{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,14]],"date-time":"2026-05-14T05:09:28Z","timestamp":1778735368544,"version":"3.51.4"},"reference-count":43,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,4,27]],"date-time":"2026-04-27T00:00:00Z","timestamp":1777248000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Passive state preparation\u2013continuous variable quantum key distribution (PSP-CVQKD) protocol inherits the advantage of high secret key rate (SKR) of CVQKD, while overcoming the drawback of complex modulation equipment in GMCS-CVQKD. In recent years, it has received extensive attention in the experimental field. Even so, short transmission distance remains its prominent issue. In this paper, a scheme for introducing non-Gaussian operations into PSP-CVQKD in optical fiber links is proposed. We derive the input\u2013output relationship of the system, as well as the calculation formulas for the success probability and SKR, when non-Gaussian operations are introduced at both sides of the channels respectively. The results indicate that the improved PSP-CVQKD scheme is feasible in enhancing the SKR performance and can effectively increase the transmission distance. Our scheme provides beneficial ideas for further in-depth research on non-Gaussian operations and the performance improvement of other PSP-CVQKD protocols.<\/jats:p>","DOI":"10.3390\/e28050497","type":"journal-article","created":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T07:43:51Z","timestamp":1777448631000},"page":"497","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Improved Passive State Preparation\u2013Continuous Variable Quantum Key Distribution Scheme Based on Non-Gaussian Operations"],"prefix":"10.3390","volume":"28","author":[{"given":"Hao","family":"Luo","sequence":"first","affiliation":[{"name":"School of Automation, Central South University, Changsha 410083, China"},{"name":"School of Information Engineering, Gannan University of Science and Technology, Ganzhou 341000, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yijun","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Automation, Central South University, Changsha 410083, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5019-7209","authenticated-orcid":false,"given":"Hang","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Automation, Central South University, Changsha 410083, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiajia","family":"Zhong","sequence":"additional","affiliation":[{"name":"State Grid Jiangxi Ganzhou Power Supply Company, Ganzhou 341000, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,27]]},"reference":[{"key":"ref_1","first-page":"172","article-title":"The actual content of quantum theoretical kinematics and mechanics","volume":"43","author":"Heisenberg","year":"1983","journal-title":"Zhurnal Phys."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"802","DOI":"10.1038\/299802a0","article-title":"A single quantum cannot be cloned","volume":"299","author":"Wootters","year":"1982","journal-title":"Nature"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"062337","DOI":"10.1103\/PhysRevA.92.062337","article-title":"Unidimensional continuous-variable quantum key distribution","volume":"92","author":"Usenko","year":"2015","journal-title":"Phys. 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