{"id":1877,"date":"2025-02-18T09:58:19","date_gmt":"2025-02-18T09:58:19","guid":{"rendered":"https:\/\/www.cns.s.u-tokyo.ac.jp\/wp-homepage\/?page_id=1877"},"modified":"2025-04-23T05:48:52","modified_gmt":"2025-04-23T05:48:52","slug":"fundamental_physics","status":"publish","type":"page","link":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/research\/fundamental_physics\/","title":{"rendered":"Fundamental Symmetry"},"content":{"rendered":"<div class=\"wp-block-cover\" style=\"margin-top:0;margin-bottom:0;padding-top:0;padding-bottom:0;min-height:314px;aspect-ratio:unset;\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" class=\"wp-block-cover__image-background wp-image-3994 size-large\" alt=\"\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-1024x768.jpg\" data-object-fit=\"cover\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-1024x768.jpg 1024w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-300x225.jpg 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-768x576.jpg 768w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-1536x1152.jpg 1536w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-2048x1536.jpg 2048w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/laser-16x12.jpg 16w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><span aria-hidden=\"true\" class=\"wp-block-cover__background has-background-dim\" style=\"background-color:#031f4d\"><\/span><div class=\"wp-block-cover__inner-container has-global-padding is-layout-constrained wp-block-cover-is-layout-constrained\">\n<p class=\"has-text-align-center animated fadeIn delay-200ms has-base-2-color has-text-color has-link-color has-xx-large-font-size wp-elements-9e77e37dda8ea1916d473530de8c6971\" style=\"font-style:normal;font-weight:900\">Fundamental Symmetry<\/p>\n<\/div><\/div>\n\n\n\n<div class=\"wp-block-group alignfull has-global-padding is-layout-constrained wp-block-group-is-layout-constrained\">\n<div style=\"height:24px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\">\n<h3 class=\"wp-block-heading\">Exploring New Physics with Quantum Precise Spectroscopy on Ultracold Heavy Atoms<\/h3>\n\n\n\n<p>We aim to unravel the origin of matters in the early universe\u2014including the mechanism behind the disappearance of antimatter and the nature of dark matter\u2014from the perspective of breakings in fundamental symmetries.\nIn heavy atomic nuclei with extreme structures, relativistic effects and nuclear deformation significantly amplify subtle symmetry violations. These nuclei thus serve as powerful microscopes for probing fundamental symmetries.<br>\nBy producing such heavy elements via nuclear reactions and applying laser cooling techniques to precisely control their quantum states, we conduct high-precision quantum measurements using atomic interferometers.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Search for the permanent electric dipole moment (EDM) using optical lattice-based atomic interferometry<\/li>\n\n\n\n<li>Anapole moment experiments to probe weak interactions inside the nuclear medium<\/li>\n\n\n\n<li>Development of hybrid-atom comagnetometers for highly sensitive magnetic field measurements<\/li>\n<\/ul>\n\n\n\n<p>are the ongoing projects.<\/p>\n\n\n\n<p><a href=\"https:\/\/fundamental-symmetry.cns.s.u-tokyo.ac.jp\/\" data-type=\"link\" data-id=\"https:\/\/fundamental-symmetry.cns.s.u-tokyo.ac.jp\/\">Sakemi Lab. Webpage<\/a><\/p>\n<\/div>\n\n\n\n<div style=\"height:60px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\">\n<h3 class=\"wp-block-heading\">Francium and Its Production<\/h3>\n\n\n\n<p>Among heavy atoms, the main target of our group is Francium (Fr). Fr is the 87th element in the periodic table and is the heaviest alkali element discovered as of April 2025, which encourage the functionality as a microscope.<\/p>\n\n\n\n<p>Unlike more familiar alkali metals such as lithium (Li), sodium (Na), and potassium (K), francium has no stable isotopes. Therefore, it cannot be obtained in sufficient quantities from natural sources and must instead be artificially produced using an accelerator.<br>At the Fundamental Symmetry Group, we are developing an experimental setup to generate Fr atoms at the RIKEN accelerator facility and trap them in a vacuum using laser light.<\/p>\n\n\n\n<p class=\" translation-block\">Although several methods for producing Fr are known, we use a highly efficient method suitable for small-scale domestic accelerators. In this method, an ion beam of oxygen (O) is directed at a gold (Au) target to induce <strong>a nuclear fusion reaction<\/strong>.<br>\nUsing an accelerator called the AVF cyclotron, the O beam is accelerated to approximately 100 MeV (about 10,000 km\/s, roughly 3% the speed of light) and bombarded onto the Au target. As a result, the compound nucleus Fr-215 is formed at a rate of about 0.001%.<br>\nThe produced Fr atoms diffuse through the solid Au target when it is heated close to its melting point (about 1000\u202f\u00b0C), and after around 100 seconds, they reach the surface and eventually desorb as ions. By applying a positive voltage to the Au target, the ions can be extracted as a francium ion beam (Figure 2-1).<\/p>\n\n\n\n<p class=\" translation-block\">To realize this mechanism, we developed a <strong>surface ionization ion source<\/strong> (Figure 1-1) in 2019. In the following year's experiment, we achieved a francium ion beam of Fr-210 at a record domestic intensity of 6.7\u00d710\u2076 ions per second (Figure 1-3).<\/p>\n\n\n\n<div class=\"wp-block-group has-background is-vertical is-layout-flex wp-container-core-group-is-layout-97eb2d20 wp-block-group-is-layout-flex\" style=\"border-radius:12px;background-color:#eef2f6;padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-medium\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"226\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-001-300x226.png\" alt=\"\" class=\"wp-image-4147\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-001-300x226.png 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-001-16x12.png 16w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-001.png 412w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n\n\n\n<p>Fgure 1-1. Vacuum chamber of the surface ionization ion source.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-medium\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"224\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-002-300x224.png\" alt=\"\" class=\"wp-image-4148\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-002-300x224.png 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-002-16x12.png 16w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-002.png 410w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n\n\n\n<p>Figure 1-2. Gold target (the golden disc at the center) and the \"takefune\" electrode (the arc-shaped, folding screen-like structure) used to shape the ion beam.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-medium\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"213\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-003-300x213.png\" alt=\"\" class=\"wp-image-4149\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-003-300x213.png 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-003-18x12.png 18w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-003.png 304w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n\n\n\n<p>Figure 1-3. Result of counting alpha particles emitted from a metal plate irradiated with the ion beam extracted from the surface ionization ion source, categorized by particle energy. A distinct peak appears near 6500 keV, which is attributed to Fr.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p class=\" translation-block\">To convert the produced ions into neutral atoms and capture them, we use a neutralizer that facilitates charge exchange with a metal surface, as well as a magneto-optical trap (MOT).\nThese components are assembled and connected to the accelerator beamline to carry out the experiments (Figure 1-4).\nUnlike nuclear scattering experiments, our experiments deal with extremely low energy scales, such as ion beams with energies around 10 eV and atoms cooled to temperatures of several hundred microkelvin (\u03bcK).\nMoreover, unlike typical cold atom experiments, all apparatus must be operated in a radiation environment. Additionally, since Fr atoms can only be used during beam time, experimental optimization must be carried out using other atomic species. We are addressing these challenges by applying our ideas and continuously refining them through trial and error..<\/p>\n\n\n\n<div class=\"wp-block-group has-background is-vertical is-layout-flex wp-container-core-group-is-layout-97eb2d20 wp-block-group-is-layout-flex\" style=\"border-radius:12px;background-color:#eef2f6;padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:50%\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"535\" height=\"402\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-009.png\" alt=\"\" class=\"wp-image-4222\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-009.png 535w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-009-300x225.png 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-009-16x12.png 16w\" sizes=\"auto, (max-width: 535px) 100vw, 535px\" \/><\/figure>\n\n\n\n<p>Figure 1-4.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:50%\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:60px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\">\n<h3 class=\"wp-block-heading\">Laser cooling of atoms<\/h3>\n\n\n\n<p class=\" translation-block\">One of the laser cooling techniques we employ is <strong>Doppler cooling<\/strong>. As illustrated in Figure 2-1, laser light with a frequency slightly lower than the atomic resonance is used.<br>\nWhen an atom absorbs a photon, it is excited and receives the photon's momentum, causing it to decelerate.<br>\nAfter a short time, the atom spontaneously emits a photon and returns to its ground state. Although the atom receives a recoil from this emission, the direction of spontaneous emission is random, and thus the recoil momentum averages out to zero over time.<br>\nBy repeating this absorption\u2013emission cycle tens of thousands of times, atoms moving at room temperature speeds (~300\u202fm\/s) can be slowed to just a few meters per second.<br>\nWhen counter-propagating lasers are applied along three orthogonal axes, atoms can be cooled in all three spatial directions.<br>\nAdditionally, a magneto-optical trap (MOT) that combines this laser cooling with a magnetic field gradient created by anti-Helmholtz coils allows atoms to be spatially confined at temperatures of several hundred microkelvin (\u03bcK).<br>\nFigure 2-2 shows a fluorescence image of Rb atoms cooled to around 100\u202f\u03bcK, captured with a camera.<\/p>\n\n\n\n<div class=\"wp-block-group has-background is-vertical is-layout-flex wp-container-core-group-is-layout-9ae43232 wp-block-group-is-layout-flex\" style=\"border-radius:12px;background-color:#eef2f6;padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:70%\">\n<div class=\"wp-block-group wp-container-content-e29552f7 is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"2560\" height=\"1034\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-scaled.png\" alt=\"\" class=\"wp-image-4165\" style=\"object-fit:cover\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-scaled.png 2560w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-300x121.png 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-1024x414.png 1024w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-768x310.png 768w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-1536x620.png 1536w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-2048x827.png 2048w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-005-18x7.png 18w\" sizes=\"auto, (max-width: 2560px) 100vw, 2560px\" \/><\/figure>\n\n\n\n<p>Figure 2-1.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:30%\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-medium\"><img loading=\"lazy\" decoding=\"async\" width=\"225\" height=\"300\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-225x300.jpg\" alt=\"\" class=\"wp-image-4166\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-225x300.jpg 225w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-770x1024.jpg 770w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-768x1022.jpg 768w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-1154x1536.jpg 1154w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-1539x2048.jpg 1539w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006-9x12.jpg 9w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-006.jpg 1860w\" sizes=\"auto, (max-width: 225px) 100vw, 225px\" \/><\/figure>\n\n\n\n<p>Figure 2-2.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p>Francium (Fr) has no stable isotopes and, as mentioned above, must be produced via nuclear fusion reactions using an accelerator. As a result, experiments involving Fr atoms can only be conducted during the limited periods when the accelerator is in operation.<br>To prepare for precision Fr-EDM (Electric Dipole Moment) measurements, we are conducting research and development using stable alkali atoms such as rubidium (Rb) and cesium (Cs) in our laser spectroscopy laboratory.<\/p>\n\n\n\n<p>To perform laser cooling and precision spectroscopy of atoms, it is essential to prepare lasers tuned to the specific energy levels of each atomic species and to stabilize their frequencies. Accordingly, we have developed lasers matched to the transition frequencies of Rb, Cs, and Fr respectiveley, and constructed spectroscopy systems and electronic circuits that employ absorption lines in gas cells for feedback control. These narrow-linewidth lasers are operated on a daily basis (Fig. 2-3).<\/p>\n\n\n\n<div class=\"wp-block-group has-background is-vertical is-layout-flex wp-container-core-group-is-layout-9ae43232 wp-block-group-is-layout-flex\" style=\"border-radius:12px;background-color:#eef2f6;padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:50%\">\n<div class=\"wp-block-group wp-container-content-e29552f7 is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-1024x768.jpeg\" alt=\"\" class=\"wp-image-4419\" style=\"object-fit:cover\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-1024x768.jpeg 1024w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-300x225.jpeg 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-768x576.jpeg 768w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-1536x1152.jpeg 1536w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-2048x1536.jpeg 2048w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-010-16x12.jpeg 16w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>\u56f32-3.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:30%\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:45px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\">\n<h3 class=\"wp-block-heading\">Optical Lattice Co-Magnetometer<\/h3>\n\n\n\n<p class=\" translation-block\">For precision atomic spectroscopy, however, the near-resonant lasers used for Doppler cooling can disturb the quantum states of atoms.<br>\nTo address this, atoms are transferred into an optical lattice\u2014a potential formed by standing waves of far-off-resonant laser light.<br>\nThe atoms interact with the electric field of the non-resonant laser, causing an energy shift known as the Stark shift.<br>\nThe stronger the electric field, the lower the atomic energy levels, causing atoms to be trapped in the intensity maxima (antinodes) of the standing wave.<\/p>\n\n\n\n<p class=\" translation-block\">When francium atoms are cooled below the Doppler limit and trapped in such an optical lattice, they become powerful probes for investigating violations of fundamental symmetries in nature.<br>\nThis is because relativistic effects and nuclear deformation\u2014particularly pronounced in heavy atoms like Fr\u2014can greatly enhance symmetry-violating signals. This enhancement is often likened to a \"<strong>microscope<\/strong>\" for fundamental symmetry violations (Figure 3-1). However, this microscopic sensitivity also makes the system extremely susceptible to external perturbations such as magnetic and optical fields. It is therefore essential to detect and correct for these disturbances. This leads to the concept of the optical lattice co-magnetometer (Figure 3-2). In this approach, lighter atoms, which do not significantly amplify symmetry violations, are also trapped in the same optical lattice.<br>\nIn 2024, we successfully trapped Rb and Cs simultaneously in the same optical lattice.\nUsing spin precession frequency measurements based on the Faraday rotation effect\u2014a method known for enabling quantum non-demolition  measurements\u2014we were able to simultaneously extract both magnetic and optical fields.\nWe are currently working to further improve measurement precision and are also <strong>exploring novel techniques that utilize unique quantum phenomena<\/strong>.<\/p>\n\n\n\n<div class=\"wp-block-group has-background is-vertical is-nowrap is-layout-flex wp-container-core-group-is-layout-9db03c03 wp-block-group-is-layout-flex\" style=\"border-radius:12px;background-color:#eef2f6;padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"439\" height=\"326\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-007.png\" alt=\"\" class=\"wp-image-4168\" style=\"width:375px\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-007.png 439w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-007-300x223.png 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-007-16x12.png 16w\" sizes=\"auto, (max-width: 439px) 100vw, 439px\" \/><\/figure>\n\n\n\n<p>\u56f3 3-1.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1925\" height=\"2112\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008.png\" alt=\"\" class=\"wp-image-4169\" style=\"width:355px;height:auto\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008.png 1925w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008-273x300.png 273w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008-933x1024.png 933w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008-768x843.png 768w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008-1400x1536.png 1400w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008-1867x2048.png 1867w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/fund-phys-img-008-11x12.png 11w\" sizes=\"auto, (max-width: 1925px) 100vw, 1925px\" \/><\/figure>\n\n\n\n<p>\u56f3 3-2.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p class=\" translation-block\">Laser cooling experiments are a type of tabletop experiment, and due to their relatively small scale, individual ideas and creativity play a major role in driving the research forward.\nThe laser sources, electronic circuits, and vacuum systems used in this study are all designed and developed in-house, <strong>making it especially rewarding to conduct experiments using equipment we have built ourselves<\/strong>.<\/p>\n<\/div>\n\n\n\n<div style=\"height:51px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\">\n<h3 class=\"wp-block-heading translation-block\">Development of Another Isotope: <sup>221<\/sup>Fr<\/h3>\n\n\n\n<p class=\" translation-block\">Fr-221 is an unstable isotope with a half-life of approximately 5 minutes, produced via alpha decay of Ac-225.\nBecause Ac-225 itself has a half-life of about 10 days and continuously emits Fr-221 over an extended period, experiments using Fr-221 can be conducted over several weeks without the need for an accelerator\u2014unlike with Fr-210.<\/p>\n\n\n\n<p class=\" translation-block\">Moreover, unlike Fr-210, Fr-221 has a half-integer nuclear spin, which allows its nucleus to exhibit an electric dipole moment (EDM) originating from quarks.<br>\nBy performing measurements with both Fr-210 and Fr-221 in parallel, there is potential to probe the <strong>electric dipole moment of the quarks<\/strong>.<\/p>\n\n\n\n<p>We are currently developing techniques for the trapping and cooling of Fr-221 in preparation for high-precision spectroscopic measurements (Figure 4-1).<\/p>\n\n\n\n<div class=\"wp-block-group has-background is-vertical is-layout-flex wp-container-core-group-is-layout-9ae43232 wp-block-group-is-layout-flex\" style=\"border-radius:12px;background-color:#eef2f6;padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"2560\" height=\"1920\" src=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-scaled.jpg\" alt=\"\" class=\"wp-image-3995\" style=\"width:375px\" srcset=\"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-scaled.jpg 2560w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-300x225.jpg 300w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-1024x768.jpg 1024w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-768x576.jpg 768w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-1536x1152.jpg 1536w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-2048x1536.jpg 2048w, https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/wp-content\/uploads\/2025\/04\/hotlab-16x12.jpg 16w\" sizes=\"auto, (max-width: 2560px) 100vw, 2560px\" \/><\/figure>\n\n\n\n<p>Figure 4-1. Development of Laser cooling of Fr-221<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>\u51b7\u5374\u91cd\u5143\u7d20\u3092\u7528\u3044\u305f\u91cf\u5b50\u7cbe\u5bc6\u6e2c\u5b9a\u3067\u62d3\u304f\u65b0\u3057\u3044\u7269\u7406 \u53cd\u7269\u8cea\u6d88\u5931\u6a5f\u69cb\u3001\u6697\u9ed2\u7269\u8cea\u306e\u5b9f\u4f53\u306a\u3069\u3001\u5b87\u5b99\u592a\u53e4\u306e\u7269\u8cea\u5275\u6210\u306e\u6b74\u53f2\u3092 [&hellip;]<\/p>","protected":false},"author":1,"featured_media":0,"parent":1640,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"wp-custom-template-v1-2","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-1877","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/pages\/1877","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/comments?post=1877"}],"version-history":[{"count":67,"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/pages\/1877\/revisions"}],"predecessor-version":[{"id":4435,"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/pages\/1877\/revisions\/4435"}],"up":[{"embeddable":true,"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/pages\/1640"}],"wp:attachment":[{"href":"https:\/\/www.cns.s.u-tokyo.ac.jp\/cns\/en\/wp-json\/wp\/v2\/media?parent=1877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}