  Most quantum computer realizations require the ability to apply local fields
and tune the couplings between qubits, in order to realize single bit and two
bit gates which are necessary for universal quantum computation. We present a
scheme to remove the necessity of switching the couplings between qubits for
two bit gates, which are more costly in many cases. Our strategy is to compute
in and out of carefully designed interaction free subspaces analogous to
decoherence free subspaces, which allows us to effectively turn off and turn on
the interactions between the encoded qubits. We give two examples to show how
universal quantum computation is realized in our scheme with local
manipulations to physical qubits only, for both diagonal and off diagonal
interactions.
