and multifunctional capability of the quarter-waveplate(QWP)meta-atoms,dielectric metasurfaces were designed to generate high-order Poincaré(HOP)beams with tunable elliptical polarization states at arbitrary latitudes.The metasurface contained two interleaved sub-metasurfaces of QWP meta-atoms,each configured with helical,hyperbolic,and primary and secondary axicon-phase profiles to generate a vortex,beam focus,and beam deflection,respectively.Importantly,the axicons were suitably designed by combining the propagation and geometric phases to introduce differences in the z-component wavevectors,and the amplitudes of the co-and cross-polarized vortices were tuned by the longitudinal distance.The method broke through the limitation of previously generating only the linear polarization states on the equator of the HOP sphere,and it also circumvented the traditional tunability using the troublesome waveplate-polarizer combination.This study is of great significance for the miniaturization and integration of optical systems for applications such as optical communications,micromanipulation,and high-precision detection.
基金the use of the University of Oxford Advanced Research Computing(ARC)facility in carrying out this work(https://doi.org/10.5281/zenodo.22558).Additionally,we acknowledge the use of NQIT computing nodes and the Quantum Computing and Simulation Hub.J.C.A.P.acknowledges the support of St.Edmund Hall,University of Oxford,through the Cooksey Early Career Teaching and Research Fellowship,and the embedded CSE programme of the ARCHER UK National Supercomputing Service.We extend our thanks to Yuxing Zhou for valuable suggestions on ML potential training,to Xingrui Cheng for providing experimental data,and to Jacx Chan for offering meaningful insights for this work.
文摘This study utilises linear-scaling density functional theory(DFT)and develops a new machine-learning potential for carbon and nitrogen(GAP-CN),based on the carbon potential(GAP20),to investigate the interaction between carbon self-interstitials and nitrogen-vacancy(NV)centres in diamond,focusing on their excited states and diffusion behaviour.From the simulated excited states,‘Bright’,‘Spike’,and‘Dark’defect configurations are classified based on their absorption spectrum features.Furthermore,machine learning molecular dynamics simulation provides insight into the possible diffusion mechanism of Ci and NV,showing that Ci can diffuse away or recombine with NV.The study yields new insight into the formation of NV defects in diamond for quantum technology applications.
