We consider operators acting on a UMD Banach lattice X that have the same algebraic structure as the position and momentum operators associated with the harmonic oscillator (Formula Presented) acting on L²(R^d). More precisely, we consider abstract harmonic oscillators of the form (Formula Presented) for tuples of operators (Formula Presented), where i A_j and iB_k are assumed to generate C₀ groups and to satisfy the canonical commutator relations. We prove functional calculus results for these abstract harmonic oscillators that match classical Hörmander spectral multiplier estimates for the harmonic oscillator (Formula Presented). This covers situations where the underlying metric measure space is not doubling and the use of function spaces that are not particularly well suited to extrapolation arguments. For instance, as an application we treat the harmonic oscillator on mixed norm Bargmann–Fock spaces. Our approach is based on a transference principle for the Schrödinger representation of the Heisenberg group that allows us to reduce the problem to the study of the twisted Laplacian on the Bochner spaces L²(R^2d; X). This can be seen as a generalisation of the Stone–von Neumann theorem to UMD lattices X that are not Hilbert spaces.