  The quantum algebra suq(2) is introduced as a deformation of the ordinary Lie
algebra su(2). This is achieved in a simple way by making use of $q$-bosons. In
connection with the quantum algebra suq(2), we discuss the q-analogues of the
harmonic oscillator and the angular momentum. We also introduce q-analogues of
the hydrogen atom by means of a q-deformation of the Pauli equations and of the
so-called Kustaanheimo-Stiefel transformation.
