共查询到19条相似文献,搜索用时 62 毫秒
1.
在理论和实验上研究了光学参量振荡中产生的弱压缩真空场的光子统计行为. 弱压缩真空具有强烈的光子聚束效应,这种比热光场更强的聚束效应在量子光学和量子测量中具有重要的应用. 利用远离阈值的光学参量振荡(optical parametric oscillator, OPO )过程,在实验上产生了该弱压缩真空输出,运转波长在铯原子线附近. 通过Hanbury-Brown-Twiss(HBT)测量了OPO输出光场的二阶关联函数,实验结果与理论分析基本一致.
关键词:
压缩真空态
二阶相干度
光学参量振荡 相似文献
2.
3.
压缩态光场是量子光学研究中的一种重要量子资源.在量子信息应用中,压缩态光场的频谱带宽是限制信息传输容量的重要指标.目前,光学参量振荡器是产生强压缩度非经典光场最有效的方法之一.本文通过分析输出耦合镜透射率、线宽、阈值功率对简并光学参量振荡器频谱带宽的影响,实验完成了低阈值(18 mW)、宽频带(84.2 MHz)、高稳定(锁定基线标准偏差为0.32 MHz)量子压缩器的设计.结果表明,相比单共振光学参量振荡器,双共振腔型具有低阈值、高稳定的特点,更适合于宽频带压缩态光场的制备与实际应用. 相似文献
4.
5.
本文构造了以奇偶q相干态为特例的一般叠加q相干态|α,θ〉q=c(|α〉q+e^iθ|-α〉a),并研究了它的振幅M次方压缩性质,发现这种叠加态只存在振幅奇数次方压缩效应。并数值计算了叠加系娄籴形参数对压缩的影响。 相似文献
6.
奇偶相干迭加态的振幅高次方压缩 总被引:1,自引:0,他引:1
本文引入了学子消灭算符四次方算符α^4新的正交归一本征态:奇偶相干态和奇偶相干迭加态,并研究了奇偶相干迭加态的振幅高次方压缩特性。 相似文献
7.
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
8.
9.
利用热场动力学的方法研究了具有热噪声的相干态和压缩态中场正交分量的高阶涨落和高阶压缩.利用测量相位算符讨论了这些热化态中相位的高阶涨落.从而得到在有限温度下这些态的低阶及高阶涨落与温度的关系和压缩特性与温度的关系.由于实际的场态总是在一有限的温度下,所以讨论温度对涨落和压缩的影响是很有意义的.
关键词: 相似文献
10.
11.
This paper presents a realistic scheme for the teleportation of
coherent states in which a two-mode squeezed vacuum state serves as
the quantum channel and the position-sum and momentum-difference of
two local modes serve as the measuring observables. The average
fidelity of the teleportation of coherent states is derived for
finite squeezing parameters and it turns out that fidelity greater
than 1/2 cannot be achieved by using a classical channel alone and
the probability distribution of the measurement result is a Gaussian
distribution around the unknown parameter of the input coherent
state with a width given by the squeezing parameter. 相似文献
12.
From the normally ordered form of the density operator of a squeezed coherent state(SCS),we directly derive the compact expression of the SCS’s photon-number distribution(PND).Besides the known oscillation characteristics,we find that the PND is a periodic function with a period of π and extremely sensitive to phase.If the squeezing is strong enough,and the compound phase which is relevant to the complex squeezing and displacement parameters are assigned appropriate values,different oscillation behaviours in PND for even and odd photon numbers appear,respectively. 相似文献
13.
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
14.
The dependence of fidelity on the squeezing parameter in teleportation of the squeezed coherent states 下载免费PDF全文
This paper investigates an analytical expression of teleportation fidelity in the teleportation scheme of a single mode of electromagnetic field.The fidelity between the original squeezed coherent state and the teleported one is expressed in terms of the squeezing parameter r and the quantum channel parameter(two-mode squeezed state) p.The results of analysis show that the fidelity increases with the increase of the quantum channel parameter p,while the fidelity decreases with the increase of the squeezing parameter r of the squeezed state.Thus the coherent state(r = 0) is the best quantum signal for continuous variable quantum teleportation once the quantum channel is built. 相似文献
15.
Effects of photon addition on quantum nonlocality of squeezed entangled coherent states for Bell-inequality tests are studied theoretically. By utilizing the method of photon-parity measurement, it is found that photon addition can always increase the degrees of Bell violations within a certain parameter range. A possible scheme for generating photon-added squeezed entangled coherent states is proposed. 相似文献
16.
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
17.
Properties of field quantum entropy evolution in the Jaynes--Cummings model with initial squeezed coherent states field 下载免费PDF全文
The properties of the field quantum entropy evolution in a system of
a single-mode squeezed coherent state field interacting with a
two-level atom is studied by utilizing the complete quantum theory,
and we focus our attention on the discussion of the influences of
field squeezing parameter $\gamma $, atomic distribution angle
$\theta $ and coupling strength $g$ between the field and the atom
on the properties of the evolution of field quantum entropy. The
results obtained from numerical calculation indicate that the
amplitude of oscillation of field quantum entropy evolution
decreases with the increasing of squeezing parameter $\gamma $, and
that both atomic distribution angle $\theta $ and coupling strength
$g$ between the field and the atom can influence the periodicity of
field quantum entropy evolution. 相似文献
18.
Preparation of multicomponent motional coherent and squeezed coherent states of a trapped ion 总被引:1,自引:0,他引:1 下载免费PDF全文
In this paper, we present a scheme for preparation of multicomponent motional coherent and squeezed coherent states of the quantized centre of mass of an ion trapped in a one-dimensional harmonic potential and driven by two travelling-wave laser beams tuned to the nth red and blue vibrational sidebands, respectively. In addition, our scheme also provides experimental possibility for quantum state engineering. 相似文献
19.
We introduce quasiprobabilities based on the so-called squeezed states to represent the density operator of an oscillator. Such representations become especially useful for oscillators designed to display, strong excitation notwithstanding, pronounced quantum features such as squeezing of the quantum fluctuations of certain observables below the limit characteristic of coherent states. 相似文献