Novel approaches towards non-cryogenic quantum repeaters

Abstract

The successful implementation of global quantum networks would have many applications such as secure communication, blind quantum computing, and private database queries, ultimately leading to a "quantum internet" of networked quantum processors. This will require photons for establishing long-distance connections. However, the inevitable losses in transmission and the fact that they cannot be compensated by amplification significantly limit the distance. Therefore, quantum repeaters have been proposed to solve this issue but this typically requires stationary quantum memories for storing and processing the quantum information. Currently, a vast majority of approaches to quantum networks need either vacuum equipment and optical trapping or cryogenic cooling, which makes scaling up such architectures very difficult. In this thesis, we explore two hardware platforms for realizing quantum repeaters that can operate without cryogenics: nitrogen-vacancy (NV) centers and optomechanics-based repeaters and hot hybrid alkali-noble gases-based repeaters. We show how entanglement generation and entanglement swapping can be achieved in both schemes. Moreover, we quantify the performance of these two proposed repeater architectures in terms of repeater rates and overall entanglement fidelities and make a comparison between them. We also discuss the experimental feasibility of these two schemes, demonstrating that both can be within reach of current technologies.