Extending Quantum Links: Modules for Fiber- and Memory-Based Quantum Repeaters

TL;DR

This paper evaluates and compares quantum repeater modules based on fiber and memory stations across three physical platforms, aiming to enable secret key transmission over hundreds of kilometers.

Contribution

It introduces modular quantum repeater components tailored for different platforms and compares their performance under current and future experimental parameters.

Findings

Quantum dot platform suits high clock rates but has lower coherence.

Trapped atoms and ions offer longer coherence times, suitable for longer distances.

Protocols can be combined modularly to build scalable quantum repeater systems.

Abstract

We analyze elementary building blocks for quantum repeaters based on fiber channels and memory stations. Implementations are considered for three different physical platforms, for which suitable components are available: quantum dots, trapped atoms and ions, and color centers in diamond. We evaluate and compare the performances of basic quantum repeater links for these platforms both for present-day, state-of-the-art experimental parameters as well as for parameters that could in principle be reached in the future. The ultimate goal is to experimentally explore regimes at intermediate distances, up to a few 100 km, in which the repeater-assisted secret key transmission rates exceed the maximal rate achievable via direct transmission. We consider two different protocols, one of which is better adapted to the higher source clock rate and lower memory coherence time of the quantum dot platform, while the other circumvents the need of writing photonic quantum states into the memories in a heralded, non-destructive fashion. The elementary building blocks and protocols can be connected in a modular form to construct a quantum repeater system that is potentially scalable to large distances.