{"id":29684,"date":"2025-10-15T10:56:27","date_gmt":"2025-10-15T05:11:27","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=29684"},"modified":"2025-10-15T10:56:38","modified_gmt":"2025-10-15T05:11:38","slug":"mit-physicists-improve-the-precision-of-atomic-clocks","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/mit-physicists-improve-the-precision-of-atomic-clocks\/","title":{"rendered":"MIT physicists improve the precision of atomic clocks\u00a0"},"content":{"rendered":"\n
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Credit: Ryley McConkey<\/sup><\/em><\/figcaption><\/figure>\n\n\n\n

Every time you check the time on your phone, make an online transaction, or use a navigation app, you are depending on the precision of atomic clocks.<\/p>\n\n\n\n

An atomic clock keeps time by relying on the \u201cticks\u201d of atoms as they naturally oscillate at rock-steady frequencies. Today\u2019s atomic clocks operate by tracking cesium atoms, which tick over 10 billion times per second. Each of those ticks is precisely tracked using lasers that oscillate in sync, at microwave frequencies. <\/p>\n\n\n\n

Scientists are developing next-generation atomic clocks that rely on even faster-ticking atoms such as ytterbium, which can be tracked with lasers at higher, optical frequencies. If they can be kept stable, optical atomic clocks could track even finer intervals of time, up to 100 trillion times per second. <\/p>\n\n\n\n

Now, MIT physicists have found a way to improve the stability of optical atomic clocks, by reducing \u201cquantum noise\u201d \u2014 a fundamental measurement limitation due to the effects of quantum mechanics, which obscures the atoms\u2019 pure oscillations. In addition, the team discovered that an effect of a clock\u2019s laser on the atoms, previously considered irrelevant, can be used to further stabilize the laser. <\/p>\n\n\n\n

The researchers developed a method to harness a laser-induced \u201cglobal phase\u201d in ytterbium atoms, and have boosted this effect with a quantum-amplification technique. The new approach doubles the precision of an optical atomic clock, enabling it to discern twice as many ticks per second compared to the same setup without the new method. What\u2019s more, they anticipate that the precision of the method should increase steadily with the number of atoms in an atomic clock. <\/p>\n\n\n\n

The researchers detail the method, which they call global phase spectroscopy, in a study appearing in the journal Nature<\/em><\/a>.<\/em>They envision that the clock-stabilizing technique could one day enable portable optical atomic clocks that can be transported to various locations to measure all manner of phenomena. <\/p>\n\n\n\n

\u201cWith these clocks, people are trying to detect dark matter and dark energy, and test whether there really are just four fundamental forces<\/a>, and even to see if these clocks can predict earthquakes,\u201d says study author Vladan Vuleti\u0107, the Lester Wolfe Professor of Physics at MIT. \u201cWe think our method can help make these clocks transportable and deployable to where they\u2019re needed.\u201d<\/p>\n\n\n\n

The paper\u2019s co-authors are Leon Zaporski, Qi Liu, Gustavo Velez, Matthew Radzihovsky, Zeyang Li, Simone Colombo, and Edwin Pedrozo-Pe\u00f1afiel, who are members of the MIT-Harvard Center for Ultracold Atoms and the MIT Research Laboratory of Electronics.<\/p>\n\n\n\n

Ticking time<\/strong><\/p>\n\n\n\n

In 2020, Vuleti\u0107 and his colleagues demonstrated that an atomic clock could be made more precise<\/a> by quantumly entangling the clock\u2019s atoms. Quantum entanglement is a phenomenon by which particles can be made to behave in a collective, highly correlated manner. When atoms are quantumly entangled, they redistribute any noise, or uncertainty in measuring the atoms\u2019 oscillations, in a way that reveals a clearer, more measurable \u201ctick.\u201d <\/p>\n\n\n\n

In their previous work, the team induced quantum entanglement among several hundred ytterbium atoms that they first cooled and trapped in a cavity formed by two curved mirrors. They sent a laser into the cavity, which bounced thousands of times between the mirrors, interacting with the atoms and causing the ensemble to entangle. They were able to show that quantum entanglement could improve the precision of existing atomic clocks by essentially reducing the noise, or uncertainty between the laser\u2019s and atoms\u2019 tick rates. <\/p>\n\n\n\n

At the time, however, they were limited by the ticking instability of the clock\u2019s laser. In 2022, the same team derived a way to further amplify the difference in laser versus atom tick rates<\/a> with \u201ctime reversal\u201d \u2014 a trick that relies on entangling and de-entangling the atoms to boost the signal acquired in between. <\/p>\n\n\n\n

However, in that work the team was still using traditional microwaves, which oscillate at much lower frequencies than the optical frequency standards ytterbium atoms can provide. It was as if they had painstakingly lifted a film of dust off a painting, only to then photograph it with a low-resolution camera.<\/p>\n\n\n\n

\u201cWhen you have atoms that tick 100 trillion times per second, that\u2019s 10,000 times faster than the frequency of microwaves,<\/s>\u201d Vuleti\u0107 says. \u201cWe didn\u2019t know at the time how to apply these methods to higher-frequency optical clocks that are much harder to keep stable.\u201d <\/p>\n\n\n\n

About phase<\/strong><\/p>\n\n\n\n

In their new study, the team has found a way to apply their previously developed approach of time reversal to optical atomic clocks. They then sent in a laser that oscillates near the optical frequency of the entangled atoms. <\/p>\n\n\n\n

\u201cThe laser ultimately inherits the ticking of the atoms,\u201d says first author Zaporski. \u201cBut in order for this inheritance to hold for a long time, the laser has to be quite stable.\u201d<\/p>\n\n\n\n

The researchers found they were able to improve the stability of an optical atomic clock by taking advantage of a phenomenon that scientists had assumed was inconsequential to the operation. They realized that when light is sent through entangled atoms, the interaction can cause the atoms to jump up in energy, then settle back down into their original energy state and still carry the memory about their round trip.<\/p>\n\n\n\n

\u201cOne might think we\u2019ve done nothing,\u201d Vuleti\u0107 says. \u201cYou get this global phase of the atoms, which is usually considered irrelevant. But this global phase contains information about the laser frequency.\u201d<\/p>\n\n\n\n

In other words, they realized that the laser was inducing a measurable change in the atoms, despite bringing them back to the original energy state, and that the magnitude of this change depends on the laser\u2019s frequency. <\/p>\n\n\n\n

\u201cUltimately, we are looking for the difference of laser frequency and the atomic transition frequency,\u201d explains co-author Liu. \u201cWhen that difference is small, it gets drowned by quantum noise. Our method amplifies this difference above this quantum noise.\u201d<\/p>\n\n\n\n

In their experiments, the team applied this new approach and found that through entanglement they were able to double the precision of their optical atomic clock.<\/p>\n\n\n\n

\u201cWe saw that we can now resolve nearly twice as small a difference in the optical frequency or, the clock ticking frequency, without running into the quantum noise limit,\u201d Zaporski says. \u201cAlthough it\u2019s a hard problem in general to run atomic clocks, the technical benefits of our method it will make it easier, and we think this can enable stable, transportable atomic clocks.\u201d <\/p>\n\n\n\n

This research was supported, in part, by the U.S. Office of Naval Research, the National Science Foundation, the U.S. Defense Advanced Research Projects Agency, the U.S. Department of Energy, the U.S. Office of Science, the National Quantum Information Science Research Centers, and the Quantum Systems Accelerator.<\/p>\n","protected":false},"excerpt":{"rendered":"

Every time you check the time on your phone, make an online transaction, or use a navigation app, you are depending on the precision of atomic clocks.<\/p>\n","protected":false},"author":2,"featured_media":29685,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[121],"tags":[],"class_list":["post-29684","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-physics"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0.webp",900,600,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-200x200.webp",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-675x450.webp",675,450,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-768x512.webp",750,500,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0.webp",750,500,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0.webp",900,600,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0.webp",900,600,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0.webp",900,600,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-870x570.webp",870,570,true],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-600x600.webp",600,600,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-600x600.webp",600,600,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-760x490.webp",760,490,true],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-550x360.webp",550,360,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-95x65.webp",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-640x600.webp",640,600,true],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-96x96.webp",96,96,true],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/10\/MIT-Atomic-Clocks-01-press_0-150x100.webp",150,100,true]},"author_info":{"info":["RevoScience"]},"category_info":"Physics<\/a>","tag_info":"Physics","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/29684","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=29684"}],"version-history":[{"count":2,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/29684\/revisions"}],"predecessor-version":[{"id":29687,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/29684\/revisions\/29687"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/29685"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=29684"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=29684"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=29684"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}