You can find the online document here.
Publication appeared in Scientific Reports
Two-qubit operations for single-rail encoded qubits. (a) Only the restricted set of trivial two-qubit gates prohibits photon-bunching. (b) When using non-trivial two-qubit gates, such as the control-NOT or control-Phase gate, photon-bunching cannot be avoided and thus leads to gate errors or probabilistic success rates.