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In high-speed decoy-state QKD systems, however, intensity correlations between succeeding pulses leak information about the users' intensity settings, thus invalidating a key assumption of this approach. Here, we solve this pressing problem by developing a general technique to incorporate arbitrary intensity correlations to the security analysis of decoy-state QKD. This technique only requires to experimentally quantify two main parameters: the correlation range and the maximum relative deviation between the selected and the actually emitted intensities. As a side contribution, we provide a non-standard derivation of the asymptotic secret key rate formula from the non-asymptotic one, in so revealing a necessary condition for the significance of the former.<\/jats:p>","DOI":"10.22331\/q-2021-12-07-602","type":"journal-article","created":{"date-parts":[[2021,12,7]],"date-time":"2021-12-07T15:01:35Z","timestamp":1638889295000},"page":"602","update-policy":"https:\/\/doi.org\/10.22331\/q-crossmark-policy-page","source":"Crossref","is-referenced-by-count":38,"title":["Security of quantum key distribution with intensity correlations"],"prefix":"10.22331","volume":"5","author":[{"given":"V\u00edctor","family":"Zapatero","sequence":"first","affiliation":[{"name":"Escuela de Ingenier\u00eda de Telecomunicaci\u00f3n, Department of Signal Theory and Communications, \u00adUniversity of Vigo, Vigo E-36310, Spain"}]},{"given":"\u00c1lvaro","family":"Navarrete","sequence":"additional","affiliation":[{"name":"Escuela de Ingenier\u00eda de Telecomunicaci\u00f3n, Department of Signal Theory and Communications, \u00adUniversity of Vigo, Vigo E-36310, Spain"}]},{"given":"Kiyoshi","family":"Tamaki","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan"}]},{"given":"Marcos","family":"Curty","sequence":"additional","affiliation":[{"name":"Escuela de Ingenier\u00eda de Telecomunicaci\u00f3n, Department of Signal Theory and Communications, \u00adUniversity of Vigo, Vigo E-36310, Spain"}]}],"member":"9598","published-online":{"date-parts":[[2021,12,7]]},"reference":[{"key":"0","doi-asserted-by":"publisher","unstructured":"Scarani, V. et al. 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