JULIA NEUWIRTH

Dottoressa di ricerca

ciclo: XXXV


relatore: Prof. Rinaldo Trotta
co-supervisore: Prof. Fabio Sciarrino

Titolo della tesi: Semiconductor quantum dots for photonic quantum repeaters

Current information exchange is based on optical fibers and satellite communication via free-space links, where security is provided by mathematical complexity. However, it could potentially be threatened by paradigm shifts in computing technology. Encryption techniques using quantum key distribution based on entangled photons would allow for theoretical full secure communication. The very same platform, entangled photons, can also be employed as a core element to establish multi-node secure communication---a concept known as quantum network. For these reasons, entangled photon sources might be the core of future quantum networks for secure communication. In this thesis, I study GaAs/AlGaAs quantum dots as entangled photon sources. After giving a general overview on the fundamentals of photonic quantum networks and GaAs droplet-etched quantum dots, I mainly focus on two aspects of the development of this technology. First, limits of the source performance as entangled photon sources and second, applications of entangled photons from quantum dots for secure communication. The prior includes degrading effects of entanglement in these quantum dots, especially based on multiphoton emission and optical Stark effect induced by the particular entangled-photon generation technique, resonant two-photon excitation. The experimental results demonstrate that multiphoton emission is negligible under practical conditions, which is supported by a probabilistic model. The finite excitation laser pulse duration in resonant two-photon excitation, on the other hand, induces an optical Stark effect. The measurements in this thesis support the theoretical predictions and an entanglement reduction by increasing excitation laser pulse length is observed experimentally. If some conditions are met, GaAs/AlGaAs quantum dots emit highly entangled photons, which are utilized in the second part of this thesis by applying them in entanglement-based quantum key distribution protocols. The demonstrations range from the first implementation of quantum dots as entangled photon sources for secure communication in fiber and free-space, to a continuous secret key exchange over three days. The second test case, in particular, tackles the challenges of real-life applications such as sunlight and mild rain. At the end, I provide a brief outlook on how to use entangled photons from GaAs/AlGaAs quantum dots to transfer information from one node of a network, namely a quantum repeater, to another by proposing an experiment called remote quantum teleportation.

Produzione scientifica

11573/1692850 - 2023 - Signatures of the Optical Stark Effect on Entangled Photon Pairs from Resonantly Pumped Quantum Dots
Basso Basset, F; Rota, M B; Beccaceci, M; Krieger, T M; Buchinger, Q; Neuwirth, J; Huet, H; Stroj, S; Covre Da Silva, S F; Ronco, G; Schimpf, C; Höfling, S; Huber-Loyola, T; Rastelli, A; Trotta, R - 01a Articolo in rivista
rivista: PHYSICAL REVIEW LETTERS (American Institute of Physics:2 Huntington Quadrangle, Suite 1NO1:Melville, NY 11747:(800)344-6902, (631)576-2287, EMAIL: subs@aip.org, INTERNET: http://www.aip.org, Fax: (516)349-9704) pp. 166901- - issn: 0031-9007 - wos: (0) - scopus: 2-s2.0-85175709466 (0)

11573/1670849 - 2023 - Daylight entanglement-based quantum key distribution with a quantum dot source
Basso Basset, F; Valeri, M; Neuwirth, J; Polino, E; Rota, M; Poderini, D; Pardo, C; Rodari, G; Roccia, E; Da Silva, Sfc; Ronco, G; Spagnolo, N; Rastelli, A; Carvacho, G; Sciarrino, F; Trotta, R - 01a Articolo in rivista
rivista: QUANTUM SCIENCE AND TECHNOLOGY (Bristol : IOP Publishing) pp. - - issn: 2058-9565 - wos: WOS:000916501500001 (9) - scopus: 2-s2.0-85146661696 (8)

11573/1646279 - 2022 - Quantum violation of local causality in an urban network using hybrid photonic technologies
Carvacho, Gonzalo; Roccia, Emanuele; Valeri, Mauro; Basset, Francesco Basso; Poderini, Davide; Pardo, Claudio; Polino, Emanuele; Carosini, Lorenzo; Rota, Michele B.; Neuwirth, Julia; Covre Da Silva, Saimon F.; Rastelli, Armando; Spagnolo, Nicolò; Chaves, Rafael; Trotta, Rinaldo; Sciarrino, Fabio - 01a Articolo in rivista
rivista: OPTICA (Washington, DC: Optical Society of America, 2014-) pp. 572-578 - issn: 2334-2536 - wos: WOS:000799613700018 (6) - scopus: 2-s2.0-85134702585 (8)

11573/1672151 - 2022 - Multipair Emission Effects in Quantum Dot-based Entangled Photon Sources
Neuwirth, J.; Basso Basset, F.; Rota, Michele; Da Silva, S. C.; Jons, K. D.; Rastelli, A.; Trotta, R. - 04b Atto di convegno in volume
congresso: SPIE Nanoscience + Engineering, 2022 (San Diego, California, United States)
libro: Proceedings Volume 12206, Quantum Nanophotonic Materials, Devices, and Systems 2022 - (9781510653962; 9781510653979)

11573/1672144 - 2022 - Multipair-free source of entangled photons in the solid state
Neuwirth, Julia; Basso Basset, Francesco; Rota, Michele B.; Hartel, Jan-Gabriel; Sartison, Marc; Covre Da Silva, Saimon F.; J??Ns, Klaus D.; Rastelli, Armando; Trotta, Rinaldo - 01a Articolo in rivista
rivista: PHYSICAL REVIEW. B (Ridge NY: American Physical Society, [2016-]) pp. - - issn: 2469-9950 - wos: WOS:000901738900006 (2) - scopus: 2-s2.0-85143677084 (3)

11573/1540874 - 2021 - Quantum key distribution with entangled photons generated on demand by a quantum dot
Basso Basset, F.; Valeri, M.; Roccia, E.; Muredda, V.; Poderini, D.; Neuwirth, J.; Spagnolo, N.; Rota, M. B.; Carvacho Vera, G.; Sciarrino, F.; Trotta, R. - 01a Articolo in rivista
rivista: SCIENCE ADVANCES (Washington, DC : American Association for the Advancement of Science, 2015-) pp. - - issn: 2375-2548 - wos: WOS:000633443000020 (74) - scopus: 2-s2.0-85103230653 (69)

11573/1617005 - 2021 - Quantum dot technology for quantum repeaters: from entangled photon generation toward the integration with quantum memories
Neuwirth, Julia; Basso Basset, Francesco; Rota, Michele B; Roccia, Emanuele; Schimpf, Christian; Jöns, Klaus D; Rastelli, Armando; Trotta, Rinaldo - 01a Articolo in rivista
rivista: MATERIALS FOR QUANTUM TECHNOLOGY ([Bristol]: IOP Publishing, 2021-) pp. 043001- - issn: 2633-4356 - wos: WOS:001084797900001 (9) - scopus: 2-s2.0-85128175518 (13)

11573/1417285 - 2019 - Gold Nanoislands Grown on Multiphoton Polymerized Structures as Substrate for Enzymatic Reactions
Buchegger, Bianca; Vidal, Cynthia; Neuwirth, Julia; Buchroithner, Boris; Karner, Andreas; Hochreiner, Armin; Klar, Thomas A.; Jacak, Jaroslaw - 01a Articolo in rivista
rivista: ACS MATERIALS LETTERS (Washington DC: American Chemical Society, [2019]-) pp. 399-403 - issn: 2639-4979 - wos: WOS:000519825400003 (5) - scopus: 2-s2.0-85083734086 (5)

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