共查询到19条相似文献,搜索用时 93 毫秒
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考虑具有强度耦合的广义Jaynes-Cummings模型与压缩真空相互作用。根据Pegg和Bamett新的相位理论,不仅得到了压缩真空场的相位分布,相位期待值和相位涨落的普遍表示式,及其演化图示,而且还导出了弱压缩真空和强压缩真空情形的近似角极表示式。对于压缩真空的压缩量与相位特性之间的关系进行了简要讨论。 相似文献
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应用Pegg和Barnett提出的相位算符和相位态理论,研究了激发压缩真空态的相位概率分布特性.数值计算结果表明,激发压缩真空态的相位概率分布主要受到相位参量和压缩参量的调节,相位参量使相位概率分布呈峰值结构,压缩参量的变化将影响相位概率分布的峰值强度,此外激发光子数对相位概率分布也有较大的影响. 相似文献
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压缩光透过克尔介质时光场的相位和压缩特性及其关联 总被引:1,自引:0,他引:1
用Pegg-Barnett理论研究了压缩真空态光与克尔介质的相互作用对光场相位特性的影响,讨论了光场的压缩和高阶压缩与相位特性之间的关联.光场相位正交分量的各阶矩呈现周期性的振荡,与相位分布函数密切相关. 相似文献
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研究了强度差测量方案下,探测器量子效率对光子数态、关联数态、压缩真空态三种量子光源注入的马赫-曾德尔干涉仪相位测量灵敏度的影响.获得了相位测量灵敏度与效率的定量关系,比较了探测效率对不同量子态注入的干涉仪相位灵敏度的影响.研究表明:光子数态注入时,相位测量灵敏度始终不能超越标准量子极限;关联数态注入时,无论多大的光子数,要获得相位测量的量子增强,探测效率不得小于75%;对于压缩真空态,只要有压缩存在就可以获得一定的相位测量的量子增强;关联数态、压缩真空态的注入,相位灵敏度皆随探测效率的增大而不同程度的提高,且压缩真空态比关联数态具有更好的量子增强效果.给出了在量子增强的精密测量实验中对探测效率的要求,并结合实际应用说明了探测效率的提高有助于提高干涉仪探测的灵敏度. 相似文献
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两模在单双模组合压缩真空态中同等程度地被压缩 总被引:2,自引:2,他引:0
从SG相位算符的正规编序形式出发,我们得到了双模的SG相位算符在单双模组合压缩真空态中无相位差.这说明,在单-双模组合压缩真空态中两模同等程度地被压缩.这对探索新的压缩机制具有一定的启发作用. 相似文献
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《物理学报》2016,(19)
针对文献[物理学报65 054203]中量子零拍探测技术测量的输出相位精度与相位自身相关,且对本振光、压缩真空光和相干光的相位有严格要求,在理论上设计了一种相干态和压缩真空态的自适应最优估计方法.首先以纯态的方法推导得到相干态和压缩真空态的量子费舍尔信息,sinh~2r+|α|~2e~(2r).设计了一组能使估计误差达到量子Cramer-Rao下界的最优半正定算子值测量算子,但该测量算子需要精确已知所要估计的相位参数.为此,引入了一种自适应估计方法,通过不断更新测量算子和概率函数,利用最大似然估计器逐渐得到相位参数.经理论证明,该方法能以概率1收敛于相位真值,且能达到量子Cramer-Rao下界. 相似文献
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Critical slowing down effect in a bistable model of a two-level atomic medium in a ring cavity and in contact with squeezed vacuum field is examined within the mean field approximations in the high-, low- and arbitrary-Q cavity cases. Depending on the squeezed vacuum field phase parameter, the time response to linear perturbation of the incident field near the swtiching-on point can be enhanced or reduced compared with the normal vacuum case. In the low-Q cavity case with atomic collisional broadening switching time is both increased and become insensitive to the phase of the squeezed vacuum field. Analytical expressions are given and analysed for the critical (extermal) values of the incident field. In the high-Q cavity, Gaussian field feature causes lesser-steep transition between the stable states in both the normal and squeezed vacuum cases.Received: 25 April 2004, Published online: 24 August 2004PACS:
42.65.Pc Optical bistability, multistability, and switching, including local field effects - 42.65.-k Nonlinear optics 相似文献
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Optical enhanced interferometry with two-mode squeezed twin-Fock states and parity detection
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We theoretically investigate the quantum enhanced metrology using two-mode squeezed twin-Fock states and parity detection. Our results indicate that, for a given initial squeezing parameter, compared with the two-mode squeezed vacuum state, both phase sensitivity and resolution can be enhanced when the two-mode squeezed twin-Fock state is considered as an input state of a Mach–Zehnder interferometer. Within a constraint on the total photon number, although the two-mode squeezed vacuum state gives the better phase sensitivity when the phase shift φ to be estimated approaches to zero, the phase sensitivity offered by these non-Gaussian entangled Gaussian states is relatively stable with respect to the phase shift itself. When the phase shift slightly deviates from φ= 0, the phase sensitivity can be still enhanced by the two-mode squeezed twin-Fock state over a broad range of the total mean photon number where the phase uncertainty is still below the quantum standard noise limit. Finally, we numerically prove that the quantum Cramer–Rao bound can be approached with the parity detection. 相似文献
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Phase estimation of phase shifts in two arms for an SU(1,1) interferometer with coherent and squeezed vacuum states
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We theoretically study the quantum Fisher information(QFI) of the SU(1,1) interferometer with phase shifts in two arms by coherent ? squeezed vacuum state input, and give the comparison with the result of phase shift only in one arm.Different from the traditional Mach–Zehnder interferometer, the QFI of single-arm case for an SU(1,1) interferometer can be slightly higher or lower than that of two-arm case, which depends on the intensities of the two arms of the interferometer.For coherent ? squeezed vacuum state input with a fixed mean photon number, the optimal sensitivity is achieved with a squeezed vacuum input in one mode and the vacuum input in the other. 相似文献
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In this paper,we investigate the phase sensitivities in two-path optical interferometry with asymmetric beam splitters.Here,we present the optimal conditions for the transmission ratio and the phase of the beam splitter to gain the highest sensitivities for a general class of non-classical states with parity symmetry.Additionally,we address the controversial question of whether the scheme with a combination of coherent state and photon-added or photon-subtracted squeezed vacuum state is better or worse than the most celebrated one using a combination of coherent state and squeezed vacuum state. 相似文献
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利用量子技术增强Sagnac效应提高陀螺输出精度具有重要的研究意义, 是实现全自主导航的重要途径. 以相干态激光作为输入光源的光学陀螺因真空零点波动使其输出精度限制于散粒噪声极限而难以提高. 为减小真空波动的影响, 提出在激光输入的分束器的另一输入端输入压缩真空光并结合平衡零拍探测技术的方法增强Sagnac效应. 理论分析表明Sagnac效应性能得到有效提升: 干涉输出的灵敏度检测极限和动态范围均随着压缩程度的增加而呈指数级增长. 该方法只需对经典光学陀螺做少量改动就可实现, 是提高光学陀螺输出精度的一种新方法. 相似文献
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Xiao-Yu Hu 《Frontiers of Physics》2016,11(3):114203
We study the phase sensitivity of an SU(1,1) interferometer with two input beams in the displaced squeezed vacuum state and the coherent state, respectively. We find that there exists an optimal squeezing fraction of the displaced squeezed vacuum state that optimizes the phase sensitivity. We also examine the effects of some factors, including the loss, mean photon number of the input beams and amplitude gain of the optical parameter amplifiers, on the optimal squeezing fraction so that we can choose the optimal values to enhance the phase sensitivity. 相似文献
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Z.-C. Wang Z.-Y. Chen Y. Xu 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(2):185-190
A theoretical study is made of the steady-state populations of a three-level atom in a ladder configuration, driven by a superposition
of a monochromatic laser wave with a broad-band squeezed vacuum. The master equation for the system and the atomic Bloch equations
are derived. The steady-state populations are calculated numerically and shown graphically as functions of two-photon detuning
for various cases of the squeezed vacuum. It is shown that, the atomic populations depend strongly on the relative phase of
the driving field and the squeezed vacuum. When the phase matching condition is fulfilled, there will be a strong two-photon
resonant absorption from the squeezed vacuum, a characteristic different from absorption of photons from a classical field.
Received: 28 May 1997 / Revised and Accepted: 10 December 1997 相似文献
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应用Pegg-Barnett位相理论,研究了Jaynes-Cummings模型(J-C模型)中压缩真空初态场位相演化特性,具体计算了弱压缩条件下,场的位相几率分布函数及位相涨落,给出了在极坐标中位相几率分布演化曲线,讨论了原子与场相互作用对场的位相性质的影响。 相似文献