Direction-switchable single-photon emitter using a Rydberg polariton

A promising route toward quantum networking is via photons as information carriers, requiring deterministic quantum nonlinear optical operations and single-photon routing. Here, we demonstrate a direction-switchable single-photon emitter using a Rydberg polariton. The Rydberg component of the stored photon is changed using a stimulated Raman transition with a specific intermediate state. By adjusting the direction of the retrieval laser, we can redirect the emitted photon into a rich variety of alternative modes. We experimentally demonstrate a redirection angle of ∼100 ∘ . Building upon this scheme, we propose a quantum routing of single photons with N output channels by rotation of the retrieval laser, where all directions have identical routing efficiency. In addition, the protocol reduces the effect of motional dephasing, increasing the photon lifetime to >10µs (>20 times the photon processing time), enabling functional quantum devices based on Rydberg polaritons.