论文标题
扰动图实现了单位运输效率而没有环境噪声
Perturbed graphs achieve unit transport efficiency without environmental noise
论文作者
论文摘要
激发通过网络的连贯传输对应于图上的连续时间量子步行，并且系统的传输属性可能会在图形上和初始状态根本不同。运输效率，即以某个顶点捕获的综合概率，是转移过程成功率的量度。已知纯粹相干的量子运输的效率不如观察到的激发传输，例如在生物系统中，并且有证据表明环境噪声确实对于激发运输至关重要。与此图片的不同，我们在这里纯粹在高度对称的图上解决了纯粹的连贯运输，并在分析上表明，可以提高传输效率而无需环境噪声，即仅使用图表的最小扰动。特别是，我们表明，根据初始状态是本地化的还是在两个顶点状态的叠加中增加一个或两个边缘的额外权重，可以打破图形的固有对称性，并且可能足以达到单位运输效率。我们还简要讨论了获得无效运输效率的条件，即避免捕获。
Coherent transport of an excitation through a network corresponds to continuous-time quantum walk on a graph, and the transport properties of the system may be radically different depending on the graph and on the initial state. The transport efficiency, i.e., the integrated probability of trapping at a certain vertex, is a measure of the success rate of the transfer process. Purely coherent quantum transport is known to be less efficient than the observed excitation transport, e.g., in biological systems, and there is evidence that environmental noise is indeed crucial for excitation transport. At variance with this picture, we here address purely coherent transport on highly symmetric graphs, and show analytically that it is possible to enhance the transport efficiency without environmental noise, i.e., using only a minimal perturbation of the graph. In particular, we show that adding an extra weight to one or two edges, depending on whether the initial state is localized or in a superposition of two vertex states, breaks the inherent symmetries of the graph and may be sufficient to achieve unit transport efficiency. We also briefly discuss the conditions to obtain a null transport efficiency, i.e., to avoid trapping.
