Super K\"ahler oscillator from SU(2|1) superspace

We construct a new version of the worldline SU(2|1) superspace as a deformation of the standard N =4, d=1 superspace and show that it naturally provides off- and on-shell description of general supersymmetric K\"ahler oscillator model considered earlier at the classical level within the Hamiltonian approach. The basic object is a generalized chiral SU(2|1), d=1 superfield with the off-shell field content (2, 4, 2). The frequency of the oscillator and the strength of external magnetic field are defined by two parameters: the contraction parameter $m$ and the new parameter $\lambda$ which reflects the freedom in defining the chiral SU(2|1), d=1 superspace. We treat both classical and quantum cases.