Quantum phase-space distributions with compact support

Phase-space representations of quantum distributions such as the Wigner function and Kadanoff-Baym Green's functions do not have compact support which leads to difficulties for numerical and perturbative schemes in quantum transport simulations of nano-devices. We demonstrate that a useful complex-valued quantum phase-space distribution with compact support can be constructed. In many practical applications only the real part is required to obtain useful dynamical averages.