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1.
In this paper the superpositions of two arbitrary coherent states |ψ〉 = α |β| + be^iψ |mβe^iδ〉 are constructed by using the superposition principle of quantum mechanics. The entropic squeezing effects of the quantum states are studied. The numerical results indicate that the amplitudes, the ratio between the amplitudes of two coherent states, the phase difference between the two components and the relative phase of the two coefficients play important roles in the squeezing effects of the position entropy and momentum entropy. 相似文献
2.
Vewinger F Heinz M Garcia Fernandez R Vitanov NV Bergmann K 《Physical review letters》2003,91(21):213001
We demonstrate experimental techniques for creating and measuring a coherent superposition of two degenerate atomic states with equal amplitudes in metastable neon. Starting from state (3)P(0), we create adiabatically a coherent superposition of the magnetic sublevels M=+/-1 of the state (3)P(2) using a tripod stimulated Raman adiabatic passage scheme. The measurement is based on the coupling of the levels (3)P(2)<-->(3)P(1) by a linearly polarized laser, followed by the detection of the population in the (3)P(2)(M=+/-2) states as a function of the polarization angle of that laser. 相似文献
3.
本文讨论了在双Λ型原子系统中制备相干叠加态的方法:一个Λ型系统通过控制激光而另一个Λ型系统采用部分受激拉曼绝热通道的方法.在理论上分析了产生任意相干叠加态的可能性并且讨论了透热系统在产生相干叠加态过程中的重要性.研究表明,没有透热过程是不可能制备出任意的叠加态.应用数值方法验证理论分析是正确,并且指出任意叠加态的产生只与控制脉冲的时间延迟有关. 相似文献
4.
We demonstrate that the maximum coherent superposition state can be selectively prepared using a sequence of pulse pairs in lambda-type atomic systems,with the final level as a doublet.In each pair,the Stocks pulse comes before the pump pulse,with their back edges overlapping.Numerical results indicate that by tuning the interval of the adjacent pulse pairs,the selective maximum coherent superposition state preparation between the initial and one of the final levels can be achieved.The phenomenon is caused by the accumulative property of the pulse sequence. 相似文献
5.
This paper discusses the amplitude-squared squeezing for the superposition of two coherent states with their phase differences being separately π/2, 3π/2, and π1, as well as for the superposition state of two pseudoclassical states. According to the analysis, it is found that the superposition state of two coherent states with their phase differences π/2 and 3π/2, and the superposition state of two pseudoclassical states both do exhibit the amplitude-squared squeezing. Also, some specific states are found to exhibit even stronger squeezing effects when relative phase of the superposition is equal to the average photon number. Amplitude-squared squeezing is dependent on the difference in phase between two coherent states. 相似文献
6.
This paper proposes a scheme to teleport an arbitrary multi-particle two-level atomic state between two parties or an arbitrary zero- and one-photon entangled state of multi-mode between two high-Q cavities in cavity QED. This scheme is based on the resonant interaction between atom and cavity and does not involve Bell-state measurement. It investigates the fidelity of this scheme and find out the case of this unity fidelity of this teleportation. Considering the practical case of the cavity decay, this paper finds that the condition of the unity fidelity is also valid and obtains the effect of the decay of the cavity on the successful probability of the teleportation. 相似文献
7.
根据Pegg-Barnett 相位定义,计算了一种新的非线性叠加相干态的相位概率分布函数和光子数-相位压缩效应,并进行了数值模拟. 相似文献
8.
It is shown that Gaussian superpositions of coherent states along an arc are approximate number-phase intelligent states associated with the Pegg-Barnett phase operator and describe amplitude squeezing. 相似文献
9.
We introduce a new entangled quantum state generated by applying single-mode coherent superposition of photon subtraction and addition (a† cos θ + a sin θ)m to the entangled coherent state |Ψ±(α,0)〉, and then investigate the entanglement properties affected by coherent superposition operation. It is shown that this operation can be applied to enhance the entanglement of the state |Ψ+(α,0)〉. In addition, the effects of the coherent operation is better to improve the entanglement than that of the creation operation (a†m) for |Ψ+(α,0)〉 in a small-amplitude regime and for |Ψ−(α,0)〉 in any regime. 相似文献
10.
ZOU Anhua 《Chinese Journal of Lasers》1994,3(2):117-127
ThenonclassicalpropertiesofthesuperpositioninvolvingtwosqueezingcoherentstatesZOUAnhua(DepartmentofPhysics,ShengraoTeacbors'C... 相似文献
11.
R. Paul 《Physics letters. A》1983,96(5):263-268
It is shown that Glauber-type coherent states exist in biological systems as a result of the broken symmetry of the free phonons. The symmetry of the system is reduced by the presence of the interaction terms in the hamiltonian. The coherent states so produced allow for the existence of giant dipoles capable of long-range interactions. 相似文献
12.
本文研究了一维模型分子离子(初态为基态和一个激发束缚态叠加的相干态)在超强超短激光脉冲作用下的谐波发射谱.我们发现在高次谐波谱平台区域出现了周期性的结构变化.我们利用小波变换对谐波谱进行了暂态时间频率分析,结果表明该谐波结构产生的原因是由电离电子返回母离子时与不同束缚态复合而产生的谐波光脉冲之间相干叠加.同时采用半经典计算,对所得到的计算结果进行了分析,验证了我们的结论. 相似文献
13.
We demonstrate a controlled phase change of π in a degenerate superposition by altering a laser frequency by only 10 MHz. The method relies on the preparation of an adiabatic state involving the M = ±2 and M = 0 states of the 3P2 (J = 2) level of metastable neon. Dependent on the frequency, the preparation proceeds either by stimulated Raman adiabatic passage (STIRAP) or by coherent population trapping (CPT). In the former case the superposition is prepared by adiabatic transfer induced in an extended tripod linkage scheme. In the latter case population is optically pumped into the Zeeman manifold of the level 3P2. The population which does not reach a dark state decays to the ground state of neon. The amplitudes and relative phases of the dark states differ for the two cases. The phase change is monitored using the method of phase-to-population mapping. 相似文献
14.
Diego Julio Cirilo-Lombardo 《Physics of Particles and Nuclei Letters》2014,11(4):502-505
New bounded coherent state construction, based in a Keldysh conjecture, is presented. The particular group structure arising from the model leads a new symmetry transformations for the coherent state system. The emergent new symmetry transformations are reminiscent of the Bogoliubov ones. This construction is applied to describe an excitonic system. We discuss how the symmetry of these transformations is intrinsically related with the stability and the behavior of the physical systems as in the excitonic case. 相似文献
15.
Zhen-Biao Yang 《Optics Communications》2008,281(10):2849-2853
A scheme is discussed for probabilistic teleportation of a special type of two-atom pure state - an arbitrary superposition of symmetric two-atom Dicke states. The scheme follows the previous idea [S.B. Zheng, Phys. Rev. A 69 (2004) 064302], which is proposed for approximate and probabilistic teleportation of an atomic state through only a detection on the sender atom. In principle, the present scheme can achieve faithful teleportation by resorting to a very different model, which depicts the resonant interaction of a Λ-type three-level atom with a two-mode cavity field. The scheme can also be used for teleportation of an arbitrary superposition of symmetric multi-atom Dicke states. 相似文献
16.
We propose a new scheme for generating the superposition and entanglement of the coherent states and squeezed states by considering N superconducting charge qubits (or artificial two-level atoms) interacting with photons in a high finesse cavity on a chip, assisted by a strong driving field. By virtue of the parameters of this system, we can generate novel quantum states, for example, multiparty entangled states and Schro¨dinger cat states among the superconducting qubits, coherent states and squeezed state... 相似文献
17.
R. Safaiee M. M. Golshan 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(4):457-463
The present work is concerned with an analysis of the entanglement between the electronic
coherent superpositions of spin states and subbands in a
quasi-one-dimensional Rashba nanoloop acted upon by a strong perpendicular magnetic field.
We explicitly include the confining potential and the Rashba spin-orbit coupling into the
Hamiltonian and then proceed to calculate the von Neumann entropy, a measure of
entanglement, as a function of time. An analysis of the von Neumann entropy demonstrates
that, as expected, the dynamics of entanglement strongly depends upon the initial state
and electronic subband excitations. When the initial state is a pure one formed by a
subband excitation and the z-component of spin states, the entanglement exhibits periodic
oscillations with local minima (dips). On the other hand, when the initial state is formed
by the subband states and a coherent superposition of spin states, the
entanglement still periodically oscillates, exhibiting stronger correlations, along with
elimination of the dips. Moreover, in the long run, the entanglement for the latter case
undergoes the phenomenon of collapse-revivals. This behaviour is absent for the first case
of the initial states. We also show that the degree of entanglement strongly depends upon
the electronic subband excitations in both cases. 相似文献
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研究了q-形变的非简谐振子的广义相干态的高阶压缩效应,给出了出现高阶压缩现象的条件. 相似文献