To make an ultrastable laser beam for applications such as gravitational-wave detectors, the frequency of a beam confined within an optical cavity is locked to the cavity’s resonant frequency. This frequency is determined by the cavity’s length. The stability of the laser beam’s frequency and the quality of the cavity’s resonance depend on the thermal noise of the mirrors that define that length. Dahyeon Lee at JILA and the University of Colorado Boulder and his colleagues have now demonstrated a crystalline mirror coating with superior thermomechanical properties compared to conventional coatings [1]. The new coating could lead to ultrastable cavities for optical clocks and next-generation interferometers.
Recently, mirrors coated with crystalline alloys of gallium arsenide (GaAs) have emerged as promising candidates to replace those with conventional amorphous dielectric coatings. GaAs-coated mirrors have excellent optical qualities and exhibit low thermal noise at room temperature. But previous studies found that these crystalline coatings suffer from additional noise contributions, which undermine their potential usefulness.
The origins of some of those noise contributions remain unclear. Nevertheless, Lee and colleagues have demonstrated that crystalline GaAs-based coatings can still be superior at cryogenic temperatures. The researchers constructed a 6-cm-long cavity bounded by two mirrors made of alternating layers of GaAs and aluminum gallium arsenide on silicon substrates. They used more layers compared to previous experiments, which reduced photon loss. Operating the cavity at 17 K, where the thermal expansion coefficient of the silicon substrate is zero, they achieved a frequency stability of 2.5 × 10−17. This stability is 4 times better than the expected limit for conventional coatings and sets a new record for cavity-stabilized lasers.
A new analysis suggests modern satellite networks could suffer catastrophic collisions within days of losing control during a major solar storm. The phrase “House of Cards” is often associated today with a Netflix political drama, but its original meaning refers to a structure that is inherently
In November 2020, a freak wave appeared, lifting a lone buoy off the coast of British Columbia 17.6 meters (58 feet) high.
A few years later, the four-story wall of water was confirmed to be the most extreme rogue wave ever recorded.
Such an extraordinary event is thought to happen only once every 1,300 years. And if the buoy hadn’t been taken for a ride, we might never have known it had occurred.
Anil Seth explains why our conscious experience is a world we build from the inside out, rather than from the outside in
(Cell Reports 42, 112185; March 28, 2023)
In our article published on March 28, 2023, the representative image for the cGAMP-treated group was inadvertently replaced with that of the control group in STING-KO cells in Figure 7A, resulting in two control panels being displayed. Similarly, the representative image of the control group of WT cells was inadvertently replaced with that of STING-KO cells in Figure S8A, resulting in two control panels of STING-KO cells being displayed. The errors occurred during figure preparation. The authors have carefully re-examined the original data and now provide the corrected version of the figure panels, which accurately present the appropriate control and treated groups.
The errors and their corrections do not affect any of the conclusions reported in the original manuscript. The authors sincerely apologize for any confusion or inconvenience these errors may have caused.
In a historic first for the laboratory, CERN has received $1 billion in private donations to support the development of the Future Circular Collider (FCC).
This philanthropic backing marks a shift in CERN’s 72-year funding history as it seeks to bridge the gap for the project’s estimated $18 billion price tag.
It comes from the Breakthrough Prize Foundation, the Eric and Wendy Schmidt Fund, and billionaire entrepreneurs John Elkann and Xavier Niel. Together, they pledged a combined $1 billion in late December 2025 to jumpstart the project.
