Please use this persistent identifier to cite or link to this item: doi:10.24405/14215
Title: System Approaches for a Practical Implementation of Continuous-Variable Quantum Key Distribution Using Coherent Heterodyne Detection
Authors: Kleis, Sebastian
Language: eng
Keywords: Optical Fiber Communication;CV-QKD;Quantum Cryptography;Heterodyne Detection;Carrier Phase Estimation;Bayesian Inference
Subject (DDC): 620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
Issue Date: 2022
Publisher: Universitätsbibliothek der HSU / UniBwH
Document Type: Thesis
Publisher Place: Hamburg
Public key cryptography is a cornerstone of today’s private communication. As quantum computing is a
major threat for the privacy of public key cryptography, the development of appropriate alternatives is
of critical importance. One promising alternative to achieve security against quantum computer attacks
is symmetric encryption, whereby the secret key is established using quantum key distribution (QKD).
Especially interesting for a wide application are continuous-variable QKD (CV-QKD) systems, as these can
potentially be implemented using standard components of coherent optical communications. However,
a major challenge for implementing CV-QKD is to achieve phase noise mitigation of the optical quantum
signal with a received power of less than 1 photon per symbol. In this thesis, two different approaches
for implementing CV-QKD systems and to overcome this challenge are proposed and investigated. To
achieve phase noise mitigation, a key element of both systems is the use of Bayesian inference methods
in the digital signal processing. Both systems rely on standard components and are therefore promising
for a practical implementation. Based on the experimental results, the suitability for CV-QKD is
confirmed, limiting factors are identified and the achievable performance is discussed. Additionally, the
compatibility of CV-QKD with existing optical networks is investigated based on system experiments with
a CV-QKD channel embedded in a commercial C band WDM system.
Organization Units (connected with the publication): Hochfrequenztechnik 
Advisor: Schäffer, Christian G.
Referee: Silberhorn, Christine
Grantor: HSU Hamburg
Type of thesis: Doctoral Thesis
Exam date: 2021-10-05
Appears in Collections:2 - Theses

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