Are nuclear clocks more accurate than atomic clocks? Not yet. A nuclear clock based on thorium-229 has promising properties and has reached important experimental milestones, but it has not demonstrated better accuracy or stability than the leading atomic clocks. Atomic clocks already underpin timekeeping and support navigation, telecommunications, and precision science; nuclear clocks remain a research technology with possible future applications.
How is a nuclear clock different from an atomic clock?
Both kinds of clocks keep time by measuring a repeatable frequency, but they would measure different transitions. An atomic clock interrogates a change in the energy state of an atom’s electrons. A nuclear clock would interrogate a change between energy states inside an atom’s nucleus.
Thorium-229 is the leading nuclear-clock candidate because its unusually low-energy nuclear transition can be driven with ultraviolet light. The transition is expected, in principle, to be less affected by many external disturbances than an electronic transition. That potential advantage does not by itself make a working clock: the transition must be measured and controlled by a complete apparatus, and environmental effects on that apparatus still matter. NIST’s 2024 account of the thorium-229 milestone describes key technology for a future clock, not a fully developed one.
What do accuracy and stability mean?
Accuracy describes how closely a clock’s measured frequency realizes the ideal frequency. Systematic uncertainty estimates uncertainty from known effects that can shift the measured frequency, such as external fields.
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- Atomic Clock Digital - The clock has a built-in receiver that automatically synchronizes itself with WWVB radio broadcast, which will set and update time automatically every midnight, no need to set manually. It has four time zones selectable: EST, PST, MST, CST.
- Digital Wall Clock Battery Operated - This digital clock is supported by 3xAAA battery (Not included). No wires make it can be placed anywhere; and the low battery symbol reminds you to replace the battery in time to avoid getting the wrong time due to low power.
- Digital Wall Clock Large Display - The LCD screen measures 6.2 in x 3.7 in and it displays time, indoor temperature, day and date. Each section is showed separately, allows you to read the content easily and quickly.
- Atomic Clock with Auto DST - With DST on, the time would go forward or backward one hour automatically in daylight saving time, no worry about time changing on that day. If for no need, it could also be turned off, then “AUTO DST” disappears from screen.
- Digital Alarm Clock - The alarm could be turned on or off according to your need, just click the button to set. When alarm is set on, there is a bell icon staying on screen. The icon will disappear if alarm is set off. When alarm goes off, just click any button to stop it on the day.
Stability describes statistical fluctuations in the measured frequency and how much those fluctuations shrink as measurements are averaged over time. A clock can be very stable while still having comparatively large systematic uncertainty. A fair comparison therefore needs to specify whether it is reporting accuracy, stability, or both, and the conditions and averaging time for the measurement. NIST’s 2025 aluminum-ion clock report distinguishes these kinds of performance measures.
Are nuclear clocks more accurate than atomic clocks?
No demonstrated result establishes that today. The strongest numerical results in the available evidence are from optical atomic clocks, not nuclear clocks. In 2025, NIST reported a systematic uncertainty of 5.5×10−19 for its aluminum-ion optical clock, describing it as 41% more accurate than the previous record and 2.6 times more stable than any other ion clock. Those comparisons refer to atomic-clock performance.
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- Atomic Wall Clock Never Need Setting: Atomic clock has a built-in receiver that automatically synchronizes itself with the WWVB radio broadcast by the US Government's National Institute (NIST) in Fort Collins, Colorado. The Atomic Clock will always be accurate to within one second as it receives daily WWVB updates. (No Backlight)
- Atomic Clock with Indoor/Outdoor Temp: The Wireless outdoor sensor transmits the outdoor temperature to the atomic clock. The sensor should be placed within 100ft of the clock. Also, clock has a built-in high-quality indoor temperature sensor so that you can read the temperature both indoor and outdoor
- Digital Wall Clock Large Display: Jumbo 2.5 inch Height Time Digital Display - Use as either a wall clock or as a desk clock, it is easy to read, easy to Use and easy to set up. This atomic clock has been designed with absolute simplicity in mind, you can also set it manually. Excellent clocks for seniors, suitable for anyplace in your home or office
- Atomic Clock Digital: 12/24 Hour time formats with accurate and clear second minute and hour display; 4 time zone to choose (PST, MST, CST, EST); auto daylight saving time; temperature display units in Celsius or Fahrenheit
- Digital Wall Clock Battery Operated: Both clock and outdoor sensor are supported by batteries only, no need to plug or charge (Batteries not included). The existed alarm features can wake you up in the morning or help you keep track of dates and days of the week to avoid missing any important meetings or appointments
A JILA/NIST strontium optical lattice clock reported a systematic uncertainty of 8×10−19 in 2024 and demonstrated sensitivity to relativistic time shifts over submillimeter scales. These results show why leading atomic clocks are a demanding benchmark. Neither figure is a nuclear-clock measurement, and the evidence does not provide a directly comparable measured nuclear-clock accuracy or stability value. NIST’s aluminum-ion report and its JILA/NIST strontium-clock report describe the respective atomic-clock results.
Do nuclear clocks work yet?
Research teams have demonstrated important pieces of the technology, but not a nuclear clock that beats leading atomic clocks. In 2024, a JILA-led team measured the thorium-229 nuclear transition using a specialized ultraviolet laser and an optical frequency comb, and linked the measured frequency directly to a strontium atomic clock. NIST called this a key step toward a nuclear clock while noting that it was not yet a complete clock.
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- [Automatic Time Updates] – The Atomic Time Feature conveniently allows the clock to sync with the WWVB radio transmission from Fort Collins, CO, for accurate time updates.
- [Classic design] – With unmatched attention to detail, the WT-3129B is highlighted by a distinctive matted 12-inch black frame with a silver bezel – a statement piece for any home setting.
- [5-Year Battery Life] – A quality set of 3 “AA” batteries will keep the clock running for up to 5 years – an impressive feat offering unparalleled convenience and peace of mind.
- [SIMPLE-SET] Simple adjustable switch to your Time Zone (4 different selections: PT-Pacific, MT-Mountain, CT-Central, ET-Eastern)
- [A Brand You Can Trust] – Family-owned and operated since 1983, La Crosse Technology is the world leader in Atomic Time and Weather Instruments. Designed in La Crosse, WI, our products have unmatched support resources, including printed setup guides, helpful video tutorials, and lifetime access to our USA-based tech support team.
NIST’s nuclear-clock explainer reports that research groups in Europe and China locked continuous-wave lasers to the thorium nuclear resonant frequency in 2026. It also says these experiments still lag state-of-the-art optical clocks and cesium fountain clocks, and that a nuclear clock surpassing the best optical clocks remains years away. Two challenges help explain the gap:
- Ultraviolet laser performance: the laser technology needs further improvement to support the precision the clock requires.
- Crystal-induced shifts: a solid crystal can hold many thorium nuclei and may help stability, but crystal-lattice fields can shift the nuclear transition and complicate accuracy. Trapping thorium atoms or holding them in optical lattices is one proposed way to reduce this problem.
These are distinct milestones: observing and measuring a nuclear transition, locking a laser to it, and operating a complete clock with superior performance are not interchangeable claims. NIST’s current nuclear-clock explainer describes the 2026 progress and remaining limits.
Rank #4
- Atomic Clock with Backlight: Never Need Setting, a built-in receiver that automatically synchronizes itself with the WWVB radio broadcast, it will always be accurate to within one second as it receives daily WWVB updates. Three levels (OFF-LOW-HIGH) backlight helps you to know what time it is without turning the light on late at night
- Large Digital Wall Clock: 14 inches large display with 4.3 inches numbers make this digital wall clock easy to read and it's visible around the entire room, friendly to the elderly and the visually impaired
- Digital Wall Clock Battery Operated: The clock is supported by four AA battery (not included). No wires make it can be placed anywhere; and the low battery symbol reminds you to replace the battery in time to avoid getting the wrong time due to low power
- Digital Clock with Date and Day of the Week: This digital wall clock with backlight not only does it give you the time, you can also get the day, date and current indoor temp at just a glance. And the day and temp display could be chosen to display alone or in turns every 10s
- Multiple Display Formats: Large digital wall clock with backlight makes it easy to know the time, two different time and temperature formats (12/24H; /) are available for your convenience and preference
What are atomic clocks used for today?
Atomic clocks are established tools, not just laboratory concepts. The SI second is defined using the cesium-133 transition: one second is the duration of exactly 9,192,631,770 cycles of radiation corresponding to that transition. Atomic clocks also support timekeeping, navigation, and telecommunications, while optical clocks enable precision tests of relativity, geodesy, and fundamental physics. NIST’s explanation of the second gives the formal definition.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What might nuclear clocks be used for?
Potential applications are prospective, not current deployments. NIST identifies precision metrology and fundamental-physics research—including tests involving ultralight dark matter and the strong nuclear force—as motivations for nuclear clocks. National time scales, navigation satellites, deep-space navigation, and compact, robust clocks are also possible future roles. Their feasibility depends on building a clock whose performance, size, and operating requirements suit those tasks; the demonstrated research milestones do not yet establish such systems. See NIST’s overview of nuclear-clock prospects and challenges.
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- SIGNATURE READABILITY & ATOMIC PRECISION: See the time clearly from across the room with bold custom numerals, ultra-white contrast, and a large 14" face. Daily atomic syncing keeps time accurate automatically with no drifting. Designed for instant visibility in homes, offices, schools, and shared spaces. For use in the lower 48 states only. Not recommended for Hawaii, Alaska, or international use
- SELF-SETTING, ZERO HASSLE: Insert the included AA battery, select the time zone, set daylight savings, and press reset. The clock automatically syncs to the official U.S. atomic signal from Fort Collins, Colorado and keeps precise time year-round with no manual adjustments. Not for use in Alaska or Hawaii
- PREMIUM MATERIALS, INDOOR OR OUTDOOR: Glass lens, satin-finish dial, durable black frame, and weather-resistant rear battery cover support dependable indoor or covered outdoor use. Suitable for kitchens, patios, porches, garages, break rooms, pool houses, and classrooms
- LARGE SPACE VISIBILITY & EVERYDAY USE: Suitable for living rooms, kitchens, offices, schools, lecture halls, factories, gyms, and covered outdoor areas. Easy across-room readability helps families, professionals, students, and seniors stay confidently on time
- BOLD DESIGN ELEMENTS: Features large black numerals on a crisp white face inspired by highway signage, a bold red second hand, and premium glass lens that deliver clear visibility from any angle and complement various decor styles including modern, Scandinavian, industrial, or traditional
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