Memory-assisted quantum key distribution resilient against multiple-excitation effects

Understand

Memory-assisted quantum key distribution (MA-QKD) has recently been proposed as a technique to improve the rate-versus-distance behavior of QKD systems by using existing, or nearly-achievable, quantum technologies.

• The promise is that MA-QKD would require less demanding quantum memories than the ones needed for probabilistic quantum repeaters.
• Nevertheless, early investigations suggest that, in order to beat the conventional no-memory QKD schemes, the quantum memories used in the MA-QKD protocols must have high bandwidth-storage products and short interaction times.
• Among different types of quantum memories, ensemble-based memories offer some of the required specifications, but they typically suffer from multiple excitation effects.