Starting from the holomorphic discrete series of SU(1, 1), we construc
t a hyperbolic analogue of a quantum mechanical harmonic oscillator wi
th a Poincare disc as nonlinear phase space. A Bargmann-type transform
is established which interwines the real wave and complex wave repres
entation. The probability distribution of the position observable in v
acuum is calculated explicitly, it admits the Gaussian law of the ordi
nary harmonic oscillator as zero-curvature limit.