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A memory-based quantum network node with a trapped ion in an optical fibre cavity

dc.contributor.advisorKöhl, Michael
dc.contributor.authorKobel, Pascal
dc.date.accessioned2022-06-17T10:24:37Z
dc.date.available2022-06-17T10:24:37Z
dc.date.issued17.06.2022
dc.identifier.urihttps://hdl.handle.net/20.500.11811/9873
dc.description.abstractExploiting quantum effects in the communication between different systems promise great capabilities as distributed quantum computing or provably secure communication. In this thesis we present the realisation of a memory-based quantum network node as a basic building block for quantum communication. The network node comprises of a single trapped ion as a stationary qubit, which is coupled to a light-matter interface linking the ion to a photonic communication channel. We present the application of an optical resonator, which consists of two opposing mirrors that we have realised at the end of two optical fibres. The small resonator volume (mode volume) increases the light-matter interaction rate, allowing a high bandwidth for the distribution of quantum information in a network via optical photons. In addition, the fibre-based resonator provides intrinsic coupling of the photons to optical fibres, which greatly simplifies their distribution in a network.
We demonstrate the first generation of quantum entanglement between a stationary qubit and a photon, with an optical fibre resonator as the interface between both qubits. Since a quantum state cannot be copied and transmitted classically, entanglement is essential for the purpose of quantum communication. We show that even at a distance (about 1.5 m) the ion and the photon share a common entangled quantum state with a high fidelity of (90.1 ± 1.7)%. The entangled state is generated on-demand by the deterministic excitation of the ion, where we achieve a detection rate of 62 Hz, enabled by the efficient interface between ion and photon.
The presented entanglement between an atom and a photon as two different types of qubits allows us to combine the advantages of information storage (atom) and long range distribution of quantum information (photon). In this context, we demonstrate the first implementation of a provably secure quantum key distribution (QKD) between two remote parties involving an entangled memory qubit. The presented method hereby addresses two principal challenges of quantum key distribution, namely key generation and long-range application. We show that the fundamental quantum mechanical properties of the entangled two-qubit state allow us to generate a key with certifiable randomness, which in this strong form is not possible classically. Furthermore, the presented methods of memory-based key distribution are particularly applicable in the context of quantum repeaters, in which quantum information is temporarily stored before further distribution. This enables long-range key distribution even beyond the point-to-point limit of optical quantum communication, which results from the absorption properties of optical photons as information carriers.
en
dc.language.isoeng
dc.rightsNamensnennung 4.0 International
dc.subjectVerschränkung
dc.subjectIon
dc.subjectPhoton
dc.subjectGlasfaser
dc.subjectoptischer Resonator
dc.subjectQuantenschlüsselverteilung
dc.subjectQuantenschlüsselaustausch
dc.subjectZertifizierbare Zufälligkeit
dc.subjectLicht-Materie Schnittstelle
dc.subjectYtterbium
dc.subjectYb
dc.subjectSpeicher-Qubit
dc.subjectQuantenspeicher
dc.subjectQuantennetzwerkknoten
dc.subjectkohärente Manipulation
dc.subjectQuanteninformation
dc.subjectmaschinelles Lernen
dc.subjectParameter Optimierung
dc.subjectPaul Falle
dc.subjectNadel-Falle
dc.subjectBell Ungleichungen
dc.subjectLicht-Materie Kopplung
dc.subjectQuantenkommunikation
dc.subjectDichtematrix
dc.subjectQuantentomographie
dc.subjectAtom-Photon Verschränkung
dc.subjectEntanglement
dc.subjectfiber
dc.subjectcavity
dc.subjectoptical resonator
dc.subjectQKD
dc.subjectquantum key distribution
dc.subjectcertifiable randomness
dc.subjectquantum memory
dc.subjectlight-matter interface
dc.subjectmemory qubit
dc.subjectquantum network node
dc.subjectcoherent spin manipulation
dc.subjectquantum information
dc.subjectmachine learning
dc.subjectparameter optimization
dc.subjectexperimental calibration
dc.subjectmicromotion
dc.subjectPaul trap
dc.subjectatom-photon entanglement
dc.subjectBell inequalities
dc.subjectBell violation
dc.subjectnon-locality
dc.subjectquantum link
dc.subjectlight-matter coupling
dc.subjectquantum communication
dc.subjectUltra-fast Rabi-flops
dc.subjectdensity matrix
dc.subjectquantum tomography
dc.subject.ddc530 Physik
dc.titleA memory-based quantum network node with a trapped ion in an optical fibre cavity
dc.typeDissertation oder Habilitation
dc.publisher.nameUniversitäts- und Landesbibliothek Bonn
dc.publisher.locationBonn
dc.rights.accessRightsopenAccess
dc.identifier.urnhttps://nbn-resolving.org/urn:nbn:de:hbz:5-65559
dc.relation.arxiv2111.14523
dc.relation.arxiv2005.09119
dc.relation.doihttps://doi.org/10.1038/s41534-020-00338-2
ulbbn.pubtypeErstveröffentlichung
ulbbnediss.affiliation.nameRheinische Friedrich-Wilhelms-Universität Bonn
ulbbnediss.affiliation.locationBonn
ulbbnediss.thesis.levelDissertation
ulbbnediss.dissID6555
ulbbnediss.date.accepted06.10.2021
ulbbnediss.instituteMathematisch-Naturwissenschaftliche Fakultät : Fachgruppe Physik/Astronomie / Physikalisches Institut (PI)
ulbbnediss.fakultaetMathematisch-Naturwissenschaftliche Fakultät
dc.contributor.coRefereeHofferberth, Sebastian
ulbbnediss.contributor.orcidhttps://orcid.org/0000-0002-7562-1544
ulbbnediss.contributor.gnd1260507823


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