丹麦哥本哈根大学Xiang Xi团队研究了声子的软箝位拓扑波导。相关论文于2025年6月4日发表在《自然》杂志上。

拓扑绝缘体最初是为凝聚态系统中的电子波发现的。最近，这一概念已被转移到玻色子系统，如光子和声子，它们在模拟自旋霍尔物理的人造晶格图案化的材料中传播。这项工作的部分动机是在片上电路中沿边缘通道进行拓扑保护传输的前景。原则上，拓扑结构可以保护传播免受后向散射的影响，但不能防止损耗，声子波导损耗一直限制在dB cm^-1级以内，无论是否拓扑。 

研究组将先进的耗散工程，特别是最近引入的软箝位方法，与声子谷霍尔拓扑绝缘体的概念相结合。这使得片上声子波导的传播损耗在室温下为3 dB km^-1，比任何以前的芯片级设备低几个数量级。低损耗还使他们能够使用高分辨率超声光谱学准确量化拓扑声子波导中的后向散射保护。

研究组推断，声子以99.99%的概率遵循120°的急剧弯曲，而不是被散射回去，并且损失的声子不到百万分之一。该工作将激发超低损耗声子波导的新研究方向，并为研究拓扑保护和非厄米拓扑物理学提供一个干净的玻色子系统。

附：英文原文

Title: A soft-clamped topological waveguide for phonons

Author: Xi, Xiang, Chernobrovkin, Ilia, Koata, Jan, Kristensen, Mads B., Langman, Eric, Srensen, Anders S., Zilberberg, Oded, Schliesser, Albert

Issue&Volume: 2025-06-04

Abstract: Topological insulators were originally discovered for electron waves in condensed-matter systems. Recently, this concept has been transferred to bosonic systems such as photons1 and phonons2, which propagate in materials patterned with artificial lattices that emulate spin-Hall physics. This work has been motivated, in part, by the prospect of topologically protected transport along edge channels in on-chip circuits2,3. In principle, topology protects propagation against backscattering, but not against loss, which has remained limited to the dBcm1 level for phononic waveguides, whether topological4,5,6,7 or not8,9,10,11,12,13,14,15,16,17,18,19. Here we combine advanced dissipation engineering20—in particular, the recently introduced method of soft clamping21—with the concept of valley-Hall topological insulators for phonons22,23,24,25,26. This enables on-chip phononic waveguides with propagation losses due to dissipation of 3dBkm1 at room temperature, orders of magnitude below any previous chip-scale devices. The low losses also allow us to accurately quantify backscattering protection in topological phononic waveguides, using high-resolution ultrasound spectroscopy. We infer that phonons follow a sharp, 120° bend with a 99.99% probability instead of being scattered back, and less than one phonon in a million is lost. Our work will inspire new research directions on ultralow-loss phononic waveguides and will provide a clean bosonic system for investigating topological protection and non-Hermitian topological physics.

DOI: 10.1038/s41586-025-09092-x

Source: https://www.nature.com/articles/s41586-025-09092-x