TY - BOOK ED - Bacsárdi, László ED - Kovács, Kálmán TI - Proceedings of the 8th International Conference on Research, Technology and Education of Space PB - Magyar Asztronautikai Társaság C1 - Budapest PY - 2024 SP - 76 SN - 9789637367342 UR - https://m2.mtmt.hu/api/publication/34818857 ID - 34818857 LA - English DB - MTMT ER - TY - JOUR AU - Bacsárdi, László AU - Kis, Zsolt TI - Hazai eredmények a kvantumhálózatok fejlesztésében JF - FIZIKAI SZEMLE J2 - FIZIKAI SZEMLE VL - 74 PY - 2024 IS - 4 SP - 124 EP - 128 PG - 5 SN - 0015-3257 UR - https://m2.mtmt.hu/api/publication/34794507 ID - 34794507 LA - Hungarian DB - MTMT ER - TY - CONF AU - Bacsárdi, László TI - National Space Education with 17 Universities T2 - Winter Satellite Workshop 2024 PY - 2024 SP - 1 EP - 2 PG - 2 UR - https://m2.mtmt.hu/api/publication/34519766 ID - 34519766 LA - English DB - MTMT ER - TY - CONF AU - Ifkovics, Barnabás AU - Bacsárdi, László TI - Analyzing a multi-satellite quantum communication network T2 - 74th International Astronautical Congress, IAC 2023 VL - 2023-October PB - International Astronautical Federation, IAF T3 - Proceedings of the International Astronautical Congress, IAC, ISSN 0074-1795 ; 2023-October. PY - 2023 PG - 9 UR - https://m2.mtmt.hu/api/publication/34763430 ID - 34763430 N1 - Conference code: 197475 Export Date: 2 April 2024 Correspondence Address: Ifkovics, B.; Department of Networked Systems and Services, Műegyetem rkp. 3., Hungary; email: ifkovics.barnabas@gmail.com AB - Quantum-based satellite networks utilize the power of quantum technology to transmit and receive information globally. They are using quantum mechanics to encrypt and decrypt data, thus making it virtually impossible for someone to intercept or hack the communication. Such infrastructure can conduct highly accurate measurements, which can help precision agriculture, medical imaging, and environmental monitoring. In the future, quantum-based satellite networks can enhance distributed computing by interconnecting multiple quantum processors, significantly increasing the available computational power. In our work, we are interested in the effectiveness of different satellite topologies using two quantum key distribution (QKD) methods: prepare-and-measure and entanglement-based, examining networks operating with one, two, and three satellites. After comparing the results, we determine each case's most effective topologies and protocols. In the paper, we compare two different systems: networks using quantum entanglement (untrusted nodes-based concept) with networks using prepare-and-measure QKD (trusted nodes or reliable satellites-based system). These give us a relatively comprehensive picture of the differences between device-dependent and device-independent satellite infrastructures using available technologies. Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved. LA - English DB - MTMT ER - TY - CHAP AU - Solymos, Balázs AU - Nepusz, Tamás AU - Bacsárdi, László ED - Szakál, Anikó TI - Routing the quantum internet in large LEO satellite constellations T2 - IEEE 23rd International Symposium on Computational Intelligence and Informatics (CINTI 2023) : Proceedings PB - IEEE CY - Danvers (MA) SN - 9798350342956 T3 - International Symposium on Computational Intelligence and Informatics, CINTI, ISSN 2380-8586 PY - 2023 SP - 000397 EP - 000402 PG - 6 DO - 10.1109/CINTI59972.2023.10382070 UR - https://m2.mtmt.hu/api/publication/34531269 ID - 34531269 N1 - Conference code: 196335 Export Date: 19 February 2024 Correspondence Address: Solymos, B.; Budapest University of Technology and Economics, Műegyetem rkp. 3, Hungary; email: solymosb@hit.bme.hu Funding details: 2022-2.1.1-NL-2022-00004 Funding details: Magyar Tudományos Akadémia, MTA, BO/00118/20 Funding details: Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, NKFI Funding text 1: The research was supported by the Ministry of Culture and Innovation and the National Research, Development and Innovation Office within the Quantum Information National Laboratory of Hungary (Grant No. 2022-2.1.1-NL-2022-00004). L. Bacsárdi thanks the support of the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences (Grant No. BO/00118/20). AB - Space is a promising medium for quantum communications, boasting potentially better link performance compared to optical fibers. A future quantum internet, therefore, may rely heavily on satellite networks, which present various open networking challenges, one of which is routing, that today lack definitive solutions, sometimes even in the case of classical networks too. Nonetheless, with ever-bigger satellite constellations, this new plane of networking is slowly becoming a reality. To address the problem of dynamically changing links and handle the unique behavior of quantum repeater protocols, we propose a simple method based on a modified variant of the standard A* graph search algorithm. We then simulate a Starlink-like LEO constellation with simplified models for the main steps of quantum repeater protocols to investigate the feasibility of our method and future quantum satellite networks. LA - English DB - MTMT ER - TY - CONF AU - Galambos, Máté AU - Czermann, Márton AU - Jánosi, Gergely AU - Kornis, János AU - Papp, Zsolt AU - Koller, István AU - Holló, Csaba Tamás AU - Sarkadi, Tamás AU - Erdei, Gábor AU - Barócsi, Attila AU - Kis, Zsolt AU - Koppa, Pál AU - Imre, Sándor AU - Bacsárdi, László TI - Report on the First Hungarian Short Range Free Space QKD Link T2 - Proceedings of the 74th International Astronautical Congress (IAC 2023) PB - International Astronautical Federation (IAF) PY - 2023 PG - 8 UR - https://m2.mtmt.hu/api/publication/34519786 ID - 34519786 AB - Here we report on the development of our short-range free space quantum communication system. We have built an entangled photon-pair source, based on wavefront splitting interference. We used commercially available fibre coupling ports to create a few meters long free space channel in the lab. We transmitted one half of an entangled photon-pair between two optical ground stations while the other photon was measured locally. To identify corresponding photons on the transmitter and receiver sides, we have tested multiple time synchronization and correlation peak search methods. We found that Fourier transform based correlation search-although works well in theory-has trouble finding overlap in case of low signal to noise ratio. Start-stop histograms proved feasible under realistic channel conditions, yet require longer data collection, and perform best with a reasonable guess at the propagation delay and time synchronization offset. We successfully verified that the transmission is suitable for quantum cryptography using Bell-test experiments. Our experiences show that loss has little effect on the average outcome of the Bell-test experiment but interferes with polarization correction resulting in greater variability and less consistency. We also examined the effect of optical turbulence induced fading using a heat source and observed that with properly increased integration time the fading has no effect on the Bell-test experiment. Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved. LA - English DB - MTMT ER - TY - BOOK ED - Bacsárdi, László ED - Barta, Veronika ED - Szárnya, Csilla ED - Wesztergom, Viktor TI - Magyar Űrkutatási Fórum 2023 - Válogatott közlemények PB - Magyar Asztronautikai Társaság CY - Budapest PY - 2023 SN - 9789637367335 UR - https://m2.mtmt.hu/api/publication/34494666 ID - 34494666 LA - Hungarian DB - MTMT ER - TY - CHAP AU - Márton, Botond László AU - Kis, Zsolt AU - Bacsárdi, László TI - Testing the First Hungarian CV-QKD System On a Real Optical Line T2 - 2023 International Conference on Software, Telecommunications and Computer Networks (SoftCOM) PB - IEEE CY - Piscataway (NJ) SN - 9798350301076 T3 - International Conference on Software, Telecommunications and Computer Networks (SoftCOM), ISSN 1847-358X PY - 2023 PG - 6 DO - 10.23919/SoftCOM58365.2023.10271613 UR - https://m2.mtmt.hu/api/publication/34157649 ID - 34157649 N1 - Budapest University of Technology and Economics, Department of Networked Systems and Services, Muegyetem rkp. 3, Budapest, H-1111, Hungary Wigner Research Center for Physics, Department of Nonlinear and Quantum Optics, Budapest, Hungary Export Date: 2 November 2023 Correspondence Address: Marton, B.L.; Budapest University of Technology and Economics, Muegyetem rkp. 3, Hungary; email: bmarton@mcl.hu LA - English DB - MTMT ER - TY - CHAP AU - Schranz, Ágoston AU - Gerhátné Udvary, Eszter AU - Matolcsy, Balázs AU - Bacsárdi, László AU - Nagy, András ED - IEEE, . TI - A Portable Ambient Optical Noise Measurement Station T2 - 2023 23rd International Conference on Transparent Optical Networks (ICTON) PB - IEEE CY - Piscataway (NJ) SN - 9798350303032 PY - 2023 SP - 1 EP - 6 PG - 6 DO - 10.1109/ICTON59386.2023.10207414 UR - https://m2.mtmt.hu/api/publication/34091229 ID - 34091229 N1 - Budapest University of Technology and Economics, Faculty of Electrical Engineering and Informatics, Department of Networked Systems and Services, Magyar tudósok körútja 2., Budapest, 1117, Hungary ELKH-BME Information Systems Research Group, Magyar tudósok körútja 2., Budapest, 1117, Hungary ATL Zrt., Csapás utca 12., Budakalász, 2011, Hungary Export Date: 14 September 2023 Correspondence Address: Schranz, Á.; Budapest University of Technology and Economics, Magyar tudósok körútja 2., Hungary; email: aschranz@hit.bme.hu LA - English DB - MTMT ER - TY - JOUR AU - Mihály, András AU - Bacsárdi, László TI - Optical transmittance based store and forward routing in satellite networks JF - INFOCOMMUNICATIONS JOURNAL J2 - INFOCOMM J VL - 15 PY - 2023 IS - 2 SP - 8 EP - 13 PG - 6 SN - 2061-2079 DO - 10.36244/ICJ.2023.2.2 UR - https://m2.mtmt.hu/api/publication/34069895 ID - 34069895 N1 - Funding Agency and Grant Number: Ministry of Culture and Innovation; National Research, Development and Innovation Office within the Quantum Information National Laboratory of Hungary [2022-2.1.1NL-2022-00004]; Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences Funding text: The research was supported by the Ministry of Culture and Innovation and the National Research, Development and Innovation Office within the Quantum Information National Laboratory of Hungary (Grant No. 2022-2.1.1NL-2022-00004). L. Bacsardi thanks the support of the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences. AB - Quantum computing will play a crucial part in our security infrastructure for the coming years. Quantum networks can consist of direct optical fiber or free-space links. With the use of satellite channels, we can create a quantum network with higher coverage than using optical fibers where the distances are limited due to the properties of the fiber. One of the highest drivers of cost for satellite networks, apart from the cost of the technology needed for such systems, are the costs of launching and maintaining said satellites. By minimizing the satellites needed for a well-functioning quantum network, we can decrease said network’s cost, thus enabling a cheaper quantum internet. In this paper, we present an optical transmittance-based routing algorithm with which it is possible to conduct successful quantum entanglement transfer between terrestrial nodes. LA - English DB - MTMT ER -