Curl forces and their role in optics and ion trapping

The position dependent nonconservative forces are called curl forces introduced recently by M.V. Berry, P. Shukla, J. Phys. A 45, 305201 (2012). In this article, we elucidate the role of curl forces in classical and quantum optics. At first we review the work of A. Ashkin and demonstrate the existence of curl force. We then discuss the role of curl force in ion trapping theory and map it to rotating saddle potential. Finally we show the connection between the two level atom problem, curl forces and their connection to Pais-Uhlenbeck oscillator.