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arXiv 1807.05433quant-phphysics.comp-ph
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超越Born-Markov近似:单个量子比特的耗散动力学

Beyond the Born-Markov approximation: dissipative dynamics of a single qubit

Loris Maria Cangemi, Gianluca Passarelli, Vittorio Cataudella, Procolo Lucignano, Giulio De Filippis

摘要:

我们提出了一种基于短迭代Lanczos和精确对角化方法相结合的数值方法,适用于模拟单个量子比特与环境相互作用的约化密度矩阵的时间演化。通过选择模式离散化方法和灵活的浴态截断方案,我们能够包括在物理描述多激发过程,超越弱耦合和马尔可夫近似。我们应用我们的技术模拟三个不同的模型哈密顿量,这是相关的绝热量子计算领域。我们将我们的结果与广泛使用的Lindblad主方程的基础上获得的结果进行比较,以及与众所周知的精确和近似的方法。我们表明,我们的方法是能够恢复量子位浴系统的热力学行为,超越Born-Markov近似。最后,我们表明,即使在绝热量子退火的情况下,一个单一的量子位浴可以是有益的,在达到约化系统基态。

英文摘要:

We propose a numerical technique based on a combination of short-iterative Lanczos and exact diagonalization methods, suitable for simulating the time evolution of the reduced density matrix of a single qubit interacting with an environment. By choosing a mode discretization method and a flexible bath states truncation scheme, we are able to include in the physical description multiple-excitation processes, beyond weak coupling and Markov approximations. We apply our technique to the simulation of three different model Hamiltonians, which are relevant in the field of adiabatic quantum computation. We compare our results with those obtained on the basis of the widely used Lindblad master equation, as well as with well-known exact and approximated approaches. We show that our method is able to recover the thermodynamic behavior of the qubit-bath system, beyond the Born-Markov approximation. Finally, we show that even in the case of the adiabatic quantum annealing of a single qubit the bath can be beneficial in reaching the reduced system ground state.

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