共查询到17条相似文献,搜索用时 203 毫秒
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本文引进二能级原子体系能够的产生二项式分布的二项式态,讨论了它的产生及其压缩、反聚束和亚泊松统计特性,在一定的极限下,二项式态趋于Glauber相干态,此时二项式分布也趋于泊松分布。这一极限使体系的一切非经典效应消失。同时采用Bloch矢量模型讨论了单原子一般二项式态的量子特性。最后把原子体系的二项式态与玻色子体系的二项式态作了比较,并指出二能级原子体系中并不能产生玻色子二项式态。
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相干态是最接近经典态的量子态,而广泛研究的相干迭加态——如奇偶相干态、Schleich的镜像迭加相干态等——则显示更多非经典效应。另外,双模及多模迭加态,特别是所谓的纠缠态,在量子信息处理如量子隐形传态和量子密码术中扮演重要角色。我们就相空间中相互垂直的相干态的迭加态进行讨论,研究其非经典特性,如光子数统计分布、正交分量压缩效应、Wigner分布函数的负性以及由此引入的非经典判别子。结果表明,这一类相干迭加态在满足某种条件下具有亚泊松光子统计分布和正交分量的压缩效应,并且参数变量在一定范围内这两种非经典效应同时存在;这些迭加态的Wigner分布中存在不同程度的负值区域.并与奇偶相干态做出了比较.计算相廊的Wigner函数积分判别子可以定最地分析其负性的深度。 相似文献
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研究了对相干态(paircoherentstate)与两个二能级原子的相互作用过程中原子和场的动力学特性,并讨论了原子间的偶极相互作用对它们的影响.结果表明:辐射场的压缩以及和压缩(sumsqueezing)的幅度,出现的次数均随原子间的耦合强度的增加而迅速减小.当两个模之间的光子数差增大时,辐射场的压缩以及和压缩的幅度,出现的次数均随之减小,辐射场的两模之间的非经典相关程度减弱,模1的亚泊松分布减弱.在原子的崩溃区域,模2的亚泊松分布增强.增大q将加快原子和双模光场的能量交换.
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将拉盖尔多项式算符作用在相干态上,构造了拉盖尔多项式算符激发相干态.利用有序算符积分技术,导出了它的归一化系数以及〈a^la^+m〉的计算表达式.采用数值计算方法,讨论了相干态相位角和平均光子数对它的非经典性质的影响.研究结果表明:一阶拉盖尔多项式算符激发相干态呈现出压缩效应、反聚束效应、亚泊松分布和Wigner函数负性等量子特性,并且相干态的相位角对它的量子特性有重要影响;另一方面,随相干态平均光子数增大,它的反聚束效应和亚泊松分布性质逐渐减弱,压缩效应和Wigner函数的负性却先增强,而后又逐渐减弱. 相似文献
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利用分束器通过条件测量制备非经典光场态和量子纠缠态 总被引:3,自引:0,他引:3
把相干态和单粒子数态作为分束器的输入态,通过条件测量可以剪去输入相干态中的任意粒子数态,并研究了这些被剪切了的光场态的性质。结果显示剪去真空态和单粒子数态的输出态具有较强的压缩和亚泊松分布等非经典效应。把剪切了的输出态和真空态输入分束器,得到的输出态具有量子纠缠性质,从而制备出量子纠缠态,同时也验证了被剪切的输出态的非经典性。 相似文献
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本文利用推广的Jaynes-Cummings模型描述N个二能级原子的超辐射,得到了辐射场的二阶关联函数的一般表达式。并进而用于缓变耦合情况,着重研究了共振情况下由超泊松光场演化成亚泊松光场的初始条件。作为例子,讨论了推广相干态及压缩相干态的演化条件。最后提出了利用相干态光场观察亚泊松光子统计的实验建议。 相似文献
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缺少一个数态的相干态 总被引:3,自引:1,他引:2
引入一种新的量子光场态/a,m〉,它是是由相干态/a/〉去掉一个数态/m〉后经归一化得到,研究了m顺次取不同值时态/a,m〉的各种量子统计性质,这相当于用一根探针在相干态内部顺次扫描数态观察各不同数态在决定相干态性质上所起的作用由此得到了一些很有意义的结果,其中特别是我们发现了这样一量子光场态--它们表明反群聚与后松分布这两种非经典光即使在单模情况下也只是基本等价而不是完全等价。 相似文献
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增加光子位移福克态的量子统计性质 总被引:2,自引:0,他引:2
引入了增加光子位移福克态 a+m| α,n〉,其中 | α,n〉是位移福克态,m是整数.用数值计算的方法研究了这种态的量子统计性质.结果表明,在位移福克态上增加光子后可以使原有的光场呈现较强的压缩,并能使光场的亚泊松特性得到明显增强. 相似文献
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X.-G. Wang S.-H. Pan G.-Z. Yang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(3):415-422
We study the nonclassical properties and algebraic characteristics of the negative binomial states introduced by Barnett recently.
The ladder operator formalism and displacement operator formalism of the negative binomial states are found and the algebra
involved turns out to be the SU(1,1) Lie algebra via the generalized Holstein-Primarkoff realization. These states are essentially Perelomov's SU(1,1) coherent states. We reveal their connection with the geometric states and find that they are excited geometric states.
As intermediate states, they interpolate between the number states and geometric states. We also point out that they can be
recognized as the nonlinear coherent states. Their nonclassical properties, such as sub-Poissonian distribution and squeezing
effect are discussed. The quasiprobability distributions in phase space, namely the Q and Wigner functions, are studied in detail. We also propose two methods of generation of the negative binomial states. d
32.80.Pj Optical cooling of atoms; trapping
Received 8 May 1999 and Received in final form 8 November 1999 相似文献
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Armando Perez-Leija Hector Moya-Cessa Omar Aguilar-Loreto 《Optics Communications》2011,284(7):1833-1836
We show that light evolution occurring in waveguide arrays with a particular n-functional square root dependence of coupling coefficients can be used to produce classical analogues of nonlinear quantum coherent states. Using operator algebras we obtain closed-form expressions describing the optical field dynamics in such structures. In addition, by numerically monitoring the Mandel's parameter, we obtain the conditions necessary to generate sub-Poissonian and super-Poissonian classical intensity distributions in the proposed photonic lattices. 相似文献
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Amit Verma 《Physics letters. A》2009,373(16):1421-1428
Recently we have shown that the reduction of the Carruthers-Nieto symmetric quantum phase fluctuation parameter (U) with respect to its coherent state value corresponds to an antibunched state, but the converse is not true. Consequently reduction of U is a stronger criterion of nonclassicality than the lowest order antibunching. Here we have studied the possibilities of reduction of U in intermediate states by using the Barnett-Pegg formalism. We have shown that the reduction of phase fluctuation parameter U can be seen in different intermediate states, such as binomial state, generalized binomial state, hypergeometric state, negative binomial state, and photon added coherent state. It is also shown that the depth of nonclassicality can be controlled by various parameters related to intermediate states. Further, we have provided specific examples of antibunched states, for which U is greater than its Poissonian state value. 相似文献
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Priya Malpani Nasir Alam Kishore Thapliyal Anirban Pathak Venkatakrishnan Narayanan Subhashish Banerjee 《Annalen der Physik》2020,532(1):1900337
The effect of two quantum state engineering processes that can be used to burn a hole at vacuum in the photon number distribution of quantum states of radiation field is compared using various witnesses of lower- and higher-order nonclassicality as well as a measure of nonclassicality. Specifically, the modification in nonclassical properties due to vacuum state filtration and a single photon addition on an even coherent state, binomial state, and Kerr state are investigated using the criteria of lower- and higher-order antibunching, squeezing, and sub-Poissonian photon statistics. Further, the amount of nonclassicality present in these engineered quantum states having enormous applications in continuous variable quantum communication is quantified and analyzed by using an linear entropy-based entanglement potential. It is observed that all the quantum states studied here are highly nonclassical, and the hole-burning processes can introduce/enhance nonclassical features. However, it is not true in general. A hole at vacuum implies a maximally nonclassical state (as far as Lee's nonclassical depth is concerned), but a particular process of hole burning at vacuum does not ensure the existence of any particular nonclassical feature. Specifically, lower- and higher-order squeezing are not observed for photon-added and vacuum filtered even coherent states. 相似文献
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S. -H. Ouyang C. -H. Lam J. Q. You 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):67-72
We study electron transport through a quantum dot, connected to non-magnetic leads, in a magnetic field. A super-Poissonian
electron noise due to the effects of both interacting localized states and dynamic channel blockade is found when the Coulomb
blockade is partially lifted. This is sharp contrast to the sub-Poissonian shot noise found in the previous studies for a
large bias voltage, where the Coulomb blockade is completely lifted. Moreover, we show that the super-Poissonian shot noise
can be suppressed by applying an electron spin resonance (ESR) driving field. For a sufficiently strong ESR driving field
strength, the super-Poissonian shot noise will change to be sub-Poissonian. 相似文献
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Zhen Wang Heng-Mei Li Hong-Chun Yuan Zhi-Long Wan Xiang-Guo Meng 《International Journal of Theoretical Physics》2017,56(3):729-740
The nonclassical and non-Gaussian quantum states—photon-added two-mode squeezed coherent states have been theoretically introduced by adding multiple photons to each mode of the two-mode squeezed coherent states. Starting from the new expression of two-mode squeezing operator in entangled states representation, the normalization factor is obtained, which is directly related to bivariate Hermite polynomials. The sub-Poissonian photon statistics, cross-correlation between two modes, partial negative Wigner function are observed, which fully reflect the nonclassicality of the target states. The negative Wigner function often display non-Gaussian distribution meanwhile. The investigations may provide experimentalists with some better references in quantum engineering. 相似文献