共查询到17条相似文献,搜索用时 187 毫秒
1.
压缩态光场变耦合系数双光子J-C模型性质 总被引:12,自引:7,他引:5
讨论了初始光场为压缩态、原子-光场耦合系数随时间变化情形下双光子过程J-C模型的量子统计性质。具体研究了双光子过程中原子布居数反转、光场的压缩等随时间的演化性质,讨论了初始光场的压缩系数、压缩相位及耦合系数变化快慢对这些性质的影响。研究结果表明,初始光场的压缩系数增大,崩塌和回复的频率增大,回复值减小。当原子-光场耦合系数变化缓慢时,崩塌和回复现象被延迟。而光场逐渐失去压缩性质;而当耦合系数变化较快时,崩塌和回复现象被加速,而光场压缩量将产生振荡,压缩效应将反复出现。 相似文献
2.
研究了频率随时间变化的压缩态光场与二能级原子的相互作用,主要讨论了光场频率随时间作正弦调制和脉冲调制两种典型情况下,原子布居数反转随时间的演化特性。当光场频率随时间作正弦调制时,不仅光场频率调制,而且压缩态的压缩系数和压缩相位均对原子布居数反转的崩塌—回复过程有影响。当光场频率随时间作脉冲调制时,在原子布居数反转随时间演化过程中诱导出新的崩塌—回复过程,尤其在脉冲出现的区间内,原子布居数反转表现出持续的小幅快速振荡,这与压缩态的压缩系数无关。 相似文献
3.
研究了频率随时间变化的压缩态光场与二能级原子的相互作用,主要讨论了光场频率随时间作正弦调制和脉冲调制两种典型情况下原子布居数反转随时间的演化特性.当光场频率随时间作正弦调制时,不仅光场频率调制,而且压缩态的压缩系数和压缩相位均对原子布居数反转的崩塌-回复过程有影响.当光场频率随时间作脉冲调制时,脉冲调制的突变使各拉比振荡之间的相干性发生改变,并在原子布居数反转随时间演化过程中诱导出新的崩塌-回复过程,尤其在脉冲出现的区间内,原子布居数反转表现出持续的小幅快速振荡,这与压缩态的压缩系数无关.
关键词:
Jaynes-Cummings模型
压缩态
原子布居数反转 相似文献
4.
5.
利用全量子理论的方法,研究了存在相位退相干时多光子T-C模型中两个二能级原子与二项式光场相互作用系统中两原子的布居数反转。讨论了相位退相干系数、二项式光场系数、最大光子数、跃迁光子数对原子布居数反转的影响。结果表明:相位退相干减少了原子布居数反转的振幅、破坏了原子的量子特性。改变跃迁光子数,可以改变原子间布居数反转演化周期及演化强度。当二项式光场的最大光子数增大时,原子布居差的崩塌-回复现象就会逐渐消失。相位退相干因子不变时, 二项式光场从相干态过渡到数态过程中,原子布居的振荡频率由大变小,周期性的崩塌与回复现象逐渐消失。 相似文献
6.
利用全量子理论的方法,研究了存在相位退相干时多光子T-C模型中两个二能级原子与二项式光场相互作用系统中两原子的布居数反转。讨论了相位退相干系数、二项式光场系数、最大光子数、跃迁光子数对原子布居数反转的影响。结果表明:相位退相干减少了原子布居数反转的振幅、破坏了原子的量子特性。改变跃迁光子数,可以改变原子间布居数反转演化周期及演化强度。当二项式光场的最大光子数增大时,原子布居差的崩塌-回复现象就会逐渐消失。相位退相干因子不变时, 二项式光场从相干态过渡到数态过程中,原子布居的振荡频率由大变小,周期性的崩塌与回复现象逐渐消失。 相似文献
7.
存在内禀退相干时二项式光场中原子的布居数反转 总被引:1,自引:1,他引:0
在Milburn内禀退相干模型下,研究了二项式光场与二能级原子相互作用系统中原子的布居数反转,分析了内禀退相干,二项式光场系数和场的最大光子数对原子布居数反转的影响.结果表明,存在内禀退相干时,原子布居数反转出现明显的崩塌-回复现象,随着时间的演化,Rabi振荡的包络值将很快的崩塌到零,并且随着内禀退相干因子的减小,衰减加剧;当内禀退相干因子不变时,二项式光场从相干态过渡到中间态,以及由中间态到数态过程中,原子布居数反转出现明显的崩塌-回复现象,而且Rabi振荡的频率会明显加快;当二项式光场的最大光子数增大时,原子布居差的崩塌-回复现象就会逐渐消失. 相似文献
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9.
在非旋波近似下,研究了频率随时间变化的相干态光场与二能级原子的相互作用,讨论了光场频率随时间作正弦和方波变化时,原子布居数反转随时间的演化特性。数值计算结果表明,当光场频率不随时间变化时,原子布居数反转的周期随着平均光子数的增大而增大;当光场频率随时间作正弦变化时,原子布居数反转塌缩回复的周期和振幅受到了很大影响,光场频率对演化曲线的振荡频率起到了调制作用;当光场频率随时间作方波变化时,原子布居数反转塌缩回复的周期发生了改变,而且出现了新的塌缩回复现象。 相似文献
10.
研究了非旋波近似下频率随时间变化的相干态光场与二能级原子的相互作用,主要讨论了光场频率随时间作正弦和方波变化两种典型情况下,原子布居数反转随时间的演化特性. 当光场频率随时间作正弦变化时,原子布居数反转的崩塌-回复过程和由虚光子过程引起的快速振荡均会受到影响. 当光场频率随时间以方波形式变化时,脉冲调制不仅在原子布居数反转随时间演化过程中诱导出新的崩塌-回复过程,而且可以引起虚光子快速振荡的突变.
关键词:
Jaynes-Cummings模型
非旋波近似
原子布居数反转 相似文献
11.
The interactions between a two-level atom and a field via two-photon
transition without rotating wave approximation have been
investigated. We emphasize the dynamic behaviors of the atomic
population inversion, the field squeezing, and the atomic dipole
squeezing numerically when the field frequency varies with time in
the forms of sine and rectangle. Some interesting phenomena are
discovered and discussed. The good periodic character of the atomic
population inversion in the standard two-photon Jaynes--Cummings
model is weakened by the influence of the sine field frequency
modulation. The rectangular field frequency modulation can change
the correlation among different oscillations suddenly and induce new
collapse-revival processes of the atomic population inversion. The
field squeezing increases at the beginning of time, but then
decreases and loses as the time increases after it reaches the
maximum due to the sine modulation. The effects of the rectangular
modulation on the field squeezing depend mostly on the appearance
time of the modulation. The atomic dipole squeezing is weakened
under the influence of the sine or rectangular modulation. Our
results indicate that it is possible to perform the dynamic
controlling of the system properties by changing the parameters of
the system with time. This implies that one can dynamically control
a quantum information process by choosing the system modulation
properly. 相似文献
12.
压缩真空场与耦合双原子Raman相互作用系统场熵的演化特性 总被引:1,自引:1,他引:0
利用全量子理论,研究了压缩真空场与耦合双原子Raman相互作用系统的场熵演化特性,讨论了系统耦合常数和光场初始压缩因子对场熵演化特性的影响.结果表明,场熵的时间演化规律与原子布居差的时间演化规律非常相似.当原子间的偶极-偶极相互作用较弱时,场熵演化呈现周期性的崩塌与回复现象;当原子间的偶极-偶极相互作用较强时,场熵演化呈现不规则振荡,崩塌与回复周期现象消失. 相似文献
13.
利用相干态正交化展开方法,在非旋波近似下研究了原子的布居反转随时间的演化情况.数值计算的结果表明了,场频以及耦合强度不随时间变化时,布居反转的周期随着平均光子数的增加而增大,虚光子效应引起的快速振荡随耦合强度的增大而逐渐增大.当光场随时间做正弦调制时,光场的振幅α和角频率β对布居反转的演化都会产生很大影响.光场随时间做方波形式变化,会导致原子布居反转出现新的塌缩回复现象.无论是正弦调制还是方波调制,都会对由虚光子效应产生的小锯齿状的振荡产生影响.
关键词:
相干态正交化展开
非旋波近似
原子布居数反转 相似文献
14.
The entropy squeezing properties for a two-level
atom interacting with a two-mode field via two different competing transitions
are investigated from a quantum information point of view. The influences
of the initial state of the system and the relative coupling strength between the atom and the field
on the atomic information entropy squeezing are discussed. Our results show that
the squeezed direction and the frequency of the information entropy squeezing
can be controlled by choosing the phase of the atom dipole and the relative competing
strength of atom-field, respectively.
We find that, under the same condition, no atomic variance squeezing is predicted from the
HUR while optimal entropy squeezing is obtained from the EUR, so the quantum information
entropy is a remarkable precision measure for the atomic squeezing
in the considered system. 相似文献
15.
研究了存在Kerr介质时,双模压缩真空场与耦合二能级原子相互作用系统中光子的统计性质,讨论了Kerr介质与光场的耦合强度、光场的初始压缩因子和原子的初态对光子统计性质的影响.数值计算结果表明,光子周期性地交替呈现聚束和反聚束效应,光场两模之间总是呈现正相关,并且这种相关为非经典相关;Kerr介质的影响使光场的二阶相干度演化曲线呈现周期性的崩塌-回复现象,随着Kerr效应的加强,崩塌-回复周期变短,以至消失.
关键词:
Kerr介质
耦合双原子
双模压缩真空场
光子统计性质 相似文献
16.
Based on the time-convolutionless master-equation approach, we investigate the squeezing dynamics of two atoms in dissipative cavities. We find that the atomic squeezing is related to initial atomic states, atom–cavity couplings, nonMarkovian effects and resonant frequencies of an atom and its cavity. The results show that a collapse–revival phenomenon will occur in the atomic squeezing and this process is accompanied by the buildup and decay of entanglement between two atoms. Enhancing the atom–cavity coupling can increase the frequency of the collapse–revival of the atomic squeezing.The stronger the non-Markovian effect is, the more obvious the collapse–revival phenomenon is. In particular, if the atom–cavity coupling or the non-Markovian effect is very strong, the atomic squeezing will tend to a stably periodic oscillation in a long time. The oscillatory frequency of the atomic squeezing is dependent on the resonant frequency of the atom and its cavity. 相似文献
17.
In this paper we present a general theoretical model for the interaction between a number of two-level atoms constituting Bose-Einstein condensate (BEC) and a single-mode quantized field. In addition to the usual interacting terms, we take into account interatom as well as higher-order atom-field interactions. To simplify the Hamiltonian of system, after using the Bogoliubov approximation we proceed to calculate the transformed operators of atoms and field. Then, to quantify the spontaneous emission, we get analytical expressions for the expectation value of ?z as the atomic population inversion (API), in the cases of number and coherent states for the atomic subsystem. Our results show that the above-mentioned model interaction leads to the appearance of collapse-revival phenomenon in API. In more detail, the revival time may be tuned by adjusting the interatom interaction constant. Also, the damping process lowers the amplitude of API, but does not change the CR times for weak damping. Moreover, increasing the damping may decrease the number of CRs in a given interval of time such that no revival occurs. Briefly, it may be concluded that in the resonant case the revival times are insensitive to the change of the higher-order atom-field interaction constant and are affected only by the interatom interactions. Finally, we express that, how we can find a practical procedure to measure the quantum states of atoms in BEC. 相似文献