Vortex electromagnetic wave with high gain has excellent potential in terahertz communication systems. In this paper, a Cassegrain antenna that can generate a high-gain orbital angular momentum (OAM) ...

The ability to rapidly switch between orbital angular momentum modes of light has important implications for future classical and quantum systems. In general, orbital angular momentum beams are ...

Since momentum is a vector, I will have to plot one component of the momentum—just for fun, I will choose the x-coordinate. Here's what I get.

For example, imagine catching a ball. When the ball is moving, it has momentum. You have to exert a force with your hand to stop the ball (and bring its momentum down to zero).