Precise control and measurement of nanoparticles using low-power optical tweezers are pivotal for advancing single-particle analysis,nanoscale sensing,and energy transport research.In this work,we present the tipassis...Precise control and measurement of nanoparticles using low-power optical tweezers are pivotal for advancing single-particle analysis,nanoscale sensing,and energy transport research.In this work,we present the tipassisted nanoparticle capture system that simultaneously achieves localized temperature probing and nanoparticle trapping,significantly lowering the required laser power input.Unlike traditional metal-tip plasmonic techniques that predominantly rely on intense electric field gradients,our approach employs a silicon nanotip under resonant laser excitation,uniquely integrating optical forces,thermophoretic forces,and interatomic interactions for stable nanoparticle confinement.This synergistic collaboration mechanism enables approximately a 42%reduction in laser power density compared to conventional bowtie nanoaperture methods.This experimental method achieved direct and simultaneous Raman-based measurements of localized thermal dynamics,providing new insights into nanoscale thermodynamics during optical trapping.Additionally,the silicon nanotip demonstrates reduced thermal transport due to its confined nanoscale geometry,aligning closely with our theoretical predictions.Our integrated strategy of efficient nanoparticle manipulation coupled with precise thermal probing not only enhances overall energy efficiency but also broadens the scope of potential applications in cutting-edge nanoscience and nanotechnology.展开更多
The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source.Efficient fuel cycle to minimize strategic tritium inventory proves cru...The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source.Efficient fuel cycle to minimize strategic tritium inventory proves crucial for commercially viable fusion technologies.ZrCo alloy is considered as a promising candidate for fast isotope handling.However,cycling degradation caused by hydrogen-induced disproportionation results in severe tritium trapping,thus impeding its practical application.Herein,an isostructural transition is successfully constructed with low hysterisis,ameliorated plateau flatness of pressure-composition isotherms and improved high-temperature durability for hydrogen trapping minimization.Specifically,the optimal Zr_(0.7)Hf_(0.15)Nb_(0.15)Co_(0.6)Cu_(0.15)Ni_(0.25) alloy adopts Hf-Nb and Cu-Ni as Zr and Co side doping elements,exhibiting substantial thermodynamic destabilization with nearly 90℃ reduction of delivery temperature,and significant kinetic promotion with a threefold lower energy barrier.More importantly,both hydrogen utilization and cycling retention of optimal alloy are increased by about twenty times compared with pristine alloy after 100 cycles at 500℃.Minimized disproportionation driving force from both isostructural transition and suppressed 8e hydrogen occupation realizes full potential of optimal alloy.This work demonstrates the effectiveness of combining isostructural transformation and high-temperature durability improvement to enhance the hydrogen utilization of ZrCo-based alloys and other hydrogen storage materials.展开更多
Topological slow light and rainbow trapping tend to rely on large-scale interface structure in previous research work,which have restricted further miniaturization.In this work,we propose a method to realize slow ligh...Topological slow light and rainbow trapping tend to rely on large-scale interface structure in previous research work,which have restricted further miniaturization.In this work,we propose a method to realize slow light and rainbow trapping at the zigzag edge of a single valley photonic crystals(VPCs)bounded by air,which is very different from previous studies where rainbow trapping is supported at the interface separating two VPCs with inversion symmetry.By constructing the VPC–air boundaries and VPC–VPC interfaces experimentally,we have observed the topologically protected rainbow trapping simultaneously at the external and internal boundary.This work provides a feasible platform for the miniaturized optical communication devices such as optical buffers,optical storage and optical routing.展开更多
The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique re...The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constantdepth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic fields.Finally, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.展开更多
The four-color three-step selective photoionization process of atom is very important in laser isotope separation technology.The population trapping phenomena and their influences are studied theoretically in monochro...The four-color three-step selective photoionization process of atom is very important in laser isotope separation technology.The population trapping phenomena and their influences are studied theoretically in monochromatic and non-monochromatic laser fields based on the density matrix theory in this work.Time evolutions of the photoionization properties of the four-color,three-step process are given.The population trapping effects occur intensely in monochromatic excitation,while it gradually turns weak as the laser bandwidth increases.The effects of bandwidth,Rabi frequency,time delay,and frequency detuning on the population trapping effect are investigated in monochromatic and non-monochromatic laser fields.The effects of laser process parameters and atomic parameters on the effective selective photoionization are also discussed.The ionization probability and selectivity factors,as evaluation indexes,are difficult to improve synchronously by adjusting systematic parameters.Besides,the existence of metastable state may play a negative role when its population is low enough.展开更多
Charge trapping devices incorporating 2D materials and high-κdielectrics have emerged as promising candidates for compact,multifunctional memory devices compatible with silicon-based manufacturing processes.However,t...Charge trapping devices incorporating 2D materials and high-κdielectrics have emerged as promising candidates for compact,multifunctional memory devices compatible with silicon-based manufacturing processes.However,traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed.Here,we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al_(2)O_(3)trapping layer with a MoS_(2)channel,where charge traps reside within the Al_(2)O_(3)bulk confirmed by transfer curves with different gatevoltage sweeping rates and photoluminescence(PL)spectra.The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed(~300 ns),an extremely low OFF current of 10^(-14)A,a high ON/OFF current ratio of up to 10^(7),and stable retention and endurance properties.Furthermore,the device with a simple symmetrical structure exhibits VDpolarity-dependent reverse rectification behavior in the high resistance state(HRS),with a rectification ratio of 10^(5).Additionally,utilizing the synergistic modulation of the conductance of the MoS_(2)channel by V_(D)and V_(G),it achieves gate-tunable reverse rectifier and ternary logic capabilities.展开更多
Strengthened directivity with higher-order side lobes can be generated by the transducer with a larger radius at a higher frequency. The multi-annular pressure distributions are displayed in the cross-section of the a...Strengthened directivity with higher-order side lobes can be generated by the transducer with a larger radius at a higher frequency. The multi-annular pressure distributions are displayed in the cross-section of the acoustic vortices(AVs)which are formed by side lobes. In the near field, particles can be trapped in the valley region between the two annuli of the pressure peak, and cannot be moved to the vortex center. In this paper, a trapping method based on a sector transducer array is proposed, which is characterized by the continuously variable topological charge(CVTC). This acoustic field can not only enlarge the range of particle trapping but also improve the aggregation degree of the trapped particles. In the experiments, polyethylene particles with a diameter of 0.2 mm are trapped into the multi-annular valleys by the AV with a fixed topological charge. Nevertheless, by applying the CVTC, particles outside the radius of the AV can cross the pressure peak successfully and move to the vortex center. Theoretical studies are also verified by the experimental particles trapping using the AV with the continuous variation of three topological charges, and suggest the potential application of large-scale particle trapping in biomedical engineering.展开更多
We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pear...We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pearcey beams with different radii.Our theoretical exploration delves into various aspects,including the propagation dynamics,energy flux,orbital angular momentum,trapping force,and torque characteristics of TCPBs.The results reveal that the orbital angular momentum,trapping force,and torque of these beams can be finely tuned through the judicious manipulation of their topological charges(l_(1)and l_(2)).Notably,we observe a precise control mechanism wherein the force diminishes with|l_(1)+l_(2)|and|l_(1)-l_(2)|,while the torque exhibits enhancement by decreasing solely with|l_(1)+l_(2)|or increasing with|l_(1)-l_(2)|.These results not only provide quantitative insights into the optical trapping performance of TCPBs but also serve as a valuable reference for the ongoing development of innovative photonic tools.展开更多
We have experimentally achieved the all-optical trapping of a ^(40)Ca^(+)ion.An optical dipole trap was established using a high-power,far-detuned,tightly focused laser with a wavelength of 532 nm.The single ^(40)Ca^(...We have experimentally achieved the all-optical trapping of a ^(40)Ca^(+)ion.An optical dipole trap was established using a high-power,far-detuned,tightly focused laser with a wavelength of 532 nm.The single ^(40)Ca^(+)ion was trapped without any RF fields and demonstrated a long lifetime of over 3 s.In this experiment,we implemented several measures to improve the optical trapping probability,including focusing the dipole beam waist near the diffraction limit,precisely compensating for stray electric fields,and mitigating electron shelving in metastable states.The optical trapping of a ^(40)Ca^(+)ion eliminates the influence of micromotion induced by RF fields,potentially paving the way for development of all-optical trapping ion optical clocks.展开更多
Vertical GaN power MOSFET is a novel technology that offers great potential for power switching applications.Being still in an early development phase,vertical GaN devices are yet to be fully optimized and require car...Vertical GaN power MOSFET is a novel technology that offers great potential for power switching applications.Being still in an early development phase,vertical GaN devices are yet to be fully optimized and require careful studies to foster their development.In this work,we report on the physical insights into device performance improvements obtained during the development of vertical GaN-on-Si trench MOSFETs(TMOS’s)provided by TCAD simulations,enhancing the dependability of the adopted process optimization approaches.Specifically,two different TMOS devices are compared in terms of transfer-curve hysteresis(H)and subthreshold slope(SS),showing a≈75%H reduction along with a≈30%SS decrease.Simulations allow attributing the achieved improvements to a decrease in the border and interface traps,respectively.A sensitivity analysis is also carried out,allowing to quantify the additional trap density reduction required to minimize both figures of merit.展开更多
[Objective] To evaluate the control effect of yellow sticky cards and sex pheromone on Plutella xylostella and Liriomyza spp.,which can provide reference for large area extension of the technique.[Method] The integrat...[Objective] To evaluate the control effect of yellow sticky cards and sex pheromone on Plutella xylostella and Liriomyza spp.,which can provide reference for large area extension of the technique.[Method] The integrated assessment of trapping efficiency of colored sticky cards and sex pheromone on Liriomyza spp.and Plutella xylostella was conducted by field surveys and structured interview in Tonghai County,Yunnan Province,China.[Result] The results showed that yellow sticky cards and sex pheromone have strong power of trapping Liriomyza spp.and Plutella xylostella（3 414±720 and（219±157） head/piece,respectively）;the control cost by the usage of pesticide is the highest,（10 099.5±2 752.5） yuan/hm^2,yellow sticky cards and sex pheromone takes the second place,（1 125.0±465.0） yuan/hm^2,the control cost by the usage of yellow sticky cards is the lowest,（450.0 ±186.0）yuan/hm^2.Without the usage of yellow sticky cards and sex pheromone,pesticide application times and costs are（15.0±2.7） times and（12 070.5±2 136.0） yuan/hm^2;combined with usage of yellow sticky cards and sex pheromone,pesticide application times and costs reduce by 5.7 times and 4 618.5 yuan/hm^2.The ratio of trapped beneficial insects and target pests was 1 ∶1 131,which showed that the negative effect of yellow sticky cards and sex pheromone on the non-target insects was very limited.[Conclusion] The trapping approach has become popular among all the local farmers.Looking at the above factors,the trapping technology has strong application prospect and promotion value in pest control field.展开更多
Five different trapping treatments, spraying attractant on bottle surface and spraying attractant inside the bottles with 0, 50,100 and 200 mL water, were set to trap Bactrocera dorsalis and B. cucurbitae in guava （P...Five different trapping treatments, spraying attractant on bottle surface and spraying attractant inside the bottles with 0, 50,100 and 200 mL water, were set to trap Bactrocera dorsalis and B. cucurbitae in guava （Psidium guajava） park. The results showed that when the usage of attractant was 1 g, both Haonian and Wende had trapping effect on B. dorsalis and B. cucurbitae. The trapping effect of Haonian on B. dorsalis was better than that of Wende, while their trapping effects on B. cucurbitae was just the opposite. The trapping effects of different treatments had great difference. The trapping effect of Haonian on two species of fruit flies enhanced with the increasing volume of water, and reached the ma^mum value as the water volume was 200 mL. With the increasing volume of water, the trap- ping effect of Wende on two species of fruit flies first increased, and then decreased, which reached the maximum value as the water volume was 50 mL. Different treatments with attractants spraying inside bottles had better trapping effects on two species of fruit flies than that spraying on bottle surface.展开更多
A 2D electron-longitudinal-acoustic-phonon interaction Hamiltonian is derived and used to calculate the groundstate energy of the acoustic polarons in two dimensions. The numerical results for the ground-state energy ...A 2D electron-longitudinal-acoustic-phonon interaction Hamiltonian is derived and used to calculate the groundstate energy of the acoustic polarons in two dimensions. The numerical results for the ground-state energy of the acoustic polarons in two and three dimensions are obtained. The 3D results agree with those obtained by using the Feynman path-integral approach. It is found that the critical coupling constant of the transition from the quasifree state to the self-trapped state in the 2D case is much smaller than in the 3D case for a given cutoff wave-vector. The theory has been used to judge the possibility of the self-trapping for several real materials. The results indicate that the self-trappings of the electrons in AlN and the holes in AlN and GaN are expected to be observed in 2D systems.展开更多
The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the pr...The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the precipitate particles newly formed in the weld metal by the addition of Ce and Y to a certain alloy system was characterized. Moreover,the hydrogen trapping efficiency expressed as the reduction of the diffusible hydrogen in the weld metal was analyzed. The results showed that the addition of Ce and/or Y to this alloy system led to the formation of a mixed type of(Ce,Ti)-based oxide,(Y,Ni)-based carbide,or(Ce,Y,Ti)-based oxide particles. Because of the high activation energy of the mixed type of particles(≥ 150 k J/mol),the trapping efficiency for hydrogen was considered to be sufficiently high to effectively reduce the diffusible hydrogen content.展开更多
We propose a simple and efficient method that uses a single focused hybrid vector beam to confine metallic Rayleigh particles at multiple positions.We study the force mechanisms of multiple trapping by analyzing the g...We propose a simple and efficient method that uses a single focused hybrid vector beam to confine metallic Rayleigh particles at multiple positions.We study the force mechanisms of multiple trapping by analyzing the gradient and scattering forces.It is observed that the wavelength and topological charges of the hybrid vector beam regulate the trapping positions and number of optical trap sites.The proposed method can be implemented easily in three-dimensional space, and it facilitates both trapping and organization of particles.Thus, it can provide an effective and controllable means for nanoparticle manipulation.展开更多
Research on chip-scale atomic clocks （CSACs） based on coherent population trapping （CPT） is reviewed. The back- ground and the inspiration for the research are described, including the important schemes proposed t...Research on chip-scale atomic clocks （CSACs） based on coherent population trapping （CPT） is reviewed. The back- ground and the inspiration for the research are described, including the important schemes proposed to improve the CPT signal quality, the selection of atoms and buffer gases, and the development of micro-cell fabrication. With regard to the re- liability, stability, and service life of the CSACs, the research regarding the sensitivity of the CPT resonance to temperature and laser power changes is also reviewed, as well as the CPT resonance＇s collision and light of frequency shifts. The first generation CSACs have already been developed but its characters are still far from our expectations. Our conclusion is that miniaturization and power reduction are the most important aspects calling for further research.展开更多
Optical tweezers have been a valuable research tool since their invention in the 1980s. One of the most important developments in optical tweezers in recent years is the creation of two-dimensional arrays of optical t...Optical tweezers have been a valuable research tool since their invention in the 1980s. One of the most important developments in optical tweezers in recent years is the creation of two-dimensional arrays of optical traps. In this paper, a method based on interference is discussed to form gradient laser fields, which may cause the spatial modulation of particle concentration. The parameters related to the optical tweezers array are discussed in detail and simulated by the Matlab software to show the influence of important parameters on the distribution of particle concentration. The spatial redistribution of particles in a laser interference field can also be predicted according to the theoretical analysis.展开更多
Superlattice photonic crystals (SPhCs) possess considerablepotentials as building blocks for constructing high-performancedevices because of their great flexibilities in opticalmanipulation. From the prospective of pr...Superlattice photonic crystals (SPhCs) possess considerablepotentials as building blocks for constructing high-performancedevices because of their great flexibilities in opticalmanipulation. From the prospective of practical applications,scalable fabrication of SPhCs with large-area uniformity and precisegeometrical controllability has been considered as one prerequisitebut still remains a challenge.展开更多
Beam dams are a highly effective and commonly used open-type check dam in debris-flow hazard mitigation. In this study, dimensional analysis was used to obtain empirical equations for quantitatively determining the se...Beam dams are a highly effective and commonly used open-type check dam in debris-flow hazard mitigation. In this study, dimensional analysis was used to obtain empirical equations for quantitatively determining the sediment-trapping and flow-regulating characteristics of a beam dam. To determine the coefficients of the empirical equations, flume experiments were conducted to simulate the trapping and regulating processes. The flow pattern, trapping, and regulating characteristics were investigated when debris flows passed through a beam dam. Debris-flow bulk density and peak discharge, and sediment-trapping ratios, were measured directly and indirectly. The results showed that three blocking actions occurred, and that blockage-breaking considerably influenced the trapping and regulating performance of the beam dam. The relative opening size and the sediment concentration were the two main factors affecting the performance of the beam dam. The ratio of trapping sediment decreased with relative opening, and increased with sediment concentration as well as reducing ratio of bulk density and reducing ratio of peak discharge. The sediment concentration and relative opening were the leading factors influencing the trapping and regulating sediment of a beam dam, followed by flume gradient. The results showed that the calculated values obtained using empirical equations were in good agreement with the values derived from the experiments, and that the deviation was acceptable. Finally, taking Zechawa Gully as an example, using the empirical equations we designed the opening size of a beam dam aimed to trap sediment and regulate peak discharge of debris flow in the main gully.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52206107)the National Key R&D Program of China(Grant No.2023YFE0120200)。
文摘Precise control and measurement of nanoparticles using low-power optical tweezers are pivotal for advancing single-particle analysis,nanoscale sensing,and energy transport research.In this work,we present the tipassisted nanoparticle capture system that simultaneously achieves localized temperature probing and nanoparticle trapping,significantly lowering the required laser power input.Unlike traditional metal-tip plasmonic techniques that predominantly rely on intense electric field gradients,our approach employs a silicon nanotip under resonant laser excitation,uniquely integrating optical forces,thermophoretic forces,and interatomic interactions for stable nanoparticle confinement.This synergistic collaboration mechanism enables approximately a 42%reduction in laser power density compared to conventional bowtie nanoaperture methods.This experimental method achieved direct and simultaneous Raman-based measurements of localized thermal dynamics,providing new insights into nanoscale thermodynamics during optical trapping.Additionally,the silicon nanotip demonstrates reduced thermal transport due to its confined nanoscale geometry,aligning closely with our theoretical predictions.Our integrated strategy of efficient nanoparticle manipulation coupled with precise thermal probing not only enhances overall energy efficiency but also broadens the scope of potential applications in cutting-edge nanoscience and nanotechnology.
基金supports from the National Key Research and Development Program of China(2022YFE03170002)the National Natural Science Foundation of China(52071286 and U2030208).
文摘The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source.Efficient fuel cycle to minimize strategic tritium inventory proves crucial for commercially viable fusion technologies.ZrCo alloy is considered as a promising candidate for fast isotope handling.However,cycling degradation caused by hydrogen-induced disproportionation results in severe tritium trapping,thus impeding its practical application.Herein,an isostructural transition is successfully constructed with low hysterisis,ameliorated plateau flatness of pressure-composition isotherms and improved high-temperature durability for hydrogen trapping minimization.Specifically,the optimal Zr_(0.7)Hf_(0.15)Nb_(0.15)Co_(0.6)Cu_(0.15)Ni_(0.25) alloy adopts Hf-Nb and Cu-Ni as Zr and Co side doping elements,exhibiting substantial thermodynamic destabilization with nearly 90℃ reduction of delivery temperature,and significant kinetic promotion with a threefold lower energy barrier.More importantly,both hydrogen utilization and cycling retention of optimal alloy are increased by about twenty times compared with pristine alloy after 100 cycles at 500℃.Minimized disproportionation driving force from both isostructural transition and suppressed 8e hydrogen occupation realizes full potential of optimal alloy.This work demonstrates the effectiveness of combining isostructural transformation and high-temperature durability improvement to enhance the hydrogen utilization of ZrCo-based alloys and other hydrogen storage materials.
基金Project supported by the National Natural Science Foundation of China(Grant No.12374302)the Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQMSX0872).
文摘Topological slow light and rainbow trapping tend to rely on large-scale interface structure in previous research work,which have restricted further miniaturization.In this work,we propose a method to realize slow light and rainbow trapping at the zigzag edge of a single valley photonic crystals(VPCs)bounded by air,which is very different from previous studies where rainbow trapping is supported at the interface separating two VPCs with inversion symmetry.By constructing the VPC–air boundaries and VPC–VPC interfaces experimentally,we have observed the topologically protected rainbow trapping simultaneously at the external and internal boundary.This work provides a feasible platform for the miniaturized optical communication devices such as optical buffers,optical storage and optical routing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12104414,12122412,12104464,and 12104413)the China Postdoctoral Science Foundation(Grant No.2021M702955).
文摘The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constantdepth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic fields.Finally, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.
文摘The four-color three-step selective photoionization process of atom is very important in laser isotope separation technology.The population trapping phenomena and their influences are studied theoretically in monochromatic and non-monochromatic laser fields based on the density matrix theory in this work.Time evolutions of the photoionization properties of the four-color,three-step process are given.The population trapping effects occur intensely in monochromatic excitation,while it gradually turns weak as the laser bandwidth increases.The effects of bandwidth,Rabi frequency,time delay,and frequency detuning on the population trapping effect are investigated in monochromatic and non-monochromatic laser fields.The effects of laser process parameters and atomic parameters on the effective selective photoionization are also discussed.The ionization probability and selectivity factors,as evaluation indexes,are difficult to improve synchronously by adjusting systematic parameters.Besides,the existence of metastable state may play a negative role when its population is low enough.
基金supported by the National Key Research&Development Project of China(Grant No.2022YFA1204100)the National Natural Science Foundation of China(Grant No.62488201)+1 种基金CAS Project for Young Scientists in Basic Research(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘Charge trapping devices incorporating 2D materials and high-κdielectrics have emerged as promising candidates for compact,multifunctional memory devices compatible with silicon-based manufacturing processes.However,traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed.Here,we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al_(2)O_(3)trapping layer with a MoS_(2)channel,where charge traps reside within the Al_(2)O_(3)bulk confirmed by transfer curves with different gatevoltage sweeping rates and photoluminescence(PL)spectra.The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed(~300 ns),an extremely low OFF current of 10^(-14)A,a high ON/OFF current ratio of up to 10^(7),and stable retention and endurance properties.Furthermore,the device with a simple symmetrical structure exhibits VDpolarity-dependent reverse rectification behavior in the high resistance state(HRS),with a rectification ratio of 10^(5).Additionally,utilizing the synergistic modulation of the conductance of the MoS_(2)channel by V_(D)and V_(G),it achieves gate-tunable reverse rectifier and ternary logic capabilities.
基金Project supported by the National Key R&D Program of China(Grant No.2023YFE0201900)。
文摘Strengthened directivity with higher-order side lobes can be generated by the transducer with a larger radius at a higher frequency. The multi-annular pressure distributions are displayed in the cross-section of the acoustic vortices(AVs)which are formed by side lobes. In the near field, particles can be trapped in the valley region between the two annuli of the pressure peak, and cannot be moved to the vortex center. In this paper, a trapping method based on a sector transducer array is proposed, which is characterized by the continuously variable topological charge(CVTC). This acoustic field can not only enlarge the range of particle trapping but also improve the aggregation degree of the trapped particles. In the experiments, polyethylene particles with a diameter of 0.2 mm are trapped into the multi-annular valleys by the AV with a fixed topological charge. Nevertheless, by applying the CVTC, particles outside the radius of the AV can cross the pressure peak successfully and move to the vortex center. Theoretical studies are also verified by the experimental particles trapping using the AV with the continuous variation of three topological charges, and suggest the potential application of large-scale particle trapping in biomedical engineering.
基金Project supported by the National Natural Science Foundation of China(Grant No.11604058)the Guangxi Natural Science Foundation(Grant Nos.2020GXNSFAA297041 and 2023JJA110112)the Innovation Project of Guangxi Graduate Education(Grant No.YCSW2023083)。
文摘We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pearcey beams with different radii.Our theoretical exploration delves into various aspects,including the propagation dynamics,energy flux,orbital angular momentum,trapping force,and torque characteristics of TCPBs.The results reveal that the orbital angular momentum,trapping force,and torque of these beams can be finely tuned through the judicious manipulation of their topological charges(l_(1)and l_(2)).Notably,we observe a precise control mechanism wherein the force diminishes with|l_(1)+l_(2)|and|l_(1)-l_(2)|,while the torque exhibits enhancement by decreasing solely with|l_(1)+l_(2)|or increasing with|l_(1)-l_(2)|.These results not only provide quantitative insights into the optical trapping performance of TCPBs but also serve as a valuable reference for the ongoing development of innovative photonic tools.
基金supported by the National Basic Research R&D Program of China(Grant Nos.2022YFB3904001 and 2018YFA0307500)the National Natural Science Foundation of China(Grant Nos.12022414 and 11934014)+1 种基金the Natural Science Foundation of Hubei Province(Grant No.2022CFA013)the CAS Project for Young Scientists in Basic Research(Grant Nos.YSBR-085 and YSBR-055)。
文摘We have experimentally achieved the all-optical trapping of a ^(40)Ca^(+)ion.An optical dipole trap was established using a high-power,far-detuned,tightly focused laser with a wavelength of 532 nm.The single ^(40)Ca^(+)ion was trapped without any RF fields and demonstrated a long lifetime of over 3 s.In this experiment,we implemented several measures to improve the optical trapping probability,including focusing the dipole beam waist near the diffraction limit,precisely compensating for stray electric fields,and mitigating electron shelving in metastable states.The optical trapping of a ^(40)Ca^(+)ion eliminates the influence of micromotion induced by RF fields,potentially paving the way for development of all-optical trapping ion optical clocks.
基金funding from the Electronic Component Systems for European Leadership Joint Undertaking (ECSEL JU),under grant agreement No.101007229support from the European Union’s Horizon 2020 Research and Innovation Programme,Germany,France,Belgium,Austria,Sweden,Spain,and Italy
文摘Vertical GaN power MOSFET is a novel technology that offers great potential for power switching applications.Being still in an early development phase,vertical GaN devices are yet to be fully optimized and require careful studies to foster their development.In this work,we report on the physical insights into device performance improvements obtained during the development of vertical GaN-on-Si trench MOSFETs(TMOS’s)provided by TCAD simulations,enhancing the dependability of the adopted process optimization approaches.Specifically,two different TMOS devices are compared in terms of transfer-curve hysteresis(H)and subthreshold slope(SS),showing a≈75%H reduction along with a≈30%SS decrease.Simulations allow attributing the achieved improvements to a decrease in the border and interface traps,respectively.A sensitivity analysis is also carried out,allowing to quantify the additional trap density reduction required to minimize both figures of merit.
基金Supported by Development Program of Misereor Foundation of Germany(335-0311028Z)~~
文摘[Objective] To evaluate the control effect of yellow sticky cards and sex pheromone on Plutella xylostella and Liriomyza spp.,which can provide reference for large area extension of the technique.[Method] The integrated assessment of trapping efficiency of colored sticky cards and sex pheromone on Liriomyza spp.and Plutella xylostella was conducted by field surveys and structured interview in Tonghai County,Yunnan Province,China.[Result] The results showed that yellow sticky cards and sex pheromone have strong power of trapping Liriomyza spp.and Plutella xylostella（3 414±720 and（219±157） head/piece,respectively）;the control cost by the usage of pesticide is the highest,（10 099.5±2 752.5） yuan/hm^2,yellow sticky cards and sex pheromone takes the second place,（1 125.0±465.0） yuan/hm^2,the control cost by the usage of yellow sticky cards is the lowest,（450.0 ±186.0）yuan/hm^2.Without the usage of yellow sticky cards and sex pheromone,pesticide application times and costs are（15.0±2.7） times and（12 070.5±2 136.0） yuan/hm^2;combined with usage of yellow sticky cards and sex pheromone,pesticide application times and costs reduce by 5.7 times and 4 618.5 yuan/hm^2.The ratio of trapped beneficial insects and target pests was 1 ∶1 131,which showed that the negative effect of yellow sticky cards and sex pheromone on the non-target insects was very limited.[Conclusion] The trapping approach has become popular among all the local farmers.Looking at the above factors,the trapping technology has strong application prospect and promotion value in pest control field.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest( 201103026-1)
文摘Five different trapping treatments, spraying attractant on bottle surface and spraying attractant inside the bottles with 0, 50,100 and 200 mL water, were set to trap Bactrocera dorsalis and B. cucurbitae in guava （Psidium guajava） park. The results showed that when the usage of attractant was 1 g, both Haonian and Wende had trapping effect on B. dorsalis and B. cucurbitae. The trapping effect of Haonian on B. dorsalis was better than that of Wende, while their trapping effects on B. cucurbitae was just the opposite. The trapping effects of different treatments had great difference. The trapping effect of Haonian on two species of fruit flies enhanced with the increasing volume of water, and reached the ma^mum value as the water volume was 200 mL. With the increasing volume of water, the trap- ping effect of Wende on two species of fruit flies first increased, and then decreased, which reached the maximum value as the water volume was 50 mL. Different treatments with attractants spraying inside bottles had better trapping effects on two species of fruit flies than that spraying on bottle surface.
基金Project supported by the Doctoral Program Foundation of Institutions of Higher Education China （Grant No 20040126003） and the Natural Science Foundation of Inner Mongol of China （Grant No 200408020101）.
文摘A 2D electron-longitudinal-acoustic-phonon interaction Hamiltonian is derived and used to calculate the groundstate energy of the acoustic polarons in two dimensions. The numerical results for the ground-state energy of the acoustic polarons in two and three dimensions are obtained. The 3D results agree with those obtained by using the Feynman path-integral approach. It is found that the critical coupling constant of the transition from the quasifree state to the self-trapped state in the 2D case is much smaller than in the 3D case for a given cutoff wave-vector. The theory has been used to judge the possibility of the self-trapping for several real materials. The results indicate that the self-trappings of the electrons in AlN and the holes in AlN and GaN are expected to be observed in 2D systems.
文摘The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the precipitate particles newly formed in the weld metal by the addition of Ce and Y to a certain alloy system was characterized. Moreover,the hydrogen trapping efficiency expressed as the reduction of the diffusible hydrogen in the weld metal was analyzed. The results showed that the addition of Ce and/or Y to this alloy system led to the formation of a mixed type of(Ce,Ti)-based oxide,(Y,Ni)-based carbide,or(Ce,Y,Ti)-based oxide particles. Because of the high activation energy of the mixed type of particles(≥ 150 k J/mol),the trapping efficiency for hydrogen was considered to be sufficiently high to effectively reduce the diffusible hydrogen content.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604050,91636109,61575041,and 61875242)the Fundamental Research Funds for the Central Universities at Xiamen University,China(Grant No.20720190057)+3 种基金the Natural Science Foundation of Fujian Province of China for Distinguished Young Scientists(Grant No.2015J06002)the Program for New Century Excellent Talents in University of China(Grant No.NCET-13-0495)the Science and Technology Planning Project of Guangdong Province,China(Grant No.2016B010113004)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2015A030310296 and 2018A030313347)
文摘We propose a simple and efficient method that uses a single focused hybrid vector beam to confine metallic Rayleigh particles at multiple positions.We study the force mechanisms of multiple trapping by analyzing the gradient and scattering forces.It is observed that the wavelength and topological charges of the hybrid vector beam regulate the trapping positions and number of optical trap sites.The proposed method can be implemented easily in three-dimensional space, and it facilitates both trapping and organization of particles.Thus, it can provide an effective and controllable means for nanoparticle manipulation.
基金Project support by the National Natural Science Foundation of China(Grant No.11074012)
文摘Research on chip-scale atomic clocks （CSACs） based on coherent population trapping （CPT） is reviewed. The back- ground and the inspiration for the research are described, including the important schemes proposed to improve the CPT signal quality, the selection of atoms and buffer gases, and the development of micro-cell fabrication. With regard to the re- liability, stability, and service life of the CSACs, the research regarding the sensitivity of the CPT resonance to temperature and laser power changes is also reviewed, as well as the CPT resonance＇s collision and light of frequency shifts. The first generation CSACs have already been developed but its characters are still far from our expectations. Our conclusion is that miniaturization and power reduction are the most important aspects calling for further research.
基金Project supported by the National Natural Science Foundation of China (Grant No 20505002)the Excellent Young Scholars Research Fund of Beijing Institute of Technology (Grant No 000Y06-23)the Excellent Scholars Research Fund of Beijing(Grant No 20071D1600300394)
文摘Optical tweezers have been a valuable research tool since their invention in the 1980s. One of the most important developments in optical tweezers in recent years is the creation of two-dimensional arrays of optical traps. In this paper, a method based on interference is discussed to form gradient laser fields, which may cause the spatial modulation of particle concentration. The parameters related to the optical tweezers array are discussed in detail and simulated by the Matlab software to show the influence of important parameters on the distribution of particle concentration. The spatial redistribution of particles in a laser interference field can also be predicted according to the theoretical analysis.
文摘Superlattice photonic crystals (SPhCs) possess considerablepotentials as building blocks for constructing high-performancedevices because of their great flexibilities in opticalmanipulation. From the prospective of practical applications,scalable fabrication of SPhCs with large-area uniformity and precisegeometrical controllability has been considered as one prerequisitebut still remains a challenge.
基金supported by the Chinese Academy of Sciences and Organization Department of Sichuan Provincial Party Committee“Light of West China”Program(the key control techniques of glacial debris flow along the Sichuan-Tibet Railway)the National Natural Science Foundation of China(Grant No.41772343)STS Project of the Chinese Academy of Sciences(KFJ-STS-ZDTP015)
文摘Beam dams are a highly effective and commonly used open-type check dam in debris-flow hazard mitigation. In this study, dimensional analysis was used to obtain empirical equations for quantitatively determining the sediment-trapping and flow-regulating characteristics of a beam dam. To determine the coefficients of the empirical equations, flume experiments were conducted to simulate the trapping and regulating processes. The flow pattern, trapping, and regulating characteristics were investigated when debris flows passed through a beam dam. Debris-flow bulk density and peak discharge, and sediment-trapping ratios, were measured directly and indirectly. The results showed that three blocking actions occurred, and that blockage-breaking considerably influenced the trapping and regulating performance of the beam dam. The relative opening size and the sediment concentration were the two main factors affecting the performance of the beam dam. The ratio of trapping sediment decreased with relative opening, and increased with sediment concentration as well as reducing ratio of bulk density and reducing ratio of peak discharge. The sediment concentration and relative opening were the leading factors influencing the trapping and regulating sediment of a beam dam, followed by flume gradient. The results showed that the calculated values obtained using empirical equations were in good agreement with the values derived from the experiments, and that the deviation was acceptable. Finally, taking Zechawa Gully as an example, using the empirical equations we designed the opening size of a beam dam aimed to trap sediment and regulate peak discharge of debris flow in the main gully.
