Mechanism of angular momentum transfer from microwaves to a copper ring

• Published in: The European physical journal. D, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2016, Vol.70 (8), p.1-9, Article 172
• Main Authors: Emile, Olivier, Niemiec, Ronan, Brousseau, Christian, Emile, Janine, Mahdjoubi, Kouroch, Wei, Wenlong, Thide, Bo
• Format: Article
• Language: English
• Subjects: Angular momentum; Applications of Nonlinear Dynamics and Chaos Theory; Atomic; Copper; Electromagnetic fields; Electromagnetic radiation; Electromagnetism; Microwaves; Molecular; Momentum transfer; Optical and Plasma Physics; Physical Chemistry; Physics; Physics and Astronomy; Quantum Information Technology; Quantum Physics; Regular Article; Spectroscopy/Spectrometry; Spintronics
• ISSN: 1434-6060; 1434-6079; 1434-6079
• DOI: 10.1140/epjd/e2016-70193-6

In the exchange of orbital angular momentum between an electromagnetic wave and a copper ring we examine the origin of the Angular Momentum. We then investigate the transfer mechanism between the microwave and the object, and compare it with other mechanisms. We evidence a transfer mechanism based on the reflection of the electromagnetic field on the copper ring. In particular, at a microscopic scale, we show that the electromagnetic field induces alternative electric currents in the ring, with a small drift. Although little, the resistivity of copper leads to a force that rotates the ring. The estimation of the torque, which is of the order of 10 -8 Nm, is in good agreement with the experimental measurements. We also show that the transfer of electromagnetic orbital angular momentum to objects could be a way to measure the orbital angular momentum carried by electromagnetic fields, and we discuss possible applications. Graphical abstract