  We examine a generic three state mechanism which realizes all fundamental
single and double qubit quantum logic gates operating under the effect of
adiabatically controllable static (radiation free) bias couplings between the
states. At the instant of time that the gate operations are defined the third
level is unoccupied which, in a certain sense, derives analogy with the
recently suggested dissipation free qubit subspaces. The physical
implementation of the mechanism is tentatively suggested in a form of the
Aharonov-Bohm persistent current loop in crossed electric and magnetic fields,
with the output of the loop read out by a (quantum) Hall effect aided
mechanism.
