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<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">najo</journal-id><journal-title-group><journal-title xml:lang="en">Nanosystems: Physics, Chemistry, Mathematics</journal-title><trans-title-group xml:lang="ru"><trans-title>Наносистемы: физика, химия, математика</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">2220-8054</issn><issn pub-type="epub">2305-7971</issn><publisher><publisher-name>Университет ИТМО</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.17586/2220-8054-2026-17-4-415-423</article-id><article-id custom-type="elpub" pub-id-type="custom">najo-1903</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>MATHEMATICS</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>МАТЕМАТИКА</subject></subj-group></article-categories><title-group><article-title>On eigenvalues of the discrete Schrödinger operator on a ladder of a d-dimensional square lattice</article-title><trans-title-group xml:lang="ru"><trans-title>О собственных значениях дискретного оператора Шрёдингера на лестнице d-мерной квадратной решётки</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Муминов</surname><given-names>М. И.</given-names></name><name name-style="western" xml:lang="en"><surname>Muminov</surname><given-names>M. I.</given-names></name></name-alternatives><bio xml:lang="en"><p>Mukhiddin I. Muminov </p><p>University blv., 15, Samarkand, 140104; Tashkent, 100174</p><p> </p></bio><email xlink:type="simple">mmuminov@mail.ru</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Садуллаева</surname><given-names>М. С.</given-names></name><name name-style="western" xml:lang="en"><surname>Sadullaeva</surname><given-names>M. S.</given-names></name></name-alternatives><bio xml:lang="en"><p>Maftuna S. Sadullaeva</p><p>Yasmin street, 11, Samarkand, 140100 </p></bio><email xlink:type="simple">bmaftunasadullaeva03@gmail.com</email><xref ref-type="aff" rid="aff-2"/></contrib></contrib-group><aff xml:lang="en" id="aff-1"><institution>Samarkand State University; &#13;
V.I. Romanovskiy Institute of Mathematics, Uzbekistan Academy of Sciences</institution><country>Uzbekistan</country></aff><aff xml:lang="en" id="aff-2"><institution>Samarkand State Pedagogical institute</institution><country>Uzbekistan</country></aff><pub-date pub-type="collection"><year>2026</year></pub-date><pub-date pub-type="epub"><day>31</day><month>08</month><year>2026</year></pub-date><volume>17</volume><issue>4</issue><fpage>415</fpage><lpage>423</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Muminov M.I., Sadullaeva M.S., 2026</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="ru">Муминов М.И., Садуллаева М.С.</copyright-holder><copyright-holder xml:lang="en">Muminov M.I., Sadullaeva M.S.</copyright-holder><license xml:lang="ru" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>Данная работа распространяется под лицензией Creative Commons Attribution 4.0.</license-p></license><license xml:lang="en" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://nanojournal.ifmo.ru/jour/article/view/1903">https://nanojournal.ifmo.ru/jour/article/view/1903</self-uri><abstract><p>We consider a discrete Schrödinger operator H on a ladder of d-dimensional square lattices with a self-adjoint matrix-valued potential whose entries are the scalars λ and µ. We investigate conditions for the existence of eigenvalues and describe their exact locations in terms of the parameters λ and µ for the cases d = 1 and d = 2.</p></abstract><trans-abstract xml:lang="ru"><p>Рассматривается дискретный оператор Шрёдингера H на лестнице d-мерных квадратных решёток с самосопряжённым матричнозначным потенциалом, элементами которого являются скаляры λ и μ. Исследуются условия существования собственных значений и описывается их точное расположение в зависимости от параметров λ и μ для случаев d=1 и d=2.</p><p> </p></trans-abstract><kwd-group xml:lang="ru"><kwd>дискретный оператор Шрёдингера</kwd><kwd>собственные значения</kwd><kwd>дискретный спектр</kwd></kwd-group><kwd-group xml:lang="en"><kwd>discrete Schrödinger operator</kwd><kwd>eigenvalue</kwd><kwd>discrete spectrum</kwd></kwd-group><funding-group><funding-statement xml:lang="en">We would like to thank the anonymous reviewers for their constructive comments that have greatly contributed to improving the manuscript. The work was supported by the Fundamental Science Foundation of Uzbekistan, Grant No. AL9224104685.</funding-statement></funding-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Shi H., Barnard A.S., Snook I.K. 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