Optimizing Brownian escape rates by potential shaping
Optimizing Brownian escape rates by potential shaping
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DOI：
10.1073/pnas.1910677116
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发表时间：
2020-01-21
影响因子：
11.1
通讯作者：
Trizac, Emmanuel
中科院分区：
文献类型：
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作者：
Chupeau, Marie;Gladrow, Jannes;Trizac, Emmanuel
布朗逃逸是许多物理化学过程的关键，包括聚合物折叠和信息存储。假设热激活能量势垒穿越的频率通常随着势垒高度的增加呈指数下降。在这里，我们通过实验证明，更高的、微调的势垒剖面会导致逃逸率显着提高，这违反了依赖于上述缩放定律的直觉，并在理论上解决了最大加速的相应条件。重要的是，我们的障碍结束时的能量与它们开始时的能量相同。对于过阻尼动力学，原则上可实现的逃逸率提升是无界的，因此必须对势垒优化进行正则化。我们在 2 种不同的正则化下得出最佳配置文件，并揭示了 N 形障碍的效率。然后，我们使用全息光镊在自动微流控布朗动力学实验中证明了这种潜力的可行性，并与不受阻碍的布朗运动相比，逃逸率提高了一倍。最后，我们证明这种逃逸率的提高延伸到了低摩擦惯性状态。
Brownian escape is key to a wealth of physico-chemical processes, including polymer folding and information storage. The frequency of thermally activated energy barrier crossings is assumed to generally decrease exponentially with increasing barrier height. Here, we show experimentally that higher, fine-tuned barrier profiles result in significantly enhanced escape rates, in breach of the intuition relying on the above scaling law, and address in theory the corresponding conditions for maximum speed-up. Importantly, our barriers end on the same energy on which they start. For overdamped dynamics, the achievable boost of escape rates is, in principle, unbounded so that the barrier optimization has to be regularized. We derive optimal profiles under 2 different regularizations and uncover the efficiency of N-shaped barriers. We then demonstrate the viability of such a potential in automated microfluidic Brownian dynamics experiments using holographic optical tweezers and achieve a doubling of escape rates compared to unhindered Brownian motion. Finally, we show that this escape rate boost extends into the low-friction inertial regime.