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We present a utilitarian review of the family of matrix groups Sp(2n, ℛ), in a form suited to various applications both in optics and quantum mechanics. We contrast these groups and their geometry
with the much more familiar Euclidean and unitary geometries. Both the properties of finite group elements and of the Lie
algebra are studied, and special attention is paid to the so-called unitary metaplectic representation of Sp(2n, ℛ). Global decomposition theorems, interesting subgroups and their generators are described. Turning ton-mode quantum systems, we define and study their variance matrices in general states, the implications of the Heisenberg uncertainty
principles, and develop a U(n)-invariant squeezing criterion. The particular properties of Wigner distributions and Gaussian pure state wavefunctions under
Sp(2n, ℛ) action are delineated. 相似文献
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D. Rodriguez-Mendez 《Optics Communications》2011,284(13):3345-3347
We show how NOON states may be generated entangling two cavities by passing atoms through them. The atoms interact with each cavity via two-photon resonant transitions. We take advantage of the fact that depending on the state the atom enter (excite or ground), it leaves or takes two photons per interaction and leaves the cavities in a pure state. 相似文献
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Higher-order squeezing of quantum electromagnetic fields and higher-order uncertainty relations in two-mode squeezed states
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It is found that the two-mode output quantum electromagnetic field in two-mode squeezed states exhibits higherorder squeezing to all even orders, and the degree of higher-order squeezing is greater than that of the second-order.The higher-order squeezed parameter and squeezed limit due to the modulation frequency are investigated. The smaller the modulation frequency is, the stronger the degree of higher-order squeezing becomes. Furthermore, the higher-order uncertainty relations in two-mode squeezed states are presented for the first time. The product of higher-order noise moments is related to even order number N and the squeeze factor r. 相似文献
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Devendra Kumar Mishra 《Optics Communications》2010,283(17):3284-3290
Recently, Prakash and Mishra [J. Phys. B: at. Mol. Opt. Phys., 39, 2291(2006); 40, 2531(2007)] have studied higher order sub-Poissonian photon statistic conditions for non-classicality in the form of general inequalities for expectation values of products of arbitrary powers of photon number and of photon-number fluctuation. It is, therefore, vital to study the generation of these higher order sub-Poissonian photon statistics (phase-insensitive behavior) in a physically realizable medium and their relations to higher order squeezing (phase-sensitive behavior). In the present paper, we study higher order non-classical properties, such as Hong and Mandel squeezing, amplitude-squared squeezing and higher order sub-Poissonian photon statistics, of squeezed Kerr state which is generated by squeezing the output of a Kerr medium whose input is coherent light. Such states can be realized if laser light is sent through an optical fiber and then into a degenerate parametric amplifier. It is established that the squeezed Kerr state can exhibit higher order non-classical properties. 相似文献
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Squeezed states are one of the most useful quantum optical models having various applications in different areas, especially in quantum information processing. Generalized squeezed states are even more interesting since, sometimes, they provide additional degrees of freedom in the system. However, they are very difficult to construct and, therefore, people explore such states for individual setting and, thus, a generic analytical expression for generalized squeezed states is yet inadequate in the literature. In this article, we propose a method for the generalization of such states, which can be utilized to construct the squeezed states for any kind of quantum models. Our protocol works accurately for the case of the trigonometric Rosen–Morse potential, which we have considered as an example. Presumably, the scheme should also work for any other quantum mechanical model. In order to verify our results, we have studied the nonclassicality of the given system using several standard mechanisms. Among them, the Wigner function turns out to be the most challenging from the computational point of view. We, thus, also explore a generalization of the Wigner function and indicate how to compute it for a general system like the trigonometric Rosen–Morse potential with a reduced computation time. 相似文献
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O. Abbasi 《Optics Communications》2010,283(12):2566-2574
Nonlinear coherent states (CSs) and their dual families were introduced recently. In this paper, we want to obtain their superposition and investigate their non-classical properties such as antibunching effect, quadrature squeezing and amplitude squared squeezing. For this purpose two types of superposition are considered. In the first type, we neglect the normalization factors of the two components of the dual pair, superpose them and then we normalize the obtained states, while in the second type we superpose the two normalized components and then again normalize the resultant states. As a physical realization, the formalism will then be applied to a special physical system with known nonlinearity function, i.e., Hydrogen-like spectrum. We continue with the (first type of) superposition of the dual pair of Gazeau-Klauder coherent states (GKCSs) as temporally stable CSs. An application of the proposal will be given by employing the Pöschl-Teller potential system. The numerical results are presented and discussed in detail, showing the effects of this special quantum interference. 相似文献
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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
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We show that stochastic electrodynamics and quantum mechanics give quantitatively different predictions for the quantum nondemolition (QND) correlations in travelling wave second harmonic generation. Using phase space methods and stochastic integration, we calculate correlations in both the positive-P and truncated Wigner representations, the latter being equivalent to the semi-classical theory of stochastic electrodynamics. We show that the semi-classical results are different in the regions where the system performs best in relation to the QND criteria, and that they significantly overestimate the performance in these regions. 相似文献
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低频压缩态光场可用于提高引力波探测器灵敏度, 近年来受到人们的广泛关注. 相对于高频段而言, 低频压缩态的产生更容易受到外界环境噪声的干扰而不易被观察到. 本文采用全固化单频倍频Nd: YVO4/KTP激光器作为光源, 利用双波长共振的光学参量振荡器实现参量过程, 以1064 nm波长的红外作为基频光, 激光器腔内倍频产生的532 nm绿光作为抽运光, 通过调节周期性极化磷酸氧钛钾晶体温度使光学参量振荡器达到双波长同时共振, 采用真空注入的方式, 利用Pound-Drever-Hall锁腔技术锁定抽运场. 输出压缩光通过平衡零拍探测, 最终在实验上获得了频率低至3 kHz的真空压缩, 所直接观察到的压缩度为2 dB. 相似文献
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Arun Kumar Pati 《Pramana》2002,59(2):221-228
Entangling an unknown qubit with one type of reference state is generally impossible. However, entangling an unknown qubit
with two types of reference states is possible. To achieve this, we introduce a new class of states called zero sum amplitude (ZSA) multipartite, pure entangled states for qubits and study their salient features. Using shared-ZSA states, local operations
and classical communication, we give a protocol for creating multipartite entangled states of an unknown quantum state with
two types of reference states at remote places. This provides a way of encoding an unknown pure qubit state into a multiqubit
entangled state. 相似文献
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构造出了一种新的奇偶非线性相干态, 并借助于数值计算方法研究了它们的压缩、振幅平方压缩、反聚束和相位概率分布等非经典性质. 结果表明, 与通常的奇偶相干态和非线性奇偶相干态不同, 在参数|λ|的不同取值范围内, 新的奇偶非线性相干态在Y1和Y2两个方向均可呈现振幅平方压缩效应, 而压缩效应仅在偶非线性相干态的X2方向上呈现, 反聚束效应仅在奇非线性相干态中呈现. 另外, 通过研究新的奇偶非线性相干态相位概率分布, 发现新的奇偶非线性相干态具有完全不同的量子干涉特性.
关键词:
新的奇偶非线性相干态
压缩效应
反聚束
相位概率分布 相似文献
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Photon-added and photon-subtracted displaced Fock states and their non-classical properties
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A new kind of quantum optical state, photon-added and
-subtracted displaced Fock states, is introduced by applying the
inverse of bosonic creation and annihilation operators to
displaced Fock states. The quantum statistical properties of these
states are investigated by numerical methods. Numerical results
indicate that these states reveal some interesting non-classical
properties, such as anti-bunching effects, sub-Poisson
distributions and negativities of their Wigner
functions. 相似文献
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We study the spin squeezing property of weighted graph states,which can be used to improve sensitivity in interferometry.We study the time evolution of spin squeezing under local decoherence acting independently on each qubit.Based on the analysis,the spin squeezing of the weighted graph states is somehow robust in the presence of decoherence and the decoherence limit in the improvement of the interferometric sensitivity is still achievable.Furthermore,one can obtain the optimal improvement of sensitivity by tuning the weighted of each edges of the weighted graph state. 相似文献
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运用求解Schrdinger方程和数值计算方法,研究了处于Bell态的两个全同二能级纠缠原子与双模纠缠相干光场相互作用系统的光场压缩特性,分析了双模纠缠相干光场的纠缠程度、双模纠缠相干光场的初始平均光子数对光场压缩性质的影响,以及两纠缠原子的相互作用强度对光场压缩性质的影响.结果表明:若初始时刻原子处在Bell态|β11〉,则不出现光场的压缩效应,而处在另外三种Bell态时,在一定的条件下均可呈现光场的压缩效应.光场压缩效应不仅与初始光场的平均光子数以及原子的初态有关而且与双模纠缠相干光场的纠缠程度有关,但与两纠缠原子的相互作用强度的大小没有明显的关系. 相似文献
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By numerical diagonalization of honeycomb-lattice tight-binding Hamiltonian we calculate the density of state (DOS) of irregularly shaped graphene quantum dots fabricated in the form of graphene nano-flakes. The finite-size electron confinement and the edge states result in the central peak of DOS that is located at the zero-energy Dirac point. The amplitude and width of the peak are provided by the form of the graphene cluster, but no regular correlation with its shape was found. 相似文献