Lee Jae Sung, Park Jong-Min, Park Hyunggyu
School of Physics and Quantum Universe Center, Korea Institute for Advanced Study, Seoul 02455, Korea.
Phys Rev E. 2020 Sep;102(3-1):032116. doi: 10.1103/PhysRevE.102.032116.
Microorganisms such as bacteria are active matter which consume chemical energy and generate their unique run-and-tumble motion. A swarm of such microorganisms provide a nonequilibrium active environment whose noise characteristics are different from those of thermal equilibrium reservoirs. One important difference is a finite persistence time, which is considerably large compared to that of the equilibrium noise, that is, the active noise is colored. Here we study a mesoscopic energy-harvesting device (engine) with active reservoirs harnessing this noise nature. For an exactly solvable linear model, we show that the performance from the active environment can surpass that from the equilibrium environment. Furthermore, we propose a proper definition of the active-reservoir temperature and show that the engine efficiency can overcome the conventional Carnot bound, thus the power-efficiency trade-off constraint is released. We also show that the efficiency at the maximum power can surpass the Curzon-Ahlborn efficiency. This remarkable enhancement originates from the extra unconventional entropy production beyond the conventional Clausius entropy production, due to the non-Markovian nature of the active reservoirs. Interestingly, the supremacy of the active engine critically depends on the timescale symmetry of two active reservoirs.
诸如细菌之类的微生物是活性物质，它们消耗化学能量并产生独特的“跑-停”运动。一群这样的微生物提供了一个非平衡活性环境，其噪声特性不同于热平衡库的噪声特性。一个重要的区别是有限的持续时间，与平衡噪声相比，这个持续时间相当长，也就是说，活性噪声是有色噪声。在这里，我们研究一种带有活性库的介观能量收集装置（发动机），该装置利用这种噪声特性。对于一个可精确求解的线性模型，我们表明来自活性环境的性能可以超过来自平衡环境的性能。此外，我们提出了活性库温度的恰当定义，并表明发动机效率可以克服传统的卡诺界限，从而释放了功率-效率权衡约束。我们还表明最大功率下的效率可以超过柯曾-阿尔博恩效率。这种显著的提高源于活性库的非马尔可夫性质所导致的、超出传统克劳修斯熵产生的额外非传统熵产生。有趣的是，活性发动机的优越性关键取决于两个活性库的时间尺度对称性。
