The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Nuclear clocks are difficult to build because the promising thorium-229 nuclear transition is hard to excite and measure with the precision a clock requires. A crystal can provide a strong signal from many nuclei, but its lattice shifts and broadens the resonance; trapped ions avoid that host-material problem but face different systematic errors. As of NIST’s August 2026 overview, reported thorium-clock experiments still trail leading optical and cesium clocks.
Why use thorium-229 for a nuclear clock?
Most nuclear transitions require far more energetic radiation than ordinary lasers can provide. Thorium-229 is unusual: its low-energy isomeric transition can be reached with vacuum-ultraviolet (VUV) light, making laser spectroscopy practical in a way it is not for most nuclei. The transition’s high frequency and the relative insensitivity of nuclear states to some environmental effects make it an attractive clock reference, though neither feature makes it immune to disturbance. The 2024 review of the thorium-229 isomer describes the long effort to locate and measure this rare transition.
The challenge is not simply finding the transition. A clock needs to excite it reproducibly, determine its frequency precisely, and account for shifts caused by the apparatus and the thorium’s surroundings.
What makes a thorium nuclear clock difficult to build?
Producing and stabilizing suitable VUV light
The laser must reach the nuclear resonance, deliver enough useful light to excite it, and maintain the narrow spectral linewidth and low phase noise needed for precision interrogation. VUV laser sources are technically demanding; NIST says their efficiency and performance still need substantial improvement compared with the capabilities available at more familiar visible wavelengths. A laser that is too weak or spectrally noisy limits how effectively researchers can drive and measure the transition. (NIST’s August 2026 overview; 2024 review)
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Getting the resonance frequency right has itself been a measurement challenge. The energy estimate changed as measurement methods improved, and the transition’s spectral location shaped the choice of detection and excitation techniques. Older estimates should not be treated as the definitive current value; the relevant point for clock construction is that the target must be identified and addressed with demanding VUV instrumentation. (2024 review)
Getting enough signal without introducing a worse environment
A trapped ion can be controlled individually, but one or a few nuclei produce a relatively small signal. A thorium-doped solid crystal contains a large ensemble, improving signal-to-noise and offering a route to a compact, potentially room-temperature device. But nuclei in a crystal do not all experience exactly the same local fields. Those variations can broaden the ensemble resonance, while the host lattice can shift its frequency. Researchers therefore face a central trade-off: a stronger collective signal from many nuclei versus cleaner isolation of the clock transition. (2024 review; NIST)
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Correcting environmental frequency shifts
A clock can produce a steady signal yet report the wrong frequency if its surroundings shift the resonance. In solid hosts, electromagnetic interactions with the lattice and temperature-dependent effects must be characterized and controlled. The 2024 review identifies magnetic-dipole and second-order Doppler effects as contributors to inhomogeneous broadening, and temperature-dependent electric monopole and quadrupole interactions and second-order Doppler shifts among possible global shifts. In a trapped-ion design, excess micromotion and gravity-related shifts are among the systematics instead. No architecture eliminates every source of error. (2024 review)
Turning a resonance into a working clock reference
To operate as a clock, a laser must be locked to the nuclear resonance and its optical frequency measured or counted. In 2024, a JILA-led team demonstrated key elements using thorium-229 embedded in a solid crystal, ultraviolet laser excitation and an optical frequency comb; it also directly compared the transition frequency with a strontium atomic clock. NIST described this as a laboratory demonstration, not a fully developed clock. (NIST, September 4, 2024)
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
How do the clock designs trade off different errors?
| Approach | What it offers | What limits it |
|---|---|---|
| Thorium-doped solid crystal | Many nuclei contribute to the signal, improving signal-to-noise and potential stability; compact, room-temperature operation is a possible practical advantage. | Lattice electric and magnetic interactions can shift or broaden the resonance. Temperature effects, host-material uniformity and reproducibility between samples also matter. |
| Trapped thorium ions | Individual nuclei can be isolated from a crystal host, avoiding host-lattice perturbations. | Trap micromotion and gravity-related shifts contribute systematic uncertainty. VUV laser power, linewidth and phase noise remain important constraints. |
| Established optical clocks | They provide mature high-performance benchmarks and comparison standards. | They use electronic transitions and have their own systematic shifts. The thorium-clock experiments described by NIST have not surpassed their demonstrated performance. |
Useful comparisons require more than asking whether a clock is “nuclear” or “atomic.” Researchers need to consider frequency instability over a stated averaging time, absolute frequency accuracy and its uncertainty budget, transition linewidth and coherence, laser capability, environmental sensitivity, signal strength, sample reproducibility and operational complexity. (2024 review; NIST)
Has a nuclear clock been built, and how well does it perform?
Researchers have demonstrated important components and locked lasers to the thorium resonance, but the cited work does not establish that a thorium nuclear clock outperforms existing leading standards. NIST’s August 2026 overview reports that groups in Europe and China had locked continuous-wave lasers to the resonance, while stating that experimental accuracy and precision still lag state-of-the-art optical clocks and cesium fountains. NIST identifies VUV laser performance and isolation from crystal-lattice fields as continuing challenges. (NIST, page created August 21, 2026)
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Two kinds of reported figures illustrate why performance claims need careful labels:
| Reported figure | What it describes | What it does not establish |
|---|---|---|
| Fractional frequency instability of 3 × 10−12/√(τ/s), approaching 10−15 over one day of continuous operation | The authors’ June 2026 arXiv preprint reports this instability for a thorium-229 optical nuclear clock with a feedback loop. | Instability describes frequency fluctuations over an averaging interval; it is not a measurement proving superior absolute accuracy. The cited result is a preprint, not evidence here of a peer-reviewed result. (June 2026 arXiv preprint) |
| 1.5 × 10−19 projected total uncertainty | The 2024 review reports this as an uncertainty budget estimated in a theoretical analysis for a proposed trapped-ion nuclear clock. | It is a design projection, not achieved experimental accuracy. The same review gives 9.5 × 10−19 as the total systematic frequency uncertainty of the then-best optical atomic clocks it discusses; that is a review-era benchmark, not a current measurement of thorium-clock performance. (2024 review) |
Instability and accuracy answer different questions. Instability describes how much the measured frequency fluctuates as observations are averaged; accuracy concerns how close the corrected result is to the true reference frequency, with uncertainty assigned to that result. Environmental shifts can bias a stable clock, so a favorable instability figure alone is not enough to establish accuracy.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
What would show that a nuclear clock is becoming competitive?
A convincing comparison needs a documented uncertainty budget and reproducible measurements, not just a striking projected number or short-term stability result. The relevant evidence includes:
- Frequency instability reported against a clearly stated averaging time and operating conditions.
- Absolute frequency accuracy with systematic corrections and uncertainties accounted for.
- A sufficiently capable VUV source, including its power, linewidth and phase-noise performance.
- Measurements showing how strongly the result changes with host material, temperature or trap conditions.
- Reproducibility across samples or repeated operation, alongside a practical account of apparatus complexity.
For now, the nuclear transition is a promising precision-measurement candidate, not a proven replacement for optical or cesium clocks. Its progress depends on improving VUV laser systems and controlling the distinct environmental shifts of each architecture; applications such as navigation or tests of fundamental physics remain potential uses rather than demonstrated consumer capabilities.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
