[论文解读] Cavity Quantum Electrodynamics of Multipartite Systems

Moslem Alidoosty Shahraki, Sina Khorasani|arXiv (Cornell University)|Nov 4, 2012

Quantum Information and Cryptography参考文献 53被引用 1

一句话总结

本文针对具有任意数量发射体和腔模的多体系统，提出了腔量子电动力学的数值精确解，完整包含场-偶极子和偶极子-偶极子相互作用，无任何近似。结果表明，超强耦合会诱导混沌动力学和突变相变——与弱耦合和强耦合区域截然不同——并借助自定义的高精度代码，实现了对自旋纠缠实验的高精度模拟。

ABSTRACT

Cavity quantum electrodynamics of multipartite systems is studied in depth, which consist of an arbitrary number of emitters in interaction with an arbitrary number of cavity modes. The governing model is obtained by taking the full field-dipole and dipole-dipole interactions into account, and is solved in the Schrodinger picture without assumption of any further approximation. An extensive code is developed which is able to accurately solve the system and track its evolution with high precision in time, while maintaining sufficient degrees of arbitrariness in setting up the initial conditions and interacting partitions. Using this code, we have been able to numerically evaluate various parameters such as probabilities, expectation values (of field and atomic operators), as well as the concurrence as the most rigorously defined measure of entanglement of quantum systems. We present and discuss several examples including a seven-partition system consisting of six quantum dots interacting with one cavity mode. We observe for the first time that the behavior of quantum systems under ultrastrong coupling is significantly different than the weakly and strongly coupled systems, marked by onset of a chaos and abrupt phase changes. We also discuss how to implement spin into the theoretical picture and thus successfully simulate a recently reported spin-entanglement experiment.

研究动机与目标

• 开发一个适用于任意数量发射体和腔模的腔量子电动力学的完全非微扰框架。
• 在无近似的情况下建模完整的场-偶极子和偶极子-偶极子相互作用，确保动力学的高精度。
• 模拟超强耦合区域中的复杂量子现象，如纠缠和相变。
• 通过将自旋自由度整合到理论框架中，实现对近期自旋纠缠实验的精确建模。

提出的方法

• 开发了一种在薛定谔绘景下运行的数值求解器，精确求解完整哈密顿量，无进一步近似。
• 该方法保持初始条件和相互作用子系统划分的完全任意性。
• 以高精度追踪时间演化，计算概率、场算符和原子算符的期望值，以及作为纠缠度量的concurrence。
• 该代码支持发射体和腔模的任意配置，可模拟复杂系统，如六量子点一模系统。
• 将自旋自由度整合到模型中，以模拟自旋纠缠实验。
• 严格计算concurrence，以量化不同耦合区域下的纠缠程度。

实验结果

研究问题

• RQ1 与弱耦合和强耦合区域相比，多体腔QED系统在超强耦合下的动力学行为如何？
• RQ2 在超强耦合系统中，量子混沌和突变相变的特征信号是什么？
• RQ3 能否在无微扰近似的情况下精确模拟完整的偶极子-偶极子和场-偶极子相互作用？
• RQ4 如何一致地将自旋自由度整合到理论框架中，以模拟近期报道的自旋纠缠实验？
• RQ5 通过concurrence量化的纠缠，在表征不同耦合区域之间的转变中起什么作用？

主要发现

• 超强耦合诱导混沌动力学和突变相变，使其与弱耦合和强耦合区域的行为显著不同。
• 系统表现出非平凡的纠缠演化，concurrence作为量子关联的可靠度量。
• 数值代码成功以高精度模拟了六个量子点耦合单个腔模的七子系统。
• 自旋自由度成功整合到模型中，实现了对近期报道的自旋纠缠实验的精确模拟。
• 完整哈密顿量（包括所有偶极子相互作用）被精确求解，无任何近似，揭示了此前未观测到的动力学特征。