Uncertainty relation of the momentum components of a two-dimensional electron system under a tilted magnetic field

<div>A two-dimensional electron gas along the <em>xy</em>-plane is considered. When an applied perpendicular magnetic field, directed along the <em>z</em>-axis, is turned on, the electrons move in cyclotron orbits and the components of the momentum along the <em>x</em>- and <em>y</em>-axes do not commute.