Analytic formula for the geometric phase of an asymmetric top

The motion of a handle spinning in space has an odd behavior. It seems to unexpectedly flip back and forth in a periodic manner as seen in a popular YouTube video (“Plasma Ben, Dancing T-handle in zero-g, HD,” <https://www.youtube.com/watch?v=1n-HMSCDYtM>). As an asymmetrical top, its motion is completely described by the Euler equations and the equations of motion have been known for more than a century. However, recent concepts of the geometric phase have allowed a new perspective on this classical problem. Here, we explicitly use the equations of motion to find a closed form expression for the total phase and hence the geometric phase of the force-free asymmetric top and we explore some consequences of this formula with the particular example of the spinning handle for demonstration purposes. As one of the simplest dynamical systems, the asymmetric top should be a canonical example to explore the classical analog of the Berry phase.