Formalism where fundamental variables are nilpotent, but in contrast to the super-mathematics, not anticommutative but commutative gives another version of realization of the Pauli exclusion principle. We discuss some aspects of nilpotent quantum mechanics realized in generalized Hilbert space of functions of nilpotent commuting variables. The qubits are natural objects described by such a formalism. Supersymmetric system of qubit and fermion is presented. © 2011 Pleiades Publishing, Ltd.