Seminarium "The Trans-Carpathian Seminar on Geometry & Physics"

I will consider the product of two rotations in three-dimensional space for which the rotation axes are perpendicular and the rotational angle is a rational multiple of pi and ask when if the obtained rotation angle is also a rational multiple of pi. The problem is reduced to finding the trigonometric minimal polynomial. I will show that this problem is related to quantum information theory. Joint work with Adam Sawicki.