General Benchmarks for Quantum Repeaters

TL;DR

This paper establishes fundamental limits and benchmarks for quantum repeaters and communication over various quantum channels, using a teleportation-based technique to derive exact capacities and bounds in both discrete and continuous-variable systems.

Contribution

It introduces a unified teleportation-based method to bound and compute capacities of diverse quantum channels, providing the most general benchmarks for quantum repeaters.

Findings

Exact two-way capacities for bosonic amplifier and dephasing channels derived.

Secret key capacity of the qubit erasure channel determined.

Established fundamental limits for quantum communication across various systems.

Abstract

Using a technique based on quantum teleportation, we simplify the most general adaptive protocols for key distribution, entanglement distillation and quantum communication over a wide class of quantum channels in arbitrary dimension. Thanks to this method, we bound the ultimate rates for secret key generation and quantum communication through single-mode Gaussian channels and several discrete-variable channels. In particular, we derive exact formulas for the two-way assisted capacities of the bosonic quantum-limited amplifier and the dephasing channel in arbitrary dimension, as well as the secret key capacity of the qubit erasure channel. Our results establish the limits of quantum communication with arbitrary systems and set the most general and precise benchmarks for testing quantum repeaters in both discrete- and continuous-variable settings.