美国耶鲁大学Songtao Huang团队研究了强驱动费米极化子。2025年4月7日出版的《自然—物理学》杂志发表了这项成果。
准粒子是物质的涌现激发，是人们对量子多体系统理解的基础。因此，控制其性质的前景具有根本性和现实意义。然而，在固态材料中，由于准粒子与其他集体激发的复杂相互作用，理解它们如何被外部场修改的通常颇具挑战性。
研究组演示了使用快速射频控制在均匀原子气体中操纵费米极化子，即由杂质与费米气体相互作用形成的准粒子。利用杂质物种的两种内部状态，他们开发了一种稳态光谱，从中提取了驱动极化子的能量。通过改变驱动拉比频率，测量了弱驱动极限下极化子的衰变率和准粒子残数。
在大拉比频率下，研究组观察到驱动导致受驱动极化子与非相干背景杂交的迹象，从而导致教科书中准粒子描述的崩溃。该实验将驱动费米极化子确立为研究强驱动量子物质中可控准粒子的有前景的平台，并呼吁建立一个受控的理论框架来描述这种强相互作用量子系统的动力学。
附：英文原文
Title: The strongly driven Fermi polaron
Author: Vivanco, Franklin J., Schuckert, Alexander, Huang, Songtao, Schumacher, Grant L., Assumpo, Gabriel G. T., Ji, Yunpeng, Chen, Jianyi, Knap, Michael, Navon, Nir
Issue&Volume: 2025-04-07
Abstract: Quasiparticles are emergent excitations of matter that underlie much of our understanding of quantum many-body systems. Therefore, the prospect of controlling their properties has both fundamental and practical implications. However, in solid-state materials, it is often challenging to understand how quasiparticles are modified by external fields due to their complex interplay with other collective excitations. Here we demonstrate the manipulation of Fermi polarons—quasiparticles formed by impurities interacting with a Fermi gas—in a homogeneous atomic gas using fast radio-frequency control. Exploiting two internal states of the impurity species, we develop a steady-state spectroscopy, from which we extract the energy of the driven polaron. By varying the drive Rabi frequency, we measure the decay rate and the quasiparticle residue of the polaron in the weak-drive limit. At large Rabi frequencies, we observe signs that the drive causes a hybridization of the driven polaron with an incoherent background, leading to the breakdown of a description in terms of textbook quasiparticles. Our experiment establishes the driven Fermi polaron as a promising platform for studying controllable quasiparticles in strongly driven quantum matter and calls for a controlled theoretical framework to describe the dynamics of this strongly interacting quantum system.
DOI: 10.1038/s41567-025-02799-8
Source: https://www.nature.com/articles/s41567-025-02799-8