{"id":47620,"date":"2025-07-10T21:25:09","date_gmt":"2025-07-10T15:55:09","guid":{"rendered":"https:\/\/www.nextias.com\/ca\/?p=47620"},"modified":"2025-07-21T15:32:45","modified_gmt":"2025-07-21T10:02:45","slug":"optical-atomic-clock","status":"publish","type":"post","link":"https:\/\/www.nextias.com\/ca\/current-affairs\/10-07-2025\/optical-atomic-clock","title":{"rendered":"Optical Atomic Clock\u00a0"},"content":{"rendered":"\n<p><strong>Syllabus: GS3\/ Science and Technology<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Context<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Researchers from six countries have conducted the<strong> world\u2019s largest and most accurate comparison of optical atomic clocks<\/strong> across three continents.&nbsp;<\/li>\n\n\n\n<li>It is a major step towards redefining the <strong>SI unit of time \u2014 the second<\/strong> \u2014 using optical clocks instead of current caesium-based atomic clocks.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>What is the Current Definition of a Second?<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Present Standard (since 1967):<\/strong> One second equals the time taken for <strong>9,192,631,770 cycles<\/strong> of radiation produced by the <strong>caesium-133<\/strong> atom when it changes between two energy states.\n<ul class=\"wp-block-list\">\n<li>Caesium was chosen for its high accuracy and consistency.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>India\u2019s Timekeeping:<\/strong> The <strong>National Physical Laboratory (NPL)<\/strong> in Delhi maintains India\u2019s time standard using five caesium clocks.\n<ul class=\"wp-block-list\">\n<li>The clocks\u2019 output is disseminated to various applications around India via the INSAT satellites, telecommunication signals, and fibre links.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>What are Optical Atomic Clocks?<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Like caesium clocks, <strong>Optical Atomic Clocks measure time<\/strong> based on an atom\u2019s internal energy transitions, but <strong>use optical (visible light) frequencies<\/strong> instead of microwaves.<\/li>\n\n\n\n<li><strong>Common Atoms Used in Optical Clocks:<\/strong> Strontium-87 (Sr), Ytterbium-171 (Yb) and Ytterbium ions (Yb\u207a), Indium-115 ions (In\u207a) and Charged Strontium-88 (Sr\u207a).<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Why Replace Caesium with Optical Clocks?<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Higher Frequency, Better Precision:<\/strong> Optical clocks use higher-frequency visible light, enabling more oscillations per second and thus more precise time measurement than caesium clocks.\n<ul class=\"wp-block-list\">\n<li><strong>Caesium<\/strong> clocks use radiation at <strong>9.19 billion Hz,<\/strong><\/li>\n\n\n\n<li><strong>Strontium<\/strong> clocks use<strong> 429 trillion Hz,<\/strong><\/li>\n\n\n\n<li><strong>Ytterbium<\/strong> clocks use <strong>642 trillion Hz.<\/strong><\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Unmatched Stability: <\/strong>Some optical clocks are so stable that they drift by just one second in <strong>15 billion years<\/strong>, making them <strong>10,000 times more precise<\/strong> than caesium clocks.<\/li>\n\n\n\n<li><strong>Atomic Transition Principle : <\/strong>Like caesium clocks, optical clocks measure time by counting how atoms shift between fixed energy levels.\n<ul class=\"wp-block-list\">\n<li>But instead of microwaves, they use lasers to stimulate and detect these shifts, resulting in much more stable and accurate frequency measurements.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Significance of the Development<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Lays Foundation<\/strong> for Redefining the Second, likely by<strong> 2030.<\/strong><\/li>\n\n\n\n<li><strong>Supports High-Precision <\/strong>Applications like:\n<ul class=\"wp-block-list\">\n<li><strong>Satellite navigation<\/strong> (GPS, NavIC, Galileo)<\/li>\n\n\n\n<li><strong>Radio astronomy<\/strong> (e.g., black hole imaging)<\/li>\n\n\n\n<li><strong>Climate science<\/strong> (tracking gravity changes due to ice\/water loss)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p><strong>Source: <\/strong><a href=\"https:\/\/www.thehindu.com\/sci-tech\/science\/intercontinental-optical-clock-comparison-sets-stage-to-redefine-the-second\/article69787042.ece\" rel=\"nofollow noopener\" target=\"_blank\"><strong>TH<\/strong><\/a><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<h3><strong>Context<\/strong><\/h3>\n<li class=\"ms-5\">Researchers from six countries have conducted the world\u2019s largest and most accurate comparison of optical atomic clocks across three continents.\u00a0<\/li>\n<p><\/p>\n<h3><strong>What is the Current Definition of a Second?<\/strong><\/h3>\n<li class=\"ms-5\">Present Standard (since 1967): One second equals the time taken for 9,192,631,770 cycles of radiation produced by the caesium-133 atom when it changes between two energy states.<\/li>\n<li class=\"ms-5\">Caesium was chosen for its high accuracy and consistency.<\/li>\n<li class=\"ms-5\">India\u2019s Timekeeping: The National Physical Laboratory (NPL) in Delhi maintains India\u2019s time standard using five caesium clocks.<\/li>\n<li class=\"ms-5\">The clocks\u2019 output is disseminated to various applications around India via the INSAT satellites, telecommunication signals, and fibre links.<\/li>\n<p><a href=\"https:\/\/www.nextias.com\/ca\/current-affairs\/10-07-2025\/optical-atomic-clock\" class=\"btn btn-primary btn-sm float-end\">Read\u00a0More<\/a><\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[21],"tags":[],"class_list":["post-47620","post","type-post","status-publish","format-standard","hentry","category-current-affairs"],"acf":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/47620","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/comments?post=47620"}],"version-history":[{"count":4,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/47620\/revisions"}],"predecessor-version":[{"id":48756,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/47620\/revisions\/48756"}],"wp:attachment":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/media?parent=47620"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/categories?post=47620"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/tags?post=47620"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}