Spreeuw Robert J C
Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, PO Box 94485, Amsterdam 1090 GL, The Netherlands.
QuSoft, Science Park 123, Amsterdam 1098 XG, The Netherlands.
Nanophotonics. 2021 Nov 11;11(4):633-644. doi: 10.1515/nanoph-2021-0458. eCollection 2022 Jan.
The insight that optical vortex beams carry orbital angular momentum (OAM), which emerged in Leiden about 30 years ago, has since led to an ever expanding range of applications and follow-up studies. This paper starts with a short personal account of how these concepts arose. This is followed by a description of some recent ideas where the coupling of transverse orbital and spin angular momentum (SAM) in tightly focused laser beams produces interesting new effects. The deflection of a focused light beam by an atom in the focus is reminiscent of the Magnus effect known from aerodynamics. Momentum conservation dictates an accompanying light force on the atom, transverse to the optical axis. As a consequence, an atom held in an optical tweezer will be trapped at a small distance of up to /2 away from the optical axis, which depends on the spin state of the atom and the magnetic field direction. This opens up new avenues to control the state of motion of atoms in optical tweezers as well as potential applications in quantum gates and interferometry.
大约30年前在莱顿出现的关于光学涡旋光束携带轨道角动量（OAM）的见解，此后引发了一系列不断扩展的应用和后续研究。本文首先简要介绍这些概念是如何产生的。接着描述一些近期的观点，即在紧聚焦激光束中横向轨道角动量和自旋角动量（SAM）的耦合产生了有趣的新效应。焦点处的原子使聚焦光束发生偏转，这让人联想到空气动力学中的马格努斯效应。动量守恒决定了在垂直于光轴方向上作用于原子的伴随光力。因此，被捕获在光镊中的原子将被捕获在距离光轴最大为λ/2的小距离处，这取决于原子的自旋状态和磁场方向。这为控制光镊中原子的运动状态开辟了新途径，以及在量子门和干涉测量中的潜在应用。
