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1.
ZHAN You-Bang ZHOU Ping FU Hao 《理论物理通讯》2004,42(12)
Dynamic evolution of a mesoscopic Josephson junction (M J J) interacting with excited even and odd coherent states is studied. It is shown that the supercurrent in MJJ exhibits both collapse and revival (CR) phenomenon and squeezing effect. It is also shown that the CR and squeezing of supercurrent are related to degree of excitation and average photon number. 相似文献
2.
In this paper, we study the supercurrent in a mesoscopic Josephson junction (MJJ) and its quantum statistical properties in the presence of nonclassical light fields. We investigate in detail the influence of external nonclassical light fields on current-voltage step structures of the MJJ. We also study in detail quantum statistical properties of the supercurrent when the external quantum electromagnetic fields are even and odd coherent-sta!e light fields. It is shown that the supercurrent in the MJJ exhibits both squeezing effect and quantum coherence. It is demonstrated that the MJJ can feel the difference not only between classical light fields and nonclassical light fields but also between different nonclassical light fields. 相似文献
3.
本文研究介观 Josephson 结与激发偶奇相干态的相互作用。研究了存在非经典光场时介观 Josephson 结中超导电流的一些特性,诸如崩塌与复苏现象,流压台阶特性,直流分量涨落以及超导电流的量子相干等。结果显示,超导电流的涨落及期望值可呈现直流分量。结果还显示稳态超导电流量,超导电流涨落的直流分量以及超导电流直流分量的关联函数等皆与光场的相位有关。 相似文献
4.
Mesoscopic Josephson junctions in the presence of two-mode quantized electromagnetic field 总被引:2,自引:0,他引:2
Dynamic behavior of a mesoscopic Josephson junction in the presence of a two-mode quantized electromagnetic field is investigated. It is shown that the currentvoltage- step structures depend apparently on the two basic frequencies of the two-mode field. The voltage jumps are generally not equidistant. It is also shown that for the correlated two-mode squeezed state the time evolution of the supercurrent exhibits quantum collapse and revival(CR) phenomenon, while for the noncorrelated two-mode coherent state the phenomenon does not occur. 相似文献
5.
Kerr偶奇相干态及其非经典性 总被引:6,自引:0,他引:6
本文对Ker偶奇相干态及其非经典性质进行了研究。结果表明:Kerr偶相干态可呈现周期性的二阶压缩效应,Kerr奇相干态则不存在这种压缩效应;但两者均可呈现周期性的振幅平方压缩效应,这与通常偶奇相干态的情形有所不同。 相似文献
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7.
The Squeezing and sub-poissonian photon statistics of an optical field are a purely quantum mechanical phenomenon and has
been accepted as means of achieving noise below the quantum shot-noise limit. The effect of higher-order squeezing and sub-poissonian
nature of an optical field in coherent anti-Stokes Raman scattering (CARS) and coherent anti-Stokes hyper Raman scattering
(CAHRS) are investigated under short-time approximation. The coupled Heisenberg equations of motion involving real and imaginary
parts of the quadrature operators are established and solved under short-time scale. The dependence of squeezing on the number
of photons is also investigated. It is also shown that higher-order squeezing allows a much larger fractional noise reduction
than lower-order squeezing. The occurrence of amplitude squeezing effects of the radiation field in the fundamental mode is
investigated in both the processes. The present work shows that squeezing is greater in CAHRS than the corresponding squeezing
in CARS. It is also shown that squeezing is greater in stimulated process than corresponding squeezing in spontaneous interaction.
The conditions for obtaining maximum and minimum squeezing are obtained. The photon statistics of the pump mode in the processes
has also been investigated and found to be sub-poissonian in nature. 相似文献
8.
证明了高阶振幅压缩的概念可以应用于q变形代数的光场。q变形算符aN 的正交归一本征态的压缩特点由这些态的内部奇偶结构决定。破坏这种奇偶结构将得到具有新压缩特点的光场。 相似文献
9.
We propose a scheme to coherently control spin squeezing of atomic Bose-Einstein condensate (BEC) via the technique of electromagnetically induced transparency (EIT). We study quantum dynamics of the mean spin vector and spin squeezing. It is shown that the mean spin vector and spin squeezing of the BEC can be controlled and manipulated by adjusting the external coupling fields or/and internal nonlinear interactions of the BEC. It is indicated that the spin squeezing can be generated rapidly in the dynamical process and maintained in a long time interval. It is found that a larger effective Rabi coupling between atoms and lasers can produce a stronger spin squeezing, and the squeezing can maintain a longer time interval. 相似文献
10.
It is shown that an anomaly exists for the supercurrent of the supersymmetric vector multiplet when coupled to external supergravity fields. As a result, this anomaly will also be present in at least one of the O(1), O(2), or O(3) extended supergravity models. 相似文献
11.
It has been common knowledge that the single-mode squeezing operator and the two-mode squeezing operator are independent of each other. However, in this work we find that after using the technique of integration within Ω-ordering and β-ordering, we can detach two single-mode squeezing operators from the two-mode squeezing operator. In other words, we show that the two-mode squeezing operator can be split into a β-ordered two-mode squeezing operator (with a new squeezing parameter) and two single-mode squeezing operators (with another squeezing parameter). This tells us that the two-mode squeezing mechanism also involves some single-mode squeezing. 相似文献
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13.
计算表明,与场的相干态类似的原子相干态,具有不同于场的相干态的压缩行为;进一步证明:直接类比于(?)(ξ)不能得到“原子压缩算符”. 相似文献
14.
We investigate the equilibrium spin transport in a ferromagnet/noncentrosymmetric superconductor (FM/NCS) junction where the NCS has a dominant triplet order parameter and helical edge state. Based on the symmetry analysis and numerical calculation, we demonstrate that there is a nonzero spin supercurrent flowing in the junction, which stems from the exchange coupling between the FM magnetization and triplet Cooper-pair spin. It is also found that a transverse spin current other than the helical edge spin current is flowing along the interface of the junction, and its polarization is related to the longitudinal spin supercurrent. Besides, an equilibrium Hall current is also shown to flow along the junction’s interface due to the broken time-reversal symmetry from the FM. 相似文献
15.
PropertiesofAmplitudeNth┐powerSqueezingofEvenandOddqs┐CoherentStatesWANGJisuo1)SUNChangyong1)HEJinyu2)(1)DepartmentofPhysics... 相似文献
16.
Song-Song Li 《International Journal of Theoretical Physics》2017,56(9):2825-2830
We investigate spin squeezing of the one-axis twisting model. By using short-time approximation solutions of the angular momentum operators, we analytically and numerically calculate the spin squeezing parameter. It is shown that smaller linear interaction can produce a stronger spin squeezing and maintain a longer time interval. It is also shown that the stronger spin squeezing can be achieved by increasing the number of particles. 相似文献
17.
We investigate spin squeezing of a collective spin system governed by mixed Hamiltonian of the one-axis twisting and two-axis counter-twisting with decay. The analytic solutions of the optimally squeezed angle and the spin squeezing parameter are derived. It is shown that the two-axis counter-twisting Hamiltonian induces stronger spin squeezing than the one-axis twisting one. It is also shown that the decay rate has no effect on the size of the squeezing parameter, it only affects the period of squeezing parameter. 相似文献
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19.
Xiao-Jie Yi Guo-Qiang Huang Jian-Min Wang 《International Journal of Theoretical Physics》2012,51(9):2960-2965
We investigate the spin squeezing in superpositions of a N-qubit GHZ state and two W states. The spin squeezing parameter is determined by the superposition coefficients and the relative phase. It is shown that there is squeezing in the n 2 direction and there is no squeezing in the n 1 direction. It is also shown that the state with more number of qubits has smaller spin squeezing parameter. 相似文献
20.
You-bang Zhan 《Physics letters. A》1991,160(6):498-502
The concept of amplitude-cubed squeezing is introduced and shown to be a nonclassical effect. It is shown that such squeezing may be generated in some nonlinear systems, such as second and third harmonic generations. In particular, the normal squeezing of the third harmonic depends directly upon the amplitude-cubed squeezing of the incident light in the fundamental mode. 相似文献