Stikuts Andris P, Mishra Seemant, Ryabov Artem, Maass Philipp, Tierno Pietro
Departament de Física de la Matèria Condensada, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Spain.
University of Barcelona Institute of Complex Systems (UBICS), Carrer de Martí i Franqués 1, 08028 Barcelona, Spain.
Nat Commun. 2025 Mar 26;16(1):2966. doi: 10.1038/s41467-025-58217-3.
Shapiro steps are quantized plateaus in the velocity-force or velocity-torque curve of a driven system, when its speed remains constant despite an increase in the driving force. For microscopic particles driven across a sinusoidal potential, integer Shapiro steps have been observed. By driving a single colloidal particle across a time-modulated, non-sinusoidal periodic optical landscape, we here demonstrate that fractional Shapiro steps emerge in addition to integer ones. Measuring the particle position via individual particle tracking, we reveal the underlying microscopic mechanisms that produce integer and fractional steps and demonstrate how these steps can be controlled by tuning the shape and driving protocol of the optical potential. The flexibility offered by optical engineering allows us to generate a wide range of potential shapes and to study, at the single-particle level, synchronization behavior in driven soft condensed matter systems.
夏皮罗台阶是驱动系统速度-力或速度-扭矩曲线中的量化平台，此时尽管驱动力增加，其速度仍保持恒定。对于在正弦势中驱动的微观粒子，已经观察到整数夏皮罗台阶。通过驱动单个胶体粒子穿过时间调制的非正弦周期性光学势场，我们在此证明除了整数台阶外还会出现分数夏皮罗台阶。通过单个粒子跟踪测量粒子位置，我们揭示了产生整数和分数台阶的潜在微观机制，并展示了如何通过调整光学势的形状和驱动协议来控制这些台阶。光学工程提供的灵活性使我们能够生成各种势场形状，并在单粒子水平上研究驱动软凝聚态系统中的同步行为。
