Title |
Fundamental limits of repeaterless quantum communications
|
---|---|
Published in |
Nature Communications, April 2017
|
DOI | 10.1038/ncomms15043 |
Pubmed ID | |
Authors |
Stefano Pirandola, Riccardo Laurenza, Carlo Ottaviani, Leonardo Banchi |
Abstract |
Quantum communications promises reliable transmission of quantum information, efficient distribution of entanglement and generation of completely secure keys. For all these tasks, we need to determine the optimal point-to-point rates that are achievable by two remote parties at the ends of a quantum channel, without restrictions on their local operations and classical communication, which can be unlimited and two-way. These two-way assisted capacities represent the ultimate rates that are reachable without quantum repeaters. Here, by constructing an upper bound based on the relative entropy of entanglement and devising a dimension-independent technique dubbed 'teleportation stretching', we establish these capacities for many fundamental channels, namely bosonic lossy channels, quantum-limited amplifiers, dephasing and erasure channels in arbitrary dimension. In particular, we exactly determine the fundamental rate-loss tradeoff affecting any protocol of quantum key distribution. Our findings set the limits of point-to-point quantum communications and provide precise and general benchmarks for quantum repeaters. |
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Professor | 14 | 4% |
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Other | 12 | 4% |
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