Lei Qun-Li, Ciamarra Massimo Pica, Ni Ran
School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
Sci Adv. 2019 Jan 25;5(1):eaau7423. doi: 10.1126/sciadv.aau7423. eCollection 2019 Jan.
Disordered hyperuniform structures are an exotic state of matter having vanishing long-wavelength density fluctuations similar to perfect crystals but without long-range order. Although its importance in materials science has been brought to the fore in past decades, the rational design of experimentally realizable disordered strongly hyperuniform microstructures remains challenging. Here we find a new type of nonequilibrium fluid with strong hyperuniformity in two-dimensional systems of chiral active particles, where particles perform independent circular motions of the radius with the same handedness. This new hyperuniform fluid features a special length scale, i.e., the diameter of the circular trajectory of particles, below which large density fluctuations are observed. By developing a dynamic mean-field theory, we show that the large local density fluctuations can be explained as a motility-induced microphase separation, while the Fickian diffusion at large length scales and local center-of-mass-conserved noises are responsible for the global hyperuniformity.
无序超均匀结构是一种奇异的物质状态，其长波长密度涨落消失，类似于完美晶体，但没有长程序。尽管在过去几十年中它在材料科学中的重要性已被凸显，但合理设计可通过实验实现的无序强超均匀微观结构仍然具有挑战性。在此，我们在二维手性活性粒子系统中发现了一种具有强超均匀性的新型非平衡流体，其中粒子以相同的手性进行半径为 的独立圆周运动。这种新的超均匀流体具有一个特殊的长度尺度，即粒子圆周轨迹的直径，在该尺度以下会观察到较大的密度涨落。通过发展动态平均场理论，我们表明大的局部密度涨落可被解释为运动诱导的微相分离，而大长度尺度下的菲克扩散和局部质心守恒噪声则导致了整体的超均匀性。
