  A reconfigurable logic gate is proposed in a two-dimensional double quantum
wire system with a coupling window enabled by a Rashba field. Manipulating the
spin states of incoming electrons several quantum logic gates (OR, AND, XOR,
CNOT) can be implemented. The logic gate functionality can be switched by
tuning the Rashba parameter only. In this context, we investigate suitable
configurations of the device region by embedding a quantum point contact
located in the coupling region to obtain all four logic gates. The ballistic
spin polarized transmission functions are calculated using an effective mass
scattering formalism in the framework of a multi-channel, multi-terminal
system. Owing its versatility, the proposed logic gate can be integrated in
programmable architectures, able to implement both classical and quantum
algorithms.
