共查询到20条相似文献,搜索用时 297 毫秒
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Prom investigation of the advantages and disadvantages of conventional tri-voltage method,a method for the measurement of the transmitting transducer’s impedance was presented to solve the difficult problem of examining the consistency of the transmitting phased array on the single-mode excitation sea spot.In the method based on the system function, the circuit structure of tri-voltage method was used but new parameters were measured.The principle of the method was given first.Then when resistors with different nominal values were used in the circuit,the measured results for the impedance of transducers were reported.The results were compared with the higher precision impedance analyzer.Finally,the error analysis was performed according to the impedance formula and the equivalent circuit parameters were fitted.Under the condition of guaranteeing the sampling precision,by performance analyzing, the resistor value in series was chosen relatively smaller than the impedance of transducer,the measurement of impedance could achieve the same precision as the higher precision impedance analyzer.Finally,the least squares curve-fitting of measured curves indicated that the transducer equivalent electrical parameters could be extracted accurately and used to design the matching network. 相似文献
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We use a semiclassical approximation to study the transport through the weakly open chaotic Sinai quantum billiards which can be considered as the schematic of a Sinai mesoscopic device,with the diffractive scatterings at the lead openings taken into account.The conductance of the ballistic microstructure which displays universal fluctuations due to quantum interference of electrons can be calculated by Landauer formula as a function of the electron Fermi wave number,and the transmission amplitude can be expressed as the sum over all classical paths connecting the entrance and the exit leads.For the Sinai billiards,the path sum leads to an excellent numerical agreement between the peak positions of power spectrum of the transmission amplitude and the corresponding lengths of the classical trajectories,which demonstrates a good agreement between the quantum theory and the semiclassical theory. 相似文献
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Wigner函数的负性是非经典量子态的重要判据之一.利用Fock态表象下Wigner函数的一般表达式,重构了相干态|z〉的k光子激发态|+k,z〉~a-k|z〉(k≥1)的Wigner函数,并根据其数值结果讨论了该量子态的非经典特性(这里a-1为Bose湮没算符的逆算符,其作用相当于Bose产生算符).结果表明,不论k取奇数还是偶数,相干态的这些k光子激发态都具有非经典特性;而且k的取值越大,这些量子态的非经典特性越明显.
关键词:
非经典量子态
激发相干态
Wigner函数
非经典特性 相似文献
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WANGDe-Hua DINGShi-Liang 《理论物理通讯》2003,40(6):702-706
Closed-orbit theory is a semiclassical technique for explaining the spectra of Rydberg atoms in external fields. Using the dosed-orblt theory and classical perturbation theory, we calculate the scaled recurrence spectra of Lithium atom in magnetic field plus a weak perpendicular electric field. The results show when the crossed electric field is added, the recurrence spectra are weakened greatly. As the scaled electric field f increases, the peaks of the recurrence spectra lose strength. Some recurrences are very sensitive and fall off rapidly as f increases, others persist till much higher f. As the electric field is stronger, some of the peaks revive. This phenomenon, caused by the interference among the electron waves that return to the nucleus, can be computed from the azimuthal dependence of the classical closed orbits. 相似文献
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量子力学矩阵元的经典极限 总被引:1,自引:0,他引:1
本研究了量子力学矩阵元的经典极限,用新的方法证明了如下定理;在分立谱情况下,量子力学矩阵元fnm的经典极限是相应经典力学量f(t)之Fourier级数展开的第n-m个分量;在连续谱情况下,量子力学矩阵元fEE与Plack常量h的乘积hfEE的经典极限相应经典力学量f(t)之Forier积分展开的第ω次分量。 相似文献
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高速带电粒子辐射的经典行为 总被引:1,自引:0,他引:1
给出了以任意速度运动的带电粒子辐射功率的严格表达式及做准周期运动时的辐射阻尼力公式,论证了在无外力作用时,有辐射行为的带电粒子不可能做速度和加速度能复原值的周期(或准周期)运动,得到了辐射粒子做直线运动时速度随时间的变化关系。 相似文献
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半经典近似:混沌运动的量子化 总被引:1,自引:0,他引:1
早期量子论的玻尔-索末菲规则对混沌运动失效,新的半经典近似从能级、本征态和状态的时间演化三个范畴上探讨了混沌运动的量子化,从而发展了“近代后量子力学”。 相似文献
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采用Thomas-Fermi近似势,将多电子系统简化为单电子问题,并用微扰论求解了Klein-Gordon方程.由电子的零级波函数求得了电荷密度和电流密度的零级表达式.通过适当简化Klein-Gordon方程,用分离变量和WKB近似,求得了电子波函数及相应的电荷密度与电流密度的表达式
关键词: 相似文献
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