Chiral route to spontaneous entanglement generation

We study the spontaneous entanglement generation between two qubits chirally coupled to a waveguide. The maximum achievable concurrence is demonstrated to increase by a factor of 4/e similar to 1.5 as compared to the non-chiral coupling situation. The proposed entanglement scheme is shown to be robust against variation of the qubit properties such as detuning and separation, which are critical in the nonchiral case. This result relaxes the restrictive requirements of the nonchiral situation, paving the way toward a realistic implementation. Our results demonstrate the potential of chiral waveguides for quantum entanglement protocols.