Non-carrier-injection light-emitting diodes (NCI-LEDs) are expected to be widely used in next generation micro-display technologies, including Micro-LEDs and nano-pixel light-emitting displays due to their simple device structure. However, because there is no charge carrier injection from external electrodes, carrier transport behavior of the NCI-LED cannot be described by using the traditional PN junction and LED theory. Therefore, establishing a carrier-transport model for the NCI-LED is of great significance for understanding its working mechanism and for improving device performance. In this paper, carrier transport mathematical model of the NCI-LED is established and the mechanical behavior of charge-carrier transport is analyzed quantitatively. Based on the mathematical model, the working mechanism of the NCI-LED is explained, the carrier transport characteristics of the device are obtained. Additionally, the key features, including the length of the induced charge region, the forward biased voltage across the internal PN junction, and the reverse biased voltage across the internal PN junction are studied. Their relationships with the applied frequency of the applied driving voltage are revealed. It is found that both the forward and reverse biases of the internal PN junction increase with the driving frequency. When the driving frequency reaches a certain value, the forward and reverse bias of the PN junction would be maintained at a maximum value. Moreover, the length of the induced charge region decreases with the increase of the driving frequency, and when the frequency reaches a certain value, the induced charge region would always be in the state of exhaustion. According to the mathematical model, suggestions for the device optimization design are provided: (1) Reducing the doping concentration of the induced charge regions can effectively increase the voltage drop across the internal LED; (2) Employing the tunneling effect occurring in the reverse-biased PN junction can effectively improve the electroluminescence intensity; (3) Using square-wave driving voltage can obtain a larger voltage drop across the internal LED and increase the electroluminescence intensity. This work on the carrier transport model is expected to provide a clear physical image for understanding the working mechanism of NCI-LED, and to provide a theoretical guidance for optimizing the device structure.
{"title":"Carrier Transport Model of Non-carrier-injection LED","authors":"Zhao Jian-Cheng, Wu Chao-Xing, Guo Tai-Liang","doi":"10.7498/aps.72.20221831","DOIUrl":"https://doi.org/10.7498/aps.72.20221831","url":null,"abstract":"Non-carrier-injection light-emitting diodes (NCI-LEDs) are expected to be widely used in next generation micro-display technologies, including Micro-LEDs and nano-pixel light-emitting displays due to their simple device structure. However, because there is no charge carrier injection from external electrodes, carrier transport behavior of the NCI-LED cannot be described by using the traditional PN junction and LED theory. Therefore, establishing a carrier-transport model for the NCI-LED is of great significance for understanding its working mechanism and for improving device performance. In this paper, carrier transport mathematical model of the NCI-LED is established and the mechanical behavior of charge-carrier transport is analyzed quantitatively. Based on the mathematical model, the working mechanism of the NCI-LED is explained, the carrier transport characteristics of the device are obtained. Additionally, the key features, including the length of the induced charge region, the forward biased voltage across the internal PN junction, and the reverse biased voltage across the internal PN junction are studied. Their relationships with the applied frequency of the applied driving voltage are revealed. It is found that both the forward and reverse biases of the internal PN junction increase with the driving frequency. When the driving frequency reaches a certain value, the forward and reverse bias of the PN junction would be maintained at a maximum value. Moreover, the length of the induced charge region decreases with the increase of the driving frequency, and when the frequency reaches a certain value, the induced charge region would always be in the state of exhaustion. According to the mathematical model, suggestions for the device optimization design are provided: (1) Reducing the doping concentration of the induced charge regions can effectively increase the voltage drop across the internal LED; (2) Employing the tunneling effect occurring in the reverse-biased PN junction can effectively improve the electroluminescence intensity; (3) Using square-wave driving voltage can obtain a larger voltage drop across the internal LED and increase the electroluminescence intensity. This work on the carrier transport model is expected to provide a clear physical image for understanding the working mechanism of NCI-LED, and to provide a theoretical guidance for optimizing the device structure.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74763898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wang Yue, Wang Lun, Sun Baixun, Lang Peng, Xu Yang, Zhao Zhenlong, Song Xiaowei, Ji Boyu, Lin Jingquan
Localized Surface Plasmon (LSP) in nanostructure excited by Surface Plasmon Polariton (SPP) corresponds to stronger near-field enhancement and special spectral and dynamic responses that provides a new path to explore the interaction between light and matter. Meanwhile, this scheme can also release the signal background noise and structural thermal effect, and improve the performance of plasmonic components and sensing detectors based on LSP. However, the current research on this aspect is still insufficient. In this paper, we investigated the near-field characteristics of a plasmon composite structure composed of plasmon focusing lens and gold nanorod under the excitation of dual-beam using Finite-Difference Time-Domain (FDTD) method. The result shows that the near-field intensity control on the upper surface and in the gap position of the nanorod can be achieved by adjusting the relative time delay between the first light beam (used to excite SPP) and the second light beam (used to excite LSP). Specifically, the maximum adjustment range of the near-field intensity corresponding to 770 nm resonant mode in the gap position is about 23, and the adjustment period is about 2.4 fs. In a resonant mode dominated by SPP at a wavelength of 999 nm, the near-field intensity adjustment range is as small as 6, and the adjustment period is about 4 fs. On the upper surface of the structure, the adjustment range of the near-field intensity of the two resonant modes (719 nm and 802 nm) is basically the same (about 15), and the adjustment period is 2.4 fs and 2.8 fs. The achievement of the near field control is attributed to the coherent superposition of SPP-excited LSP with light-excited LSP. In addition, the dephasing time of the coupling field was investigated using quasi- normal mode. It is found that the nanorod structure will correspond to different dephasing time under different relative time delay between two excitation light beams. Specifically, for the time delay of 0.72 fs (Δt=0.72 fs), the corresponding dephasing time for both modes is the same of 6.0 fs. For Δt=1.92 fs, the dephasing time of the longer-wavelength mode is 7.1 fs, and the one of the shorter-wavelength mode is 5.8 fs. We attribute the variation of the dephasing time to different coupling strength between the two modes at different delay times. This study may further promote the application of plasmons in the fields of surface-enhanced Raman scattering and plasmon assisted catalysis.
{"title":"Near-field control of gold nanostructure by the interaction of SPP and incident light","authors":"Wang Yue, Wang Lun, Sun Baixun, Lang Peng, Xu Yang, Zhao Zhenlong, Song Xiaowei, Ji Boyu, Lin Jingquan","doi":"10.7498/aps.72.20230514","DOIUrl":"https://doi.org/10.7498/aps.72.20230514","url":null,"abstract":"Localized Surface Plasmon (LSP) in nanostructure excited by Surface Plasmon Polariton (SPP) corresponds to stronger near-field enhancement and special spectral and dynamic responses that provides a new path to explore the interaction between light and matter. Meanwhile, this scheme can also release the signal background noise and structural thermal effect, and improve the performance of plasmonic components and sensing detectors based on LSP. However, the current research on this aspect is still insufficient. In this paper, we investigated the near-field characteristics of a plasmon composite structure composed of plasmon focusing lens and gold nanorod under the excitation of dual-beam using Finite-Difference Time-Domain (FDTD) method. The result shows that the near-field intensity control on the upper surface and in the gap position of the nanorod can be achieved by adjusting the relative time delay between the first light beam (used to excite SPP) and the second light beam (used to excite LSP). Specifically, the maximum adjustment range of the near-field intensity corresponding to 770 nm resonant mode in the gap position is about 23, and the adjustment period is about 2.4 fs. In a resonant mode dominated by SPP at a wavelength of 999 nm, the near-field intensity adjustment range is as small as 6, and the adjustment period is about 4 fs. On the upper surface of the structure, the adjustment range of the near-field intensity of the two resonant modes (719 nm and 802 nm) is basically the same (about 15), and the adjustment period is 2.4 fs and 2.8 fs. The achievement of the near field control is attributed to the coherent superposition of SPP-excited LSP with light-excited LSP. In addition, the dephasing time of the coupling field was investigated using quasi- normal mode. It is found that the nanorod structure will correspond to different dephasing time under different relative time delay between two excitation light beams. Specifically, for the time delay of 0.72 fs (Δt=0.72 fs), the corresponding dephasing time for both modes is the same of 6.0 fs. For Δt=1.92 fs, the dephasing time of the longer-wavelength mode is 7.1 fs, and the one of the shorter-wavelength mode is 5.8 fs. We attribute the variation of the dephasing time to different coupling strength between the two modes at different delay times. This study may further promote the application of plasmons in the fields of surface-enhanced Raman scattering and plasmon assisted catalysis.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74771382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wave-wave resonance mechanism plays a fundamental and prominent role in the process of energy transmission and distribution in whether microscopic or macroscopic materials. For the most extensive and intuitive ocean surface wave motion on earth, it is bound to be even more so. Can we extract the general wave-wave resonance law from it? Especially the most special and brief resonance one for single wave train. To this end, according to a set of classical methods proposed by Phillips for initiating modern water wave dynamics with the specific 4-wave resonance conditions, and starting from the basic governing equations of ocean deep-water surface capillary-gravity waves, the first-order differential equation of the Fourier component of free surface displacement and the second-, third- and fourth-order integral differential ones which are becoming more and more complex but tend to be complete are given in turn by the Fourier-Stieltjes transformation and perturbation method. Under a set of symbol system which are self-created, self-evident and concise, these equations are solved in turn to obtain the first-order free surface displacement of single wave train, the Fourier coefficients of the second-, third- and fourth-order non-resonant and resonant free surface ones and the second-, third- and fourth-order resonant conditions, thus leading to the general nth-order self-resonance law of single wave train. This completely reveals the rich connotation of single wave resonance dynamics of ocean surface capillary-gravity waves, effectively expands the application range of the classical single wave resonance solutions given by Phillips for ocean surface gravity waves, lays the foundation for depicting single and multiple resonance interaction mechanisms of double and multi-wave trains of ocean surface waves, and so provides a typical example for the exploration of single-wave resonance law in all wave fields.
{"title":"The nth-order self-resonance law of single wave train for surface capillary-gravity waves in deep water","authors":"Huang Hu, Tian Ze-Bing","doi":"10.7498/aps.72.20221281","DOIUrl":"https://doi.org/10.7498/aps.72.20221281","url":null,"abstract":"Wave-wave resonance mechanism plays a fundamental and prominent role in the process of energy transmission and distribution in whether microscopic or macroscopic materials. For the most extensive and intuitive ocean surface wave motion on earth, it is bound to be even more so. Can we extract the general wave-wave resonance law from it? Especially the most special and brief resonance one for single wave train. To this end, according to a set of classical methods proposed by Phillips for initiating modern water wave dynamics with the specific 4-wave resonance conditions, and starting from the basic governing equations of ocean deep-water surface capillary-gravity waves, the first-order differential equation of the Fourier component of free surface displacement and the second-, third- and fourth-order integral differential ones which are becoming more and more complex but tend to be complete are given in turn by the Fourier-Stieltjes transformation and perturbation method. Under a set of symbol system which are self-created, self-evident and concise, these equations are solved in turn to obtain the first-order free surface displacement of single wave train, the Fourier coefficients of the second-, third- and fourth-order non-resonant and resonant free surface ones and the second-, third- and fourth-order resonant conditions, thus leading to the general nth-order self-resonance law of single wave train. This completely reveals the rich connotation of single wave resonance dynamics of ocean surface capillary-gravity waves, effectively expands the application range of the classical single wave resonance solutions given by Phillips for ocean surface gravity waves, lays the foundation for depicting single and multiple resonance interaction mechanisms of double and multi-wave trains of ocean surface waves, and so provides a typical example for the exploration of single-wave resonance law in all wave fields.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72975561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shou Qi-Ye, Zhao Jie, Xu Hao-Jie, Li Wei, Wang Gang, Tang Ai-Hong, Wang Fu-Qiang
In quantum chromodynamics, the interactions of quarks with the topological gluon fields can lead to local P and CP violations, which may provide a solution to the strong CP problem and a possibility to explain the asymmetry of matterantimatter in the current universe. Under a strong magnetic field, the P and CP violations will lead to the separation of particles according to their electric charges, which is called the chiral magnetic effect (CME). An observation of the CMEinduced charge separation would confirm several fundamental properties of QCD, namely, approximate chiral symmetry restoration, topological charge fluctuations, and local parity violation. In relativistic heavy-ion collisions, there are other chiral anomalous effects similar to the CME, such as the chiral vortical effect (CVE), and the chiral magnetic wave (CMW). This review briefly summarizes the current experimental progress of the CME, CVE, and CMW searches in relativistic heavyion collisions.
{"title":"Progress on the experimental search for CME, CVE, and CMW","authors":"Shou Qi-Ye, Zhao Jie, Xu Hao-Jie, Li Wei, Wang Gang, Tang Ai-Hong, Wang Fu-Qiang","doi":"10.7498/aps.72.20230109","DOIUrl":"https://doi.org/10.7498/aps.72.20230109","url":null,"abstract":"In quantum chromodynamics, the interactions of quarks with the topological gluon fields can lead to local P and CP violations, which may provide a solution to the strong CP problem and a possibility to explain the asymmetry of matterantimatter in the current universe. Under a strong magnetic field, the P and CP violations will lead to the separation of particles according to their electric charges, which is called the chiral magnetic effect (CME). An observation of the CMEinduced charge separation would confirm several fundamental properties of QCD, namely, approximate chiral symmetry restoration, topological charge fluctuations, and local parity violation. In relativistic heavy-ion collisions, there are other chiral anomalous effects similar to the CME, such as the chiral vortical effect (CVE), and the chiral magnetic wave (CMW). This review briefly summarizes the current experimental progress of the CME, CVE, and CMW searches in relativistic heavyion collisions.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73151503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-energy nuclear physics aims at exploring and understanding the physics of matter constituted by quark and gluon. However, it is intrinsically diffculty to simulate high-energy nuclear physics from the first principle based on quantum chromodynamics with classical computers. In recent years, quantum computing has received intensive attention because it is expected to provide an ultimate solution for simulating high-energy nuclear physics. In this paper, we firstly review recent advances in quantum simulation of high-energy nuclear physics. Then some standard quantum algorithms will be introduced, such as state preparation and measurements of light-cone correlation function. Lastly, we demonstrate the advantage of quantum computing for solving the real-time evolution and the sign problems by studying hadronic scattering amplitude and phase structure of finitetemperature and finite-density matter, respectively.
{"title":"High-energy nuclear physics by quantum computing","authors":"Li Tian-Yin, Xing Hong-Xi, Zhang Dan-Bo","doi":"10.7498/aps.72.20230907","DOIUrl":"https://doi.org/10.7498/aps.72.20230907","url":null,"abstract":"High-energy nuclear physics aims at exploring and understanding the physics of matter constituted by quark and gluon. However, it is intrinsically diffculty to simulate high-energy nuclear physics from the first principle based on quantum chromodynamics with classical computers. In recent years, quantum computing has received intensive attention because it is expected to provide an ultimate solution for simulating high-energy nuclear physics. In this paper, we firstly review recent advances in quantum simulation of high-energy nuclear physics. Then some standard quantum algorithms will be introduced, such as state preparation and measurements of light-cone correlation function. Lastly, we demonstrate the advantage of quantum computing for solving the real-time evolution and the sign problems by studying hadronic scattering amplitude and phase structure of finitetemperature and finite-density matter, respectively.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72706742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Graphene-based van der Waals heterojunctions can not only modulate the electronic properties of graphene but also retain the superior properties of the original monolayer. In this paper, the structure, electrical contact types, electronic and optical properties of Graphene/C3N van der Waals heterojunctions are systematically investigated based on first-principles calculations. We find that there is a p-type Schottky contact of only 0.039 eV in the Graphene/C3N van der Waals heterojunctions at the equilibrium state. The external electric field can adjust the interface contact type, from p-type to n-type schottky contact, or from p-type schottky contact to ohmic contact. The vertical strain not only opens a nonnegligible band gap of 360 meV at the Dirac cone of Graphene in Graphene/C3N van der Waals heterojunctions, but also modulates the band gap of C3N in the heterojunctions. Moreover, both the doping type and concentration of the carrier can be effectively tuned by the applied electric field and the vertical strain. The increase in carrier concentration is more pronounced by the applied electric field. Compared with the pristine monolayer Graphene and monolayer C3N, the optical response range and the light absorption rate of Graphene/C3N van der Waals heterojunctions are enhanced. Main absorption peak in the spectrum up to 106 cm-1. These results not only provide valuable theoretical guidance for the design of Schottky-based Graphene/C3N van der Waals heterojunctions devices, but also further explore the potential of heterojunctions for further applications in optoelectronic nanodevices and field-effect transistor devices.
石墨烯基范德华异质结不仅可以调制石墨烯的电子特性，还可以保留原有单层石墨烯的优越性能。本文基于第一性原理计算系统地研究了石墨烯/C3N范德华异质结的结构、电接触类型、电子和光学性质。我们发现石墨烯/C3N范德华异质结在平衡状态下存在一个p型肖特基接触，只有0.039 eV。外加电场可以调节界面接触类型，从p型肖特基接触到n型肖特基接触，或从p型肖特基接触到欧姆接触。在石墨烯/C3N范德华异质结中，垂直应变不仅在石墨烯的狄拉克锥上打开了一个不可忽略的360 meV带隙，而且还调节了C3N在异质结中的带隙。此外，外加电场和垂直应变可以有效地调节载流子的掺杂类型和浓度。外加电场使载流子浓度的增加更为明显。与原始单层石墨烯和单层C3N相比，石墨烯/C3N van der Waals异质结的光响应范围和光吸收率都有所提高。光谱中主要吸收峰高达106 cm-1。这些结果不仅为基于schottkey的石墨烯/C3N范德华异质结器件的设计提供了有价值的理论指导，而且进一步探索了异质结在光电纳米器件和场效应晶体管器件中的进一步应用潜力。
{"title":"Tunable electronic structures and interface contact in graphene/C3N van der Waals heterostructures","authors":"Huang Min, Li ZhanHai, Cheng Fang","doi":"10.7498/aps.72.20230318","DOIUrl":"https://doi.org/10.7498/aps.72.20230318","url":null,"abstract":"Graphene-based van der Waals heterojunctions can not only modulate the electronic properties of graphene but also retain the superior properties of the original monolayer. In this paper, the structure, electrical contact types, electronic and optical properties of Graphene/C3N van der Waals heterojunctions are systematically investigated based on first-principles calculations. We find that there is a p-type Schottky contact of only 0.039 eV in the Graphene/C3N van der Waals heterojunctions at the equilibrium state. The external electric field can adjust the interface contact type, from p-type to n-type schottky contact, or from p-type schottky contact to ohmic contact. The vertical strain not only opens a nonnegligible band gap of 360 meV at the Dirac cone of Graphene in Graphene/C3N van der Waals heterojunctions, but also modulates the band gap of C3N in the heterojunctions. Moreover, both the doping type and concentration of the carrier can be effectively tuned by the applied electric field and the vertical strain. The increase in carrier concentration is more pronounced by the applied electric field. Compared with the pristine monolayer Graphene and monolayer C3N, the optical response range and the light absorption rate of Graphene/C3N van der Waals heterojunctions are enhanced. Main absorption peak in the spectrum up to 106 cm-1. These results not only provide valuable theoretical guidance for the design of Schottky-based Graphene/C3N van der Waals heterojunctions devices, but also further explore the potential of heterojunctions for further applications in optoelectronic nanodevices and field-effect transistor devices.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74567220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wang Li-na, Chen Li, Sheng Min-Jia, Wang Lei-Lei, Cui Hai-Hang, Zheng Xu, Huang Min-Hua
Self-propelled micromotors serve as a bridge between the microfluidic environments and macroscopic control. They have broad application prospects in targeted drug delivery, biosensors, and other fields. The high driving speed of bubble micromotors is an irreplaceable advantage in practical applications. Bubble micromotors convert chemical energy in ambient solutions into mechanical energy through asymmetric surface catalytic reactions to drive their own motion. The energy conversion rate of bubble driving is used as an indicator to evaluate the driving force. The Pt catalytic layer of a tubular micromotor is located on the inner wall of the microtube. Bubbles form inside the tube. It is released from one end of the microtubule into the solution and self driven by bubble rebound, with an energy conversion rate of ~10-10. The Janus microsphere motor near the gas-liquid interface utilizes the energy of the bubble coalesced with the interface to drive the microsphere, with an energy conversion rate of ~10-7. In sum, the tubular bubble motor is suitable for complex scenarios but has low energy conversion rate. The Janus microsphere motor driven by bubbles has high efficiency but is only suitable near the gas-liquid interface. This paper combines the advantages of driving tubular micromotors in bulk solution and Janus microsphere motors utilizing interface energy to efficiently drive, proposing a new method of dual bubble coalescence and driving Janus microsphere motors. In the experiment, a high-speed camera was used to record the ~100μs of dual bubble coalescence and the process of driving micromotors. Then we investigates the initial kinetic energy conversion rate of micro motors driven by bubble coalescence. Three sets of different bubble/particle size ratios of Rb/Rp<1, Rb/Rp≈1, Rb/Rp>1 were presented for their propulsion effects on microspheres. The initial kinetic energy conversion rate was defined to characterize the contribution of bubble coalescence process to microsphere driving. After simulations with the pseudo potential lattice Boltzmann method, the mechanism of bubble coalescence driving the motion of microspheres was revealed. It is clarified that the interface oscillation caused by bubble coalescence is the main reason driving the micromotor, and its energy conversion rate is between the rebound driving of the tubular micromotor and the one-bubble coalescence driving with the freesurface. The research results revealed the details of bubble coalescence at different time periods, and provided the effects of factors such as bubble particle size ratio on microsphere displacement and initial kinetic energy conversion rate. It confirmed the efficient driving mechanism of dual bubble coalescence and release of surface energy.
{"title":"Study on the mechanism of the interface evolution of dual-bubble coalescence driving micromotors in bulk phase","authors":"Wang Li-na, Chen Li, Sheng Min-Jia, Wang Lei-Lei, Cui Hai-Hang, Zheng Xu, Huang Min-Hua","doi":"10.7498/aps.72.20230608","DOIUrl":"https://doi.org/10.7498/aps.72.20230608","url":null,"abstract":"Self-propelled micromotors serve as a bridge between the microfluidic environments and macroscopic control. They have broad application prospects in targeted drug delivery, biosensors, and other fields. The high driving speed of bubble micromotors is an irreplaceable advantage in practical applications. Bubble micromotors convert chemical energy in ambient solutions into mechanical energy through asymmetric surface catalytic reactions to drive their own motion. The energy conversion rate of bubble driving is used as an indicator to evaluate the driving force. The Pt catalytic layer of a tubular micromotor is located on the inner wall of the microtube. Bubbles form inside the tube. It is released from one end of the microtubule into the solution and self driven by bubble rebound, with an energy conversion rate of ~10-10. The Janus microsphere motor near the gas-liquid interface utilizes the energy of the bubble coalesced with the interface to drive the microsphere, with an energy conversion rate of ~10-7. In sum, the tubular bubble motor is suitable for complex scenarios but has low energy conversion rate. The Janus microsphere motor driven by bubbles has high efficiency but is only suitable near the gas-liquid interface. This paper combines the advantages of driving tubular micromotors in bulk solution and Janus microsphere motors utilizing interface energy to efficiently drive, proposing a new method of dual bubble coalescence and driving Janus microsphere motors. In the experiment, a high-speed camera was used to record the ~100μs of dual bubble coalescence and the process of driving micromotors. Then we investigates the initial kinetic energy conversion rate of micro motors driven by bubble coalescence. Three sets of different bubble/particle size ratios of Rb/Rp<1, Rb/Rp≈1, Rb/Rp>1 were presented for their propulsion effects on microspheres. The initial kinetic energy conversion rate was defined to characterize the contribution of bubble coalescence process to microsphere driving. After simulations with the pseudo potential lattice Boltzmann method, the mechanism of bubble coalescence driving the motion of microspheres was revealed. It is clarified that the interface oscillation caused by bubble coalescence is the main reason driving the micromotor, and its energy conversion rate is between the rebound driving of the tubular micromotor and the one-bubble coalescence driving with the freesurface. The research results revealed the details of bubble coalescence at different time periods, and provided the effects of factors such as bubble particle size ratio on microsphere displacement and initial kinetic energy conversion rate. It confirmed the efficient driving mechanism of dual bubble coalescence and release of surface energy.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74570052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flexible electronics are of great interest to researchers because of their wide applications such as information storage, energy harvesting and wearable device. To realize extraordinary functionalities, freestanding single crystal oxide thin film is applied due to its super elasticity, easy-to-transfer, and outstanding ferro/electric/magnetic properties. Owing to state-of-art synthesis methods, functional oxide film of various materials can be obtained in freestanding phase, which eliminates the restrictions from growth substrate and can be transferal to other flexible layers. In this paper, we firstly introduce wet etching and mechanical exfoliation methods applied to prepare freestanding single crystal oxide thin film, then review their applications in ferroelectric memory, piezoelectric energy harvester, dielectric energy storage, correlated oxide interface, and novel freestanding oxide structure. Summary of recent research progress and future outlooks are finally discussed.
{"title":"Research progress of applications of freestanding single crystal oxide thin film","authors":"Ruobo Peng, Guohua Dong, Ming Liu","doi":"10.7498/aps.72.20222382","DOIUrl":"https://doi.org/10.7498/aps.72.20222382","url":null,"abstract":"Flexible electronics are of great interest to researchers because of their wide applications such as information storage, energy harvesting and wearable device. To realize extraordinary functionalities, freestanding single crystal oxide thin film is applied due to its super elasticity, easy-to-transfer, and outstanding ferro/electric/magnetic properties. Owing to state-of-art synthesis methods, functional oxide film of various materials can be obtained in freestanding phase, which eliminates the restrictions from growth substrate and can be transferal to other flexible layers. In this paper, we firstly introduce wet etching and mechanical exfoliation methods applied to prepare freestanding single crystal oxide thin film, then review their applications in ferroelectric memory, piezoelectric energy harvester, dielectric energy storage, correlated oxide interface, and novel freestanding oxide structure. Summary of recent research progress and future outlooks are finally discussed.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72370335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnetic islands produced in toroidal magnetic confinement plasma has a three-dimensional helical structure because of the rotational transform, especially the equilibrium magnetic surface of the stellarator is three-dimensional helical structure. Thus, the formation and instability of the magnetic island of the Stellarator is a typical issue of the three-dimensional physics and is also one of the key topics of the physics research of the Stellarator. Magnetic islands and related tearing mode physics are major issues in stellarator. The non-inductively current drive, i.e. electron cyclotron current drive (ECCD) can be used as one of the approaches to adjust the rotational transform, and hence, affecting the generation of magnetic islands. In this study, we have applied additional toroidal magnetic field to generate m/n=5/2 magnetic islands in the low β operation on the Chinese First Quasi-axisymmetric Stellarator (CFQS) so that the influence of the bootstrap current is negligible. Then, we have investigated the suppression mechanism of magnetic islands in low β plasmas using the HINT code. It is found that in case of the constant current, when current direction is positive, with increasing current the width of islands increases. When the direction of current is reversed, the island is suppressed with the amplitude of the current >6kA. The main reason is that the rotational transform is away from iota=0.4 rational surface and the m/n=5/2 magnetic island does not meet the resonance conditions. In case of local current profile, the magnetic island width decreases as a result of the enhanced magnetic shear at iota=0.4 rational surface. Moreover, effects of the direction and the amplitude of the current on the suppression of magnetic islands have been discussed in more detail.
{"title":"Studies on the suppression mechanism of equilibrium magnetic islands in CFQS low-β plasmas","authors":"Su Xiang, Wang Xian-Qu, Fu Tian, Xu Yu-hong","doi":"10.7498/aps.72.20230546","DOIUrl":"https://doi.org/10.7498/aps.72.20230546","url":null,"abstract":"Magnetic islands produced in toroidal magnetic confinement plasma has a three-dimensional helical structure because of the rotational transform, especially the equilibrium magnetic surface of the stellarator is three-dimensional helical structure. Thus, the formation and instability of the magnetic island of the Stellarator is a typical issue of the three-dimensional physics and is also one of the key topics of the physics research of the Stellarator. Magnetic islands and related tearing mode physics are major issues in stellarator. The non-inductively current drive, i.e. electron cyclotron current drive (ECCD) can be used as one of the approaches to adjust the rotational transform, and hence, affecting the generation of magnetic islands. In this study, we have applied additional toroidal magnetic field to generate m/n=5/2 magnetic islands in the low β operation on the Chinese First Quasi-axisymmetric Stellarator (CFQS) so that the influence of the bootstrap current is negligible. Then, we have investigated the suppression mechanism of magnetic islands in low β plasmas using the HINT code. It is found that in case of the constant current, when current direction is positive, with increasing current the width of islands increases. When the direction of current is reversed, the island is suppressed with the amplitude of the current >6kA. The main reason is that the rotational transform is away from iota=0.4 rational surface and the m/n=5/2 magnetic island does not meet the resonance conditions. In case of local current profile, the magnetic island width decreases as a result of the enhanced magnetic shear at iota=0.4 rational surface. Moreover, effects of the direction and the amplitude of the current on the suppression of magnetic islands have been discussed in more detail.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73607884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semiconductor quantum dot qubits are one of the most promising candidates for quantum computing. Among them, singlet-triplet qubits have attracted much attention due to their excellent properties of all-electric control and accurate readout. To improve qubitimmunity to charge noise, strong driving pulses are usually introduced to make operation as fast as possible. However, the complex dynamics induced by strong driving pulses make the rotational wave approximation inapplicable and hinder the implementation of high-fidelity qubit operation. In this work, we present a method utilizing simple quadrature pulses to correct errors of high-frequency oscillatory terms induced by strong driving. A scheme to obtain these pulses is proposed based on a full quantization of the system and Derivative Removal by Adiabatic Gate (DRAG) theory, as the former clarify the elementary processes of strong driving effects and enable the latter to find correction pulse shapes. The numerical stimulation results show that, with the help of the control pulses of this method, a NOT gate with 99.99% fidelity and gate time as low as 2 ns can be achieved, which indicates that the control error brought by strong driving is no longer a limiting factor. In particular, NOT gate fidelity higher than 99.9% is achievable even when the charge noise is in the level of 2 μeV. Notice that this method can be applied for any resonant-driving single-qubit rotation and not just NOT gates. Therefore, our approach will facilitate qubits to realize fast, high-fidelity single-qubit gates under charge noise.
{"title":"High-fidelity single-qubit gates of a strong driven singlet-triplet qubit","authors":"Liu Qi-Pei, Zhang Cheng-Xian, Xue Zheng-Yuan","doi":"10.7498/aps.72.20230906","DOIUrl":"https://doi.org/10.7498/aps.72.20230906","url":null,"abstract":"Semiconductor quantum dot qubits are one of the most promising candidates for quantum computing. Among them, singlet-triplet qubits have attracted much attention due to their excellent properties of all-electric control and accurate readout. To improve qubitimmunity to charge noise, strong driving pulses are usually introduced to make operation as fast as possible. However, the complex dynamics induced by strong driving pulses make the rotational wave approximation inapplicable and hinder the implementation of high-fidelity qubit operation. In this work, we present a method utilizing simple quadrature pulses to correct errors of high-frequency oscillatory terms induced by strong driving. A scheme to obtain these pulses is proposed based on a full quantization of the system and Derivative Removal by Adiabatic Gate (DRAG) theory, as the former clarify the elementary processes of strong driving effects and enable the latter to find correction pulse shapes. The numerical stimulation results show that, with the help of the control pulses of this method, a NOT gate with 99.99% fidelity and gate time as low as 2 ns can be achieved, which indicates that the control error brought by strong driving is no longer a limiting factor. In particular, NOT gate fidelity higher than 99.9% is achievable even when the charge noise is in the level of 2 μeV. Notice that this method can be applied for any resonant-driving single-qubit rotation and not just NOT gates. Therefore, our approach will facilitate qubits to realize fast, high-fidelity single-qubit gates under charge noise.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72399469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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