{"id":239301,"date":"2026-06-19T02:23:44","date_gmt":"2026-06-19T07:23:44","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2026\/06\/out-of-equilibrium-cesium-atoms-reveal-fractional-fermi-seas-exposing-new-critical-quantum-phase"},"modified":"2026-06-19T02:23:44","modified_gmt":"2026-06-19T07:23:44","slug":"out-of-equilibrium-cesium-atoms-reveal-fractional-fermi-seas-exposing-new-critical-quantum-phase","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2026\/06\/out-of-equilibrium-cesium-atoms-reveal-fractional-fermi-seas-exposing-new-critical-quantum-phase","title":{"rendered":"Out-of-equilibrium cesium atoms reveal fractional Fermi seas, exposing new critical quantum phase"},"content":{"rendered":"<p><a class=\"aligncenter blog-photo\" href=\"https:\/\/lifeboat.com\/blog.images\/out-of-equilibrium-cesium-atoms-reveal-fractional-fermi-seas-exposing-new-critical-quantum-phase.jpg\"><\/a><\/p>\n<p>In a new study <a href=\"https:\/\/doi.org\/10.1103\/j3s5-gjpf\" target=\"_blank\">published<\/a> in <i>Physical Review Letters<\/i>, a team from the N\u00e4gerl group, together with theory collaborator Alvise Bastianello from the CNRS and the Universit\u00e9 Paris-Dauphine, demonstrates that highly unusual quantum states known as \u201cfractional Fermi seas\u201d can be quantum engineered.<\/p>\n<p>By driving quantum particles\u2014here, ultracold cesium atoms under one-dimensional confinement\u2014far out of equilibrium through cyclic changes of the particle interaction, a novel critical phase of matter emerges, going beyond what is known from the celebrated <a href=\"https:\/\/phys.org\/news\/2024-05-condensation-ground-state-cesium-atoms.html?utm_source=embeddings&utm_medium=related&utm_campaign=internal\" rel=\"related\">Tomonaga-Luttinger liquid theory<\/a>. The new publication serves as the theoretical companion to, and foundation for, recent experimental work in the group of Hanns-Christoph N\u00e4gerl at the Department of Experimental Physics.<\/p>\n<p>Usually, particles in the quantum world follow strict rules about how they organize themselves at low temperatures. As Bastianello explains, \u201cFermions, for instance, stack neatly into the available energy states to form the so-called \u2018Fermi sea.\u2019 But what happens if one forces interacting atoms to continuously cycle through extreme conditions, smoothly shifting them from strongly repelling each other to strongly attracting each other?\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In a new study published in Physical Review Letters, a team from the N\u00e4gerl group, together with theory collaborator Alvise Bastianello from the CNRS and the Universit\u00e9 Paris-Dauphine, demonstrates that highly unusual quantum states known as \u201cfractional Fermi seas\u201d can be quantum engineered. By driving quantum particles\u2014here, ultracold cesium atoms under one-dimensional confinement\u2014far out of [\u2026]<\/p>\n","protected":false},"author":427,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48,1617],"tags":[],"class_list":["post-239301","post","type-post","status-publish","format-standard","hentry","category-particle-physics","category-quantum-physics"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/239301","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/427"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=239301"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/239301\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=239301"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=239301"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=239301"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}