Investigating the Scalability of Quantum Repeater Protocols Based on Atomic Ensembles

Abstract

A Quantum Internet will enable new applications that are provably impossible with classical communication alone. However, the optical fibers used to carry the quantum information are inherently lossy. To overcome the exponential losses over distance so-called quantum repeaters are needed to amplify the signal.
In this thesis we investigate the performance of different repeater architectures within the European Quantum Internet Alliance which are based on atomic ensemble technology.
For each of the groups from Barcelona, Delft, Geneva and Paris we simulate different sets of current and future performance parameters.
In contrast to previous simulations and analytical models we present the first simulation that includes important sources of error for these types of architectures, such as multi-pair emission, time-dependent memory efficiency and photon distinguishability. Key to this is our new approach using discrete event simulation never used before for atomic ensemble based quantum repeater protocols.
We find that previous models do not accurately describe the performance of such repeater architectures and provide an analysis of how each of these noise parameters impacts performance. This allows us to assess the potential of different component technologies, such as photon sources and quantum memories, and quantify what improvements are necessary to bridge long distances in the future.
With our simulation we provide a crucial stepping stone towards a blueprint for a pan-European Quantum Internet.