{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T23:34:16Z","timestamp":1790033656228,"version":"4.0.1"},"reference-count":50,"publisher":"American Physical Society (APS)","issue":"4","license":[{"start":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T00:00:00Z","timestamp":1784764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP20H05641"],"award-info":[{"award-number":["JP20H05641"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP21K14551"],"award-info":[{"award-number":["JP21K14551"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP24K01377"],"award-info":[{"award-number":["JP24K01377"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP24H02232"],"award-info":[{"award-number":["JP24H02232"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP24H00400"],"award-info":[{"award-number":["JP24H00400"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.aps.org"],"crossmark-restriction":true},"short-container-title":["Phys. Rev. Lett."],"accepted":{"date-parts":[[2026,6,29]]},"abstract":"<jats:p>\n                    A non-Hermitian point gap (NHPG) is a unique phenomenon in non-Hermitian systems and induces a non-Hermitian skin effect (NHSE). In photonic crystals, NHPG and NHSE have previously been explored mainly through material loss, where the typically low\n                    <a:math xmlns:a=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"inline\">\n                      <a:mrow>\n                        <a:mi>Q<\/a:mi>\n                      <\/a:mrow>\n                    <\/a:math>\n                    factors make direct observation of complex frequencies challenging. Here, we demonstrate the direct experimental observation of an NHPG by using a radiation-loss-based non-Hermitian photonic crystal. Radiation loss can be engineered through structural design, enabling control of the imaginary part of the complex frequency and allowing relatively high\n                    <c:math xmlns:c=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"inline\">\n                      <c:mi>Q<\/c:mi>\n                    <\/c:math>\n                    factors. This approach is compatible with widely used absorption-free silicon-slab photonic crystals. We developed a measurement system that can measure photonic bands along arbitrary lines in\n                    <e:math xmlns:e=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" display=\"inline\">\n                      <e:mi>k<\/e:mi>\n                    <\/e:math>\n                    space. Our measurements showed complex-frequency loops of the NHPG in photonic crystals, and the reversal of non-Hermitian topology through the flip of the loop rotation in a complex plane. These results establish radiation-loss engineering as a practical route to directly measuring and controlling complex photonic band structures and bulk point-gap topology in nanophotonic systems without gain media or nonreciprocity.\n                  <\/jats:p>","DOI":"10.1103\/vsx1-17cl","type":"journal-article","created":{"date-parts":[[2026,6,29]],"date-time":"2026-06-29T14:43:19Z","timestamp":1782744199000},"update-policy":"https:\/\/doi.org\/10.1103\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Observation of Radiation-Loss-Based Non-Hermitian Point Gap in Photonic Crystals"],"prefix":"10.1103","volume":"137","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9089-0363","authenticated-orcid":true,"given":"Yuto","family":"Moritake","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/05dqf9946","id-type":"ROR","asserted-by":"publisher"}],"name":"Institute of Science 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All rights are reserved, including those for text and data mining, AI training, and similar technologies.","name":"copyright_statement","label":"Copyright statement","group":{"name":"copyright","label":"copyright"}},{"value":"2026","name":"copyright_year","label":"Copyright year","group":{"name":"copyright","label":"copyright"}},{"value":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/","name":"creative_commons_license","label":"Creative Commons license","group":{"name":"licenses","label":"Licenses"}},{"value":"\u00a92026 The authors","name":"copyright_holder","label":"Copyright holder","group":{"name":"copyright","label":"copyright"}}],"article-number":"046903"}}