Quantum Key Distribution over Probabilistic Quantum Repeaters

Abstract

A feasible route towards implementing long-distance quantum key distribution (QKD) systems relies on probabilistic schemes for entanglement distribution and swapping as proposed in the work of Duan, Lukin, Cirac, and Zoller (DLCZ) [Nature 414, 413 (2001)]. Here, we calculate the conditional throughput and fidelity of entanglement for DLCZ quantum repeaters, by accounting for the DLCZ self-purification property, in the presence of multiple excitations in the ensemble memories as well as loss and other sources of inefficiency in the channel and measurement modules. We then use our results to find the generation rate of secure key bits for QKD systems that rely on DLCZ quantum repeaters. We compare the key generation rate per logical memory employed in the two cases of with and without a repeater node. We find the cross-over distance beyond which the repeater system outperforms the non-repeater one. That provides us with the optimum inter-node distancing in quantum repeater systems. We also find the optimal excitation probability at which the QKD rate peaks. Such an optimum probability, in most regimes of interest, is insensitive to the total distance.

12 pages, 6 figures; Fig. 5(a) is replaced

References in corpus (7)

• A millisecond quantum memory for scalable quantum networks
• Robust and Efficient Quantum Repeaters with Atomic Ensembles and Linear Optics
• Squashing Models for Optical Measurements in Quantum Communication
• A fast and robust approach to long-distance quantum communication with atomic ensembles
• Quantum repeaters with imperfect memories: cost and scalability
• Security proof for QKD systems with threshold detectors
• Robust quantum repeater with atomic ensembles against phase and polarization instability

Cited by in corpus (14)

• Advances in Quantum Cryptography
• NetSquid, a NETwork Simulator for QUantum Information using Discrete events
• Alternative schemes for measurement-device-independent quantum key distribution
• Memory-assisted measurement-device-independent quantum key distribution
• Multiple-Access Quantum Key Distribution Networks
• Quantum repeaters and quantum key distribution: analysis of secret key rates
• Long-distance practical quantum key distribution by entanglement swapping
• Quantum repeaters and quantum key distribution: the impact of entanglement distillation on the secret key rate
• Memory-Assisted Quantum Key Distribution with a Single Nitrogen Vacancy Center
• Requirements for a processing-node quantum repeater on a real-world fiber grid
• Repeat-until-success quantum repeaters
• Long-distance quantum key distribution with imperfect devices
• Multi-party quantum summation based on quantum teleportation
• Simple efficient decoders for quantum key distribution over quantum repeaters with encoding