Real-time density-matrix coupled-cluster approach for closed and open systems at finite temperature.
Real-time density-matrix coupled-cluster approach for closed and open systems at finite temperature.
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DOI：
10.1063/1.5121749
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
Philip Shushkov;Thomas F. Miller
中科院分区：
文献类型：
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作者：
Philip Shushkov;Thomas F. Miller
我们利用热场形式将耦合簇方法推广到有限温度下封闭和开放系统的相关量子动力学。该方法以指数形式表示随时间变化的密度矩阵，并描述沿Keldysh路径轮廓的时间演化。该方法的一个明显优点是作为时间的函数精确地保存痕迹，确保了概率和粒子数的守恒。此外，该方法避免了相关胸罩状态的计算，简化了计算实现。我们在热准粒子表示中开发了该方法，该方法允许与传统耦合簇形式的投影方法和图解技术无缝连接。为了比较，我们还将热场框架应用于密度-矩阵重整化-群方法，以获得有限温度下封闭和开放系统的参考结果。我们在单杂质Anderson模型的相关电子动力学上测试了密度-矩阵耦合簇方法的单次和双次近似，证明了新方法成功地捕获了有限温度下封闭系统和驱动耗散开放系统的相关动力学。这一令人鼓舞的性能激发了非平衡量子多体动力学在现实系统中的未来应用。
We extend the coupled-cluster method to correlated quantum dynamics of both closed and open systems at finite temperatures using the thermofield formalism. The approach expresses the time-dependent density matrix in an exponential ansatz and describes time-evolution along the Keldysh path contour. A distinct advantage of the approach is exact trace-preservation as a function of time, ensuring conservation of probability and particle number. Furthermore, the method avoids the computation of correlated bra-states, simplifying the computational implementation. We develop the method in a thermal quasiparticle representation, which allows seamless connection to the projection method and diagrammatic techniques of the traditional coupled-cluster formalism. For comparison, we also apply the thermofield framework to the density-matrix renormalization-group method to obtain reference results for closed and open systems at finite temperature. We test the singles and doubles approximation to the density-matrix coupled-cluster method on the correlated electronic dynamics of the single-impurity Anderson model, demonstrating that the new method successfully captures the correlated dynamics of both closed systems at finite temperature and driven-dissipative open systems. This encouraging performance motivates future applications to nonequilibrium quantum many-body dynamics in realistic systems.