Photonic Controlled-Phase Gate Based on Rydberg Interactions

Aaron M. Hankin, Yuan‐Yu Jau, Grant W. Biedermann

Shi‐Lei Su

Tyler Keating, Ivan Deutsch, Robert L. Cook +2 more

Sumanta Das, Andrey Grankin, Ivan Iakoupov +7 more

We propose a scheme for high-fidelity photonic controlled-phase gates using a Rydberg blockade in an ensemble of atoms in an optical cavity. The gate operation is obtained by first storing a photonic pulse in the ensemble and then scattering a second pulse from the cavity, resulting in a phase change depending on whether the first pulse contained a single photon. We show that the combination of a Rydberg blockade and optical cavities effectively enhances the optical nonlinearity created by the strong Rydberg interaction and makes the gate operation more robust. The resulting gate can be implemented with cavities of moderate finesse, allowing for highly efficient processing of quantum information encoded in photons. As an illustration, we show how the gate can be employed to increase the communication rate of quantum repeaters based on atomic ensembles.

Daniel Tiarks, Steffen Schmidt-Eberle, Thomas Stolz +2 more

Mohammadsadegh Khazali, Khabat Heshami, Christoph Simon

We propose a scheme for a deterministic controlled-phase gate between two photons that is based on the strong interaction between two stationary collective Rydberg excitations in an atomic ensemble outside the regime of Rydberg blockade. The distance-dependent character of the interaction causes both a momentum displacement of the collective excitations and unwanted entanglement between them. We show that these effects can be overcome by swapping the collective excitations in space and by optimizing the geometry, resulting in a photon-photon gate with high fidelity and efficiency.