Two-photon controlled-phase gates enabled by photonic dimers

Photons are appealing as flying quantum bits due to their low-noise, long coherence times, light-speed transmission, and ease of manipulation at the single-qubit level using standard optical components such as beam splitters and waveguides. The challenge in optical quantum information processing has been the realization of two-qubit gates for photonic qubits due to the lack of highly efficient optical Kerr nonlinearities at the single-photon level. To date, only probabilistic two-qubit photonic controlled-phase gates based on linear optics and projective measurement using photon detectors have been demonstrated. Here we show that a high-fidelity frequency-encoded deterministic two-photon controlled-phase gate can be achieved by exploiting the strong photon-photon correlation enabled by photonic dimers, and the unique nonreciprocal photonic propagation in chiral quantum nanophotonic systems.

Automated summary

Photons are attractive for flying quantum bits due to their low noise, long coherence times, and ease of manipulation. However, the challenge lies in realizing two-qubit gates for photonic qubits. So far, only probabilistic optical controlled-phase gates have been demonstrated.