低杂波电流驱动(Lower Hybrid Current Drive,LHCD)是托卡马克的主要辅助加热与电流驱动方式之一,研究表明,低杂波在刮削层内的边界寄生效应会显著降低低杂波电流驱动效率。其中,边界密度涨落引起的波散射会导致刮削层内的低杂波波谱变...低杂波电流驱动(Lower Hybrid Current Drive,LHCD)是托卡马克的主要辅助加热与电流驱动方式之一,研究表明,低杂波在刮削层内的边界寄生效应会显著降低低杂波电流驱动效率。其中,边界密度涨落引起的波散射会导致刮削层内的低杂波波谱变化,从而改变低杂波功率沉积位置和电流驱动效率。本文使用全波解方法研究全超导托卡马克(Experimental Advanced Superconducting Tokamak,EAST)装置上刮削层内密度涨落导致的低杂波波散射,重点分析不同特征的低频电子密度涨落对波散射的影响。模拟结果表明:密度波包(blob)引起的散射导致低杂波功率流的空间结构的改变,blob造成的背向散射比前向散射更明显;blob内的密度涨落大小主要影响波场扰动幅度,blob的半径主要影响波散射的空间范围,多个blob造成的全场扰动显著增加。展开更多
According to the physical mechanism of the generation of the resistance or the electron phonon interaction, a new method is proposed to quantize the RLC electric circuit. Calculations show that the quantum fluctuatio...According to the physical mechanism of the generation of the resistance or the electron phonon interaction, a new method is proposed to quantize the RLC electric circuit. Calculations show that the quantum fluctuations under this new quantization are smaller than those by the traditional effective Hamiltonian method. And squeezed states can be generated if the inductance and capacity are time dependent. Meanwhile, the shortcoming of the traditional method that the electric charge and current will vanish in the long time limit is overcome.展开更多
We study the quantization of mesoscopic inductance coupling circuit and discuss its time evolution. Bymeans of the thermal field dynamics theory we study the quantum fluctuation of the system at finite temperature.
Mesoscopic damped mutual capacitance coupled double resonance circuit is quantized by the method of damped harmonic oscillator quantization. Hamiltonian is diagonalized by the method of unitary transformation. The ene...Mesoscopic damped mutual capacitance coupled double resonance circuit is quantized by the method of damped harmonic oscillator quantization. Hamiltonian is diagonalized by the method of unitary transformation. The energy spectra of this circuit are given. The quantum fluctuations of the charge and current of each loop are investigated by the method of thermo- field dynamics (TFD) in thermal excitation state,thermal squeezed vacuum state, thermal vacuum state and vacuum state. It is shown that the quantum fluctuations of the charge and current are related to not only circuit inherent parameter and coupled magnitude, but also quantum number of excitation, squeezed coefficients, squeezed angle and environmental temperature. And the quantum fluctuations increase with the increase of temperature and decay with time.展开更多
In this work, we discussed the stochastic thermodynamics of mesoscopic electron transfer reactions between ions and electrodes. With a relationship between the reaction rate con- stant and the electrode potential, we ...In this work, we discussed the stochastic thermodynamics of mesoscopic electron transfer reactions between ions and electrodes. With a relationship between the reaction rate con- stant and the electrode potential, we find that the heat dissipation βq equals to the dynamic irreversibility of the reaction system minus an internal entropy change term. The total en- tropy change Ast is defined as the summation of the system entropy change As and the heat dissipation/βq such that △st=△s＋βq. Even though the heat dissipation depends linearly on the electrode potential, the total entropy change is found to satisfy the fluctuation theo- rem 〈e-△st 〉=1, and hence a second law-like inequality reads （△st）≥0. Our study provides a practical methodology for the stochastic thermodynamics of electrochemical reactions, which may find applications in biochemical and electrochemical reaction systems.展开更多
Taking into account the combined effects of the external magnetic field, adiabatic dust charge fluctuation and collisions occurring between the charged dust grains and neutral gas particles （dust-neutral collisions）...Taking into account the combined effects of the external magnetic field, adiabatic dust charge fluctuation and collisions occurring between the charged dust grains and neutral gas particles （dust-neutral collisions）, the dust-acoustic solitary waves in three-dimensional uniform dusty plasmas are investigated analytically. By using the reductive perturbation method, the Korteweg-de Vries （KdV） equation governing the dnst-aconstic solitary waves is obtained. The present analytical results show that only rarefactive solitary waves exist in this system. It is also found that the effects of the wave vector along the z-direction, dust charge variation, collisional frequency, the plasma density, and temperature ratio can significantly influence the characteristics of low-frequency wave modes. Moreover, for the collisional dusty plasmas, there is a certain critical value μc of the plasma density ratio μ, if μ 〈 μc, the width of the waves increases with μ, otherwise the width of waves decreases with μ.展开更多
Herein we investigated the electronic properties of layered transition-metal oxides NazTi2Sb2O by 23Na nuclear magnetic reso- nance （NMR） measurement. The resistivity, susceptibility and specific heat measurements s...Herein we investigated the electronic properties of layered transition-metal oxides NazTi2Sb2O by 23Na nuclear magnetic reso- nance （NMR） measurement. The resistivity, susceptibility and specific heat measurements show a phase transition at approxi- mately 114 K （TA）. No splitting or broadening in the central line of 23Na NMR spectra is observed below and above the transi- tion temperature indicating no internal field being detected. The spin-lattice relaxation rate divided by T （I/T1T） shows a sharp drop at about 110 K which suggests a gap opening behavior. Below the phase transition temperature zone, I/T1T shows Fermi liquid behavior but with much smaller value indicating the loss of large part of electronic density of states （DOS） because of the gap. No signature of the enhancement of spin fluctuations or magnetic order is found with the decreasing temperature. These results suggest a commensurate charge-density-wave （CDW） phase transition occurring.展开更多
In this work,we theoretically study hard-core bosons on a two-dimensional square optical superlattice at T = 0.First of all,we present the mean field phase diagram of this model in terms of the chemical potential μ a...In this work,we theoretically study hard-core bosons on a two-dimensional square optical superlattice at T = 0.First of all,we present the mean field phase diagram of this model in terms of the chemical potential μ and the alternating potential strength △.Besides a superfluid(SF) phase at △ = 0 and a charge density wave(CDW)phase in the large △ at half filling,we demonstrate that a supersolid(SS) phase emerges in the moderate △.Then,we focus on the μ = 0,e.g.,half filling case,using large-S semi-classical spin-wave approximation to study the SS to CDW quantum phase transition.In particular,we calculate the ground-state energy and the superfluid density at the level of1/S correction.We then compare the spin-wave results with the large scale quantum Monte Carlo(QMC) simulations using the cluster stochastic series expansion(CSSE) algorithm,and find that while the spin wave method is intuitive with clear physical pictures,the quantum critical point is quite different from that of numerical results which is believed to be accurate.We suggest that as simple as it is,this model still exhibits strong quantum fluctuations near the quantum critical point beyond the power of semiclassical spin-wave approach.展开更多
文摘According to the physical mechanism of the generation of the resistance or the electron phonon interaction, a new method is proposed to quantize the RLC electric circuit. Calculations show that the quantum fluctuations under this new quantization are smaller than those by the traditional effective Hamiltonian method. And squeezed states can be generated if the inductance and capacity are time dependent. Meanwhile, the shortcoming of the traditional method that the electric charge and current will vanish in the long time limit is overcome.
文摘We study the quantization of mesoscopic inductance coupling circuit and discuss its time evolution. Bymeans of the thermal field dynamics theory we study the quantum fluctuation of the system at finite temperature.
基金the Natural Science Foundation of Heze University ofShandong Province, China (No.XY05WL01) and the UniversityExperimental Technology Foundation of Shandong Province, China(No.S04W138)
文摘Mesoscopic damped mutual capacitance coupled double resonance circuit is quantized by the method of damped harmonic oscillator quantization. Hamiltonian is diagonalized by the method of unitary transformation. The energy spectra of this circuit are given. The quantum fluctuations of the charge and current of each loop are investigated by the method of thermo- field dynamics (TFD) in thermal excitation state,thermal squeezed vacuum state, thermal vacuum state and vacuum state. It is shown that the quantum fluctuations of the charge and current are related to not only circuit inherent parameter and coupled magnitude, but also quantum number of excitation, squeezed coefficients, squeezed angle and environmental temperature. And the quantum fluctuations increase with the increase of temperature and decay with time.
基金supported by the National Natural Science Foundation of China(No.21403041 and No.21503048)the Startup Packages from Guizhou Education University
文摘In this work, we discussed the stochastic thermodynamics of mesoscopic electron transfer reactions between ions and electrodes. With a relationship between the reaction rate con- stant and the electrode potential, we find that the heat dissipation βq equals to the dynamic irreversibility of the reaction system minus an internal entropy change term. The total en- tropy change Ast is defined as the summation of the system entropy change As and the heat dissipation/βq such that △st=△s＋βq. Even though the heat dissipation depends linearly on the electrode potential, the total entropy change is found to satisfy the fluctuation theo- rem 〈e-△st 〉=1, and hence a second law-like inequality reads （△st）≥0. Our study provides a practical methodology for the stochastic thermodynamics of electrochemical reactions, which may find applications in biochemical and electrochemical reaction systems.
文摘Taking into account the combined effects of the external magnetic field, adiabatic dust charge fluctuation and collisions occurring between the charged dust grains and neutral gas particles （dust-neutral collisions）, the dust-acoustic solitary waves in three-dimensional uniform dusty plasmas are investigated analytically. By using the reductive perturbation method, the Korteweg-de Vries （KdV） equation governing the dnst-aconstic solitary waves is obtained. The present analytical results show that only rarefactive solitary waves exist in this system. It is also found that the effects of the wave vector along the z-direction, dust charge variation, collisional frequency, the plasma density, and temperature ratio can significantly influence the characteristics of low-frequency wave modes. Moreover, for the collisional dusty plasmas, there is a certain critical value μc of the plasma density ratio μ, if μ 〈 μc, the width of the waves increases with μ, otherwise the width of waves decreases with μ.
基金supported by the National Natural Science Foundation of China(Grant No.11025422)the National Basic Research Program of China(Grant No.2011CB921701)
文摘Herein we investigated the electronic properties of layered transition-metal oxides NazTi2Sb2O by 23Na nuclear magnetic reso- nance （NMR） measurement. The resistivity, susceptibility and specific heat measurements show a phase transition at approxi- mately 114 K （TA）. No splitting or broadening in the central line of 23Na NMR spectra is observed below and above the transi- tion temperature indicating no internal field being detected. The spin-lattice relaxation rate divided by T （I/T1T） shows a sharp drop at about 110 K which suggests a gap opening behavior. Below the phase transition temperature zone, I/T1T shows Fermi liquid behavior but with much smaller value indicating the loss of large part of electronic density of states （DOS） because of the gap. No signature of the enhancement of spin fluctuations or magnetic order is found with the decreasing temperature. These results suggest a commensurate charge-density-wave （CDW） phase transition occurring.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10904096,10604024,11474025the Natural Science Foundation of Beijing under Grant No.1092009
文摘In this work,we theoretically study hard-core bosons on a two-dimensional square optical superlattice at T = 0.First of all,we present the mean field phase diagram of this model in terms of the chemical potential μ and the alternating potential strength △.Besides a superfluid(SF) phase at △ = 0 and a charge density wave(CDW)phase in the large △ at half filling,we demonstrate that a supersolid(SS) phase emerges in the moderate △.Then,we focus on the μ = 0,e.g.,half filling case,using large-S semi-classical spin-wave approximation to study the SS to CDW quantum phase transition.In particular,we calculate the ground-state energy and the superfluid density at the level of1/S correction.We then compare the spin-wave results with the large scale quantum Monte Carlo(QMC) simulations using the cluster stochastic series expansion(CSSE) algorithm,and find that while the spin wave method is intuitive with clear physical pictures,the quantum critical point is quite different from that of numerical results which is believed to be accurate.We suggest that as simple as it is,this model still exhibits strong quantum fluctuations near the quantum critical point beyond the power of semiclassical spin-wave approach.
