有限温度下的量子退相干
Quantum Decoherence at Finite Temperatures
摘要：
研究了量子环境$E$存在下量子系统$S$的退相干和热化的测度。整个系统在有限温度下处于正则热态。应用微扰理论的系统环境耦合强度，我们发现，在共同的哈密顿对称性，直到一阶的耦合强度，它是足够的考虑非耦合系统预测退相干和热化措施的$S$。这种解耦允许封闭形式的表达式为微扰展开的措施，消相干和热化的自由能的$S$和$E$。耦合和解耦系统的数值结果与多达40个量子自旋验证了这些发现。
英文摘要：
We study measures of decoherence and thermalization of a quantum system $S$ in the presence of a quantum environment (bath) $E$. The whole system is prepared in a canonical thermal state at a finite temperature. Applying perturbation theory with respect to the system-environment coupling strength, we find that under common Hamiltonian symmetries, up to first order in the coupling strength it is sufficient to consider the uncoupled system to predict decoherence and thermalization measures of $S$. This decoupling allows closed form expressions for perturbative expansions for the measures of decoherence and thermalization in terms of the free energies of $S$ and of $E$. Numerical results for both coupled and decoupled systems with up to 40 quantum spins validate these findings.
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