Kilometer-Scale Ion-Photon Entanglement with a Metastable ${}^{88}$Sr${}^{+}$ Qubit

Mika A. Zalewski, Denton Wu, Ana Luiza Ferrari +2

We demonstrate entanglement between the polarization of an infrared photon and a metastable ${}^{88}$Sr${}^{+}$ ion qubit. This entanglement persists after transmitting the photon over a…