Self-aligned optical microcomb emerging between octave-separated lasers.

September 30, 2026| Source: Nature

Optical frequency combs (OFCs) are frequency rulers essential for precision metrology, next-generation navigation and testing of fundamental physics 1 . Despite intense efforts, chip-integrated OFCs remain laboratory-bound, unable to fulfil their promise of compact and cost-effective deployment. Although improvements in fabrication and integration are important, a conceptual limitation has stymied progress: on-chip OFC architectures have aimed to miniaturize their table-top counterparts and relied on cascading outward from a single pump 2,3 . In integrated platforms, this approach does not readily generate the strong, low-noise, octave-spaced signals crucial for robust zero-frequency offset detection 4 . Here we overcome this limitation through an architectural inversion, in which an optical microcomb fills the spectrum between two octave-separated pumps. The two pumps generate a parametrically driven cavity soliton 5 in an integrated χ (3) resonator 6 , which robustly self-aligns to both pumps across multiple foundry-fabricated devices and operating configurations. This produces a single octave-spanning comb from telecom to visible wavelengths, whose zero-frequency offset is defined by the harmonic offset of the pumps and can therefore be reliably detected and stabilized. We showcase the capabilities of our platform by executing all of the three core tasks of OFC metrology: optical frequency synthesis, low-noise millimetre-wave generation and integrated optical clock readout, using the same self-aligned microcomb with only its input locks changed.

Read the original source →

Extensive glacier loss in the coterminous United States.

Glaciers populate the mountain ranges of the western conterminous United States and despite their importance to alpine hydrology, their area and volume change have never been comprehensively evaluated. Our study shows that since the mid-twentieth century about one-quarter of the glaciers have disappeared and the overall area and volume are reduced by one-third. The pattern of glacier shrinkage suggests most glaciers in the conterminous United States are largely maintained by local topographic in

Physical/TechOctober 20, 2026

Reaction-based cryo-EM resolves the continuous conformational spectrum of CTP synthase catalysis.

Capturing enzymes under native turnover conditions remains a grand challenge in structural biology. Here, we develop a reaction-based cryo-electron microscopy (cryo-EM) strategy that directly samples Drosophila melanogaster cytidine triphosphate synthase (CTPS) from actively catalyzing mixtures containing only natural substrates and allosteric effectors. By integrating reaction-based sampling with three-dimensional variability analysis, we resolve a continuous conformational spectrum of CTPS dur

Physical/TechOctober 20, 2026

GTP orchestrates CTP synthase via an allosteric effector-cycling mechanism.

Cytidine triphosphate (CTP), a fundamental building block of RNA, plays vital roles in diverse biological processes. CTP synthase (CTPS) is the only known enzyme for de novo synthesis of CTP. Efficient CTPS catalysis requires guanosine triphosphate (GTP) in a dose-dependent, nonconsumptive manner; however, the precise mechanism by which GTP drives CTP formation remains unclear. Here, we integrate a series of cryo-EM structures of Drosophila melanogaster CTPS captured from actively catalyzing sam

Physical/TechOctober 20, 2026

Antiferromagnetism and tightly bound Cooper pairs induced by kinetic frustration.

Antiferromagnetism and superconductivity are often viewed as competing orders in correlated electron systems. Here, we demonstrate that kinetic frustration in hole motion facilitates their coexistence within the square-lattice repulsive Hubbard model. Combining exact analytical solutions on tailored geometries with large-scale numerical simulations, we reveal a robust pairing mechanism: Holes on opposite sublattices behave as if they carry opposite effective charges due to spin singlet formation

Physical/TechOctober 20, 2026

Coordinated transformations of the labyrinth and occiput during the dinosaur-bird transition.

Evolutionary shape changes of the vertebrate semicircular canals (SCCs) are often ascribed to evolutionary transitions in locomotion, including the origin of flight during the dinosaur-bird transition. However, the potential for transformations of braincase architecture to influence SCC shape independent of sensory-functional adaptation has generally been overlooked. We evaluate the influence of both factors using a large dataset of 146 living and recently extinct crown birds, including taxa rep