近日，美国马里兰大学的Mohammad Hafezi及其研究团队取得一项新进展。经过不懈努力，他们利用涡旋光对电子量子霍尔态进行光泵浦。相关研究成果已于2024年11月26日在国际知名学术期刊《自然—光子学》上发表。
本文提出一种将光学涡旋光束的轨道角动量转移到电子量子霍尔态的机制。具体而言，研究人员在量子霍尔效应范围内的环形石墨烯样品中，发现一种对径向光电流有显著贡献的效应，该效应取决于光的涡旋性。
这一现象可解释为一种光泵浦方案，其中光子的角动量被转移到电子上，从而产生径向电流，且电流方向由光的涡旋性决定。这项研究结果为光学探测和操纵量子相干性提供了基本见解，对推动量子相干光电子学的发展具有广泛意义。
据悉，量子技术的一个基本要求是能够相干地控制电子与光子之间的相互作用。然而，在许多涉及光与物质相互作用的场景中，电子与光子之间线性动量或角动量的交换并不可行，这一条件被称为偶极近似极限。一个超出此极限但实验上难以实现的情况是，当考虑手性电子与涡旋光之间的相互作用时，光的轨道角动量可以传递给电子。
附：英文原文
Title: Optical pumping of electronic quantum Hall states with vortex light
Author: Session, Deric, Jalali Mehrabad, Mahmoud, Paithankar, Nikil, Grass, Tobias, Eckhardt, Christian J., Cao, Bin, Gustavo Surez Forero, Daniel, Li, Kevin, Alam, Mohammad S., Watanabe, Kenji, Taniguchi, Takashi, Solomon, Glenn S., Schine, Nathan, Sau, Jay, Sordan, Roman, Hafezi, Mohammad
Issue&Volume: 2024-11-26
Abstract: A fundamental requirement for quantum technologies is the ability to coherently control the interaction between electrons and photons. However, in many scenarios involving the interaction between light and matter, the exchange of linear or angular momentum between electrons and photons is not feasible, a condition known as the dipole approximation limit. An example of a case beyond this limit that has remained experimentally elusive is when the interplay between chiral electrons and vortex light is considered, where the orbital angular momentum of light can be transferred to electrons. Here we present a mechanism for such an orbital angular momentum transfer from optical vortex beams to electronic quantum Hall states. Specifically, we identify a robust contribution to the radial photocurrent, in an annular graphene sample within the quantum Hall regime, that depends on the vorticity of light. This phenomenon can be interpreted as an optical pumping scheme, where the angular momentum of photons is transferred to electrons, generating a radial current, and the current direction is determined by the vorticity of the light. Our findings offer fundamental insights into the optical probing and manipulation of quantum coherence, with wide-ranging implications for advancing quantum coherent optoelectronics.
DOI: 10.1038/s41566-024-01565-1
Source: https://www.nature.com/articles/s41566-024-01565-1