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dc.contributor.advisorSkaar, Johannesnb_NO
dc.contributor.advisorMakarov, Vadimnb_NO
dc.contributor.authorBugge, Audun Nystadnb_NO
dc.date.accessioned2014-12-19T13:28:05Z
dc.date.available2014-12-19T13:28:05Z
dc.date.created2014-01-27nb_NO
dc.date.issued2012nb_NO
dc.identifier691459nb_NO
dc.identifierntnudaim:6826nb_NO
dc.identifier.urihttp://hdl.handle.net/11250/249457
dc.description.abstractQuantum cryptography has been developed from being a theoretical proposal to having real world applications, with companies developing and selling quantum key distribution (QKD) instruments commercially. Although laws of quantum physics guarantee perfect security in the key distribution protocol, several vulnerabilities in the practical implementations have been described and demonstrated. In some of these attacks the eavesdropper has been able to acquire the entire secret key without being detected by the two communicating parties.This thesis describes an experimental setup for automatically characterizing and damaging single photon avalanche photodiodes using a high power laser to damage the diode with the intention to find new weaknesses in QKD systems. Hopefully, the discovery of loopholes will stimulate the researchers and commercial manufacturers to fix their implementations, leading to more secure systems.For a silicon avalanche photodiode (APD) in a passive-quenching circuit, a number of interesting results have been found. It has been shown that we are able to change many of the APDs key characteristics by applying strong illumination.We have been able to reduce the dark count rate of several APDs by up to 80% in a predictable way by strong laser illumination, an effect which is believed to be caused by localized annealing. This is an interesting result not only in the field of quantum cryptography, but perhaps also for improving the manufacturing process of different semiconductor components.Other parameters that have been found to change in interesting ways are the dark current and the breakdown voltage. It has been demonstrated that these changes may compromise the security of QKD systems.nb_NO
dc.languageengnb_NO
dc.publisherInstitutt for elektronikk og telekommunikasjonnb_NO
dc.titleControlled Laser Damage of Single-Photon Avalanche Photodiodesnb_NO
dc.typeMaster thesisnb_NO
dc.source.pagenumber77nb_NO
dc.contributor.departmentNorges teknisk-naturvitenskapelige universitet, Fakultet for naturvitenskap og teknologi, Institutt for materialteknologinb_NO


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