  We propose a deterministic SWAP gate for spatially encoded qubits. The gate
is constructed from waveguide crossings, Mach Zender Interferometers and phase
shifters providing the gate reconfigurability. Through manipulating the phase
of the phase shifters, we can apply either the SWAP or identity gates. As an
essential element of nearest neighbor qubit networks, the SWAP gate has a
simple structure and presents minimal overhead, making it viable for universal
quantum computation.
