Easy Control over Fermionic Computations

Quantum fermionic computations on occupation numbers proposed in quant-ph/0003137 are studied. It is shown that a control over external field and tunneling would suffice to fulfill all quantum computations without valuable slowdown in the framework of such model when an interaction of diagonal type is fixed and permanent. Substantiation is given through a reduction of some subset of this model to the conventional language of quantum computing and application of the construction from quant-ph/0202030.