Linear optical deterministic and reconfigurable SWAP gate

We propose a deterministic SWAP gate for dual-rail-encoded single photon qubits. The is constructed from waveguide crossings, Mach–Zehnder interferometers and phase shifters which provide the reconfigurability. Through manipulating of shifters, we can apply either or identity gates. As an essential element nearest neighbor qubit networks, has simple structure presents minimal overhead. Providing efficient solution to geometric restrictions on-chip dual-rail circuits, our design may be utilized in applying large scale arbitrary unitary transformations.