Stuttgart 2012 – scientific programme

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SYPC: Symposium From Atoms to Photonic Circuits: Integrating Quantum Optics and Optical Communication

SYPC 3: From Atoms to Photonic Circuits: Integrating Quantum Optics and Optical Communication 3

SYPC 3.2: Talk

Friday, March 16, 2012, 10:45–11:00, V47.02

Heralded Quantum Entanglement between two Crystals — •Christoph Clausen, Imam Usmani, Félix Bussières, Nicolas Sangouard, Mikael Afzelius, and Nicolas Gisin — GAP-Optique, Université de Genève, Switzerland

A crucial requirement for quantum networks is the ability to entangle quantum nodes. With the help of a quantum repeater, for example, quantum information can be transmitted at a rate that scales polynomially with distance, whereas the exponential loss in direct transmission of single photons through optical fibers inhibits quantum communication over distances larger than a few hundred kilometers. This is only possible if two remote quantum memories can be entangled in a heralded fashion.

We present the creation of heralded entanglement between two ensembles of rare-earth ions doped into separate crystals. A heralded single photon is sent through a 50/50 beamsplitter with one crystal at each output acting as quantum memories. The absorption of the photon by one of the crystals leads to a single collective excitation delocalized between the two crystals. The entanglement between the crystals is revealed by mapping it back to optical modes and performing a series of measurements that provide a lower bound on the concurrence of the retrieved light state. Our results are a step on the way towards quantum networks based on solid-state resources.