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Q: Fachverband Quantenoptik und Photonik

Q 17: Quantum Repeater and Quantum Communication

Q 17.2: Vortrag

Dienstag, 7. März 2017, 11:15–11:30, P 3

Cavity-enhanced quantum memory at telecommunication wavelength — •Benjamin Merkel, Natalie Wilson, and Andreas Reiserer — Max Planck Institute of Quantum Optics, Garching, Germany

Quantum networks are based on the distribution of entangled photon pairs between distant nodes. Ideally, the photonic links have to operate at telecommunication wavelengths, where loss in glass fibers is minimal, and one has to implement fault-tolerant quantum repeater protocols. The exceptional coherence properties of rare-earth-ions in crystalline hosts have made them a prime candidate for the implementation of such quantum repeaters. In particular, Erbium has an optical transition at a telecom wavelength, for which ensemble-based quantum memories have already been demonstrated. However, the dipole-dipole interaction between densely-packed Erbium ions poses a limit to the achievable coherence time.

To overcome this challenge, we use crystals with a very low impurity concentration. While this minimizes ion-ion interaction and thus enables long coherence times, it comes at the price of a reduced memory efficiency caused by the lower optical depth. We therefore investigate embedding the crystals into optical resonators to enhance the ion-photon coupling. In the limit of weak doping, high resonator quality factor and small mode volume, this approach might even enable us to resolve and control single Erbium ions in a crystal, making them a unique resource for the implementation of global-scale quantum networks.