Entanglement tracking and EPL entanglement generation in quantum networks using the discrete event simulator QNetSquid

Master thesis (2018)

Authors

R.S. ter Hoeven Applied Sciences

Contributors

S.D.C. Wehner (supervisor 1)
F.D. Rozpedek (supervisor 1)
Faculty
Applied Sciences
Copyright: © 2018 Roeland ter Hoeven
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Published Date

24-08-2018

Language

English

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Faculty

Applied Sciences

Abstract

The realisation of a quantum network in the near future has been made possible by the developments in qubit systems. Links between quantum nodes in major cities in The Netherlands are scheduled to be demonstrated by 2020. There are many things that need to be considered in the development of a quantum network, in this thesis a few of these will be examined. The first topic is entanglement generation using the EPL (Extreme Photon Loss) protocol in the presence of dephasing noise, which is an existing protocol. Novel contributions include the maximum achievable fidelities and entanglement generation rates, which are obtained using theoretical analysis and numerical simulations. Also for elementary states generated by the EPL protocol it is shown that doing distillation first and then an entanglement swap results in a roughly two times higher rate than the other way around.

A new protocol called entanglement tracking is proposed to keep track of the classical information about entanglement in a quantum network. The entanglement tracker is a protocol that runs locally on every node in a quantum network and can communicate with the entanglement trackers of other nodes. The goal of the entanglement tracker is to keep a database with entanglement identifiers that is continuously updated after entanglement is modified. Performance metrics of an entanglement tracking protocol and a command interface with higher layer protocols are defined. We propose a format for entanglement identifiers and show how to update entanglement identifiers after an arbitrary number of entanglement swaps. The entanglement tracker is implemented in the discrete event simulator QNetSquid, which is under development by QuTech. It is applied by simulating a repeater chain using the entanglement tracking protocol, resulting in a completion time as a function of the number of repeaters. Future applications of the entanglement tracker are to assist routing of entanglement in a (large) quantum network, in which the tracker can take care of the classical communication.