Quantum-phase and information-entropy dynamics of a molecular system interacting with a two-mode squeezed coherent field
Quantum-phase and information-entropy dynamics of a molecular system interacting with a two-mode squeezed coherent field
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与二模压缩相干场相互作用的分子系统的量子相和信息熵动力学
DOI：
10.1103/physreva.64.033415
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发表时间：
2001
影响因子：
2.9
通讯作者：
K. Yamaguchi
中科院分区：
文献类型：
--
作者：
M. Nakano;K. Yamaguchi
研究了一个分子态模型系统与一个双模压缩相干场相互作用的量子动力学，其中每个模都是初始关联的。作为一个例子，我们考虑了一个三态分子模型，它模拟了反式辛四烯的电子激发态，通过使用Pariser-Parr-Pople哈密顿量的全组态相互作用计算得到，与双模压缩相干场相互作用。为了比较，我们还进行了平行研究，其中初始场是在不相关的双模态中制备的，即，双模相干态和双模热态。众所周知，双模相干场的情形导致Rabi振荡的通常的振荡恢复现象，而双模热态的情形导致Rabi振荡的不规则演化。虽然双模压缩相干光场与双模相干光场具有相似的双光子回复振荡行为，但双光子回复振荡的振幅和周期却有一定的差异。此外，这两个领域的基态和第二激发态之间的非对角分子密度矩阵的动力学被发现是明显不同的。这种吸引行为被发现与Pegg-Barnett相位算符和光子的初始准概率（Q函数）分布所获得的双模光子相位动力学密切相关。相位特性的这些差异也被证明会显著影响分子的信息熵的动力学，即，分子熵，表示分子和光子之间的纠缠程度。
We investigate the quantum dynamics for a molecular-state-model system interacting with a resonant two-mode squeezed coherent field, in which each mode is initially correlated. As an example, we consider a three-state molecular model, which mimics the electronic excited states of trans-octatetraene obtained by a full-configuration-interaction calculation using the Pariser-Parr-Pople Hamiltonian, interacting with a two-mode squeezed coherent field. For comparison, we also perform parallel studies, in which the initial fields are prepared in uncorrelated two-mode states, i.e., a two-mode coherent state and a two-mode thermal state. It is well known that the case of two-mode coherent field leads to the usual collapse-revival phenomena of the Rabi oscillations, while the case of a two-mode thermal state leads to an irregular evolution of them. Although the two-mode squeezed coherent field exhibits similar collapse-revival behavior to that for the two-mode coherent field, some differences are detected in the amplitudes and periods of collapse-revival oscillations. Further, the dynamics of off-diagonal molecular density matrices between the ground and second excited states for these two fields are found to be distinctively different from each other. Such attractive behavior is found to be closely associated with the two-mode photon-phase dynamics obtained by the Pegg-Barnett phase operator and the initial quasiprobability (Q function) distribution of photons. These differences in phase properties are also shown to significantly affect the dynamics of the information entropy for a molecule, i.e., molecular entropy, which represents the degree of entanglement between the molecule and photons.