Galaxy Survey Completes Its Map of the Cosmos The DESI Collaboration has finished its five-year survey ahead of schedule, setting the stage for analyses that could reshape our understanding of dark energy.

The largest-ever high-resolution galaxy survey has concluded. The Dark Energy Spectroscopic Instrument (DESI) scanned its last planned region of sky this past Tuesday, having recorded 47 million galaxies and quasars—13 million more objects than projected.

Superconductor Theory Under Cold-Atom Scrutiny Snapshot measurements of cold-atom gases reveal hidden spin correlations that could force an update of some superconductivity theories.

Using a novel quantum gas microscope, researchers have discovered an unexpected anticorrelation between opposite-spin atoms, implying deficiencies in the Bardeen-Cooper-Schrieffer theory of superconductivity.

How Contact Electrification Depends on Particle Size A free-falling video camera enabled researchers to observe a falling cloud of particles and infer the particles’ charges.

When microparticles of the same insulating material collide, how do they become oppositely charged? Although the question remains unresolved, researchers have now uncovered an important clue: surface charge density is independent of particle size.

Reducing Wires in Quantum Computers A wire-sharing protocol can minimize the number of wires in a quantum processor without significantly reducing speed, a new theoretical study shows.

In so-called time multiplexing, one wire controls several qubits. Theorists have now found that although this strategy requires extra processing time, the associated delays are less than expected because control signals can be scheduled when other qubits are busy.

Let Natural Selection Sharpen Your Writing Physicists often regard writing with dread, yet they can grow into stronger writers by embracing bad first drafts and trusting the evolutionary power of self-editing.

Scientists will find writing becomes easier if they stop striving for instant perfection and instead focus on incrementally improving a rough first draft, argues physicist and science writer Mark Buchanan.

In Active Solids, Connectivity Is as Important as Activity A robotic metamaterial shows that the odd mechanics of active solids depend on how the active constituents connect across the system.

Active materials could be used to make devices that spontaneously crawl over a difficult terrain—provided system-spanning networks are formed among the individual constituents of the system. Without the networks, microscopic activity remains local and the macroscopic response disappears.

In 1861 James Clerk Maxwell proposed that a magnet behaves like a spinning gyroscope. Now a research team has detected signatures of gyroscopic motion corresponding to Maxwell’s original ideas.

The conventional process for synthesizing ammonia is energy intensive and environmentally harmful. A greener alternative is now closer, thanks to theorists. They identified a semimetal whose topological surface states make it a potent catalyst for the process. physics.aps.org/articles/v19...

Measuring an Electron’s Magnetism in a Molecule Precise spectroscopy of a simple molecular ion opens a new path toward stringent tests of quantum electrodynamics.

The electron’s g factor characterizes its magnetic moment. Researchers have now determined g for the electron in an ionized molecule of hydrogen and deuterium with record precision. The feat could lead to finding physics beyond the standard model.

Hints of a Nucleus Irked by a Meson Houseguest Experiments with a proton beam striking a carbon target have uncovered events that may be due to a short-lived meson residing within a nucleus.

Researchers have found the first experimental indication of a nucleus temporarily hosting a heavy two-quark particle called the 𝜂′ meson. Though awaiting confirmation, this exotic nucleus could give new insights into quantum chromodynamics.

Oobleck Impacts Meet and Defy Expectations Dense drops of cornstarch and water usually stiffen when they strike a surface, but sometimes they flow fleetingly like a liquid.

Researchers used high-speed video and force measurements to capture how drops of cornstarch suspension, often referred to as Oobleck, act when they slam into a surface. The findings could help engineers better control complex fluids in 3D printing, industrial coating, and other applications.

Watching Atoms Make Waves A new microscope captures how atoms rearrange themselves when they are illuminated inside an optical cavity.

When atoms are placed inside a cavity, the photons they exchange cause the ensemble to rearrange itself into a periodic pattern called a density wave. Now researchers have built a microscope to image this light-induced density wave for the first time.

A Transparent Waveguide for Sound Acoustic waves can be guided through a narrow “tunnel” that lacks walls and thus presents no obstruction to sound traveling across its path.

Researchers have devised a “ghost tunnel”—a nearly perfect waveguide for sound that lets other sound waves cross its path undisturbed. The structure could find uses in complex sonar devices, where multiple signal channels must cross without interacting.

Nanoscale Imaging of Quantum Hall Currents Electrons in graphene follow various spiraling paths when they flow around a circular barrier under the influence of a magnetic field.

Researchers have adapted a 40-year-old technique, scanning tunneling potentiometry, to image current flows in a square sheet of graphene in an out-of-plane magnetic field. They found three distinct flow regimes, one of which surprised them.

What Network Structures Reveal About the Birds and the Bees Representing bird flocks and insect swarms as nodes connected in a complex structure yields new insights into animal collective behavior.

Researchers have modeled groups of different species of social birds and insects as graph networks. Among their findings: Honeybees interact with up to 10 neighbors in their collective but, depending on the task, sometimes much fewer.

Extending the Adiabatic Theorem Like its slowly perturbed counterpart, a rapidly perturbed quantum system stays closer to the ground state than to any excited state.

The quantum adiabatic theorem says that a slowly perturbed system stays in its instantaneous ground state. Now researchers have shown that this principle holds for the opposite limit: The ground state remains the most likely state even for a system subjected to an instantaneous perturbation.

Polyatomic Molecules Get Two Steps Closer to Quantum Horizon Researchers have improved trapping of polyatomic molecules while also controlling their collisions—two important advances for ultracold polyatomic molecular physics.

Researchers have trapped polyatomic molecules at high densities and ultralow temperatures. These feats pave the way to creating gases of polyatomic molecules, which could one day underlie quantum simulators, quantum computers, atomic clocks, and quantum sensors.

How Hair Cells in the Ear Actively Respond to Sound Our ability to hear relies on tiny “hair bundles” in the inner ear. A new thermodynamical model offers an explanation for the different ways that bundles oscillate.

Hair bundles are sensory organelles that convert mechanical input from sound into electrical output, which is then passed on to the brain. A new thermodynamic model suggests that hair bundles work like tiny machines that either extract power from incoming sound waves or inject power into them.

Distinguishing Neutron-Star Mergers from Black Hole Mergers Weak tidal forces alter the gravitational-wave signal from merging neutron stars by just enough that the telltale signature could be detected in large sensitive surveys.

Researchers have devised a new method that crunches through catalogs of gravitational-wave signals to infer an important number in stellar evolution: the fraction of mergers than involve neutron stars.

Symmetry Keeps Fermions Pure in a Noisy World A theoretical study reveals how to control and drive a quantum system without causing its decoherence.

Theorists have figured out a way to exploit certain symmetries to protect the quantum coherence of fermions in the face of invasive thermal noise and other perturbations.

Elucidating the Cosmic-Ray Knee New observations of cosmic rays that distinguish between hydrogen and helium find unexpected complexity in a long-observed spectral feature.

As the energy of cosmic rays rises, their flux drops, declining more steeply beyond a few peta-electron-volts. The origin of this spectral feature, known as the knee, remains a mystery. But now researchers at LHAASO in China have uncovered a new and potentially decisive clue.

Neutrinos Make a Break in the Ice The IceCube observatory at the South Pole has found evidence for a break in the spectrum of cosmic neutrinos, with theoretical implications for their generation.

After 14 years of harvesting cosmic neutrinos, IceCube now has evidence for a knee-like downward bend in the neutrino spectrum at an energy of around 30 TeV. The feature could mean that high-energy neutrinos originate from more than one type of source.

Parallel Production of Quantum Memories A new approach manufactures many high-quality diamond-based quantum memory chips simultaneously on a single wafer.

Researchers have demonstrated a way to create multiple diamond-based quantum memory chips in parallel on a single silicon wafer. The feat could enable quantum technologies to enjoy the same benefits of scaling as silicon-based classical technologies.

Corralling Interfering Anyons A delicate interference experiment elucidates the collective behavior of quasiparticles that are neither bosons nor fermions, but something in between.

Anyons—particles whose quantum statistics are between bosons and fermions—account for the hierarchy of fractional quantum Hall states. A new anyon experiment has shed light on the charge dynamics and thermodynamics of mesoscopic FQH physics.

A Lab Version of Planetary Atmospheres Researchers recreate key features of atmospheric turbulence in a meter-sized rotating cylinder.

A new analog model of a planetary atmosphere consists of a fluid in a rotating, meter-wide cylinder. Using video tracking, researchers charted how rotational motion is transferred from large vortices into smaller ones, a key feature of turbulence in real atmospheres.

Weighing Our Solar Neighborhood Measuring the acceleration of stellar remnants called pulsars helps researchers map how mass is distributed in our region of the Galaxy.

Researchers have used measurements of rapidly rotating neutron stars to infer the distribution of dark matter in the Galaxy. Although the results are tentative, they suggest that dark matter may not be distributed evenly above and below the Galactic disk.

A Time Crystal as a Clock New theoretical work shows how an unusual state of matter that oscillates between spin states could be used in timekeeping.

Researchers are investigating the timekeeping potential of continuous time crystals. These are systems that oscillate between different configurations despite being driven by a thermal gradient, a beam of light, or other aperiodic energy flow.

Can Before and After Be Superposed? Through a quantum-switch experiment, researchers attempt to reveal “indefinite causal order”—a quantum phenomenon involving events in a before-and-after superposition.

Quantum mechanics does not rule out superposition among a sequence of events. New experiments have not confined this so-called indefinite causal order, but they have closed several loopholes. The bizarre phenomenon could be real.

Refining Control of Quantum Memories A new technique efficiently and reliably manipulates information held in a quantum memory.

Researchers have demonstrated a way to efficiently control quantum information stored in a superconducting microwave while minimizing the errors that arise when the information is manipulated. The findings could help bring scalable, high-performance quantum computers closer to reality.

Spin Supercurrents in Superconducting Altermagnets Materials from a new class of magnets could host permanent dissipationless spin currents when they enter a superconducting state.

Theorists have predicted that a class of materials known as superconducting altermagnets can naturally generate and carry net spin supercurrents. Remarkably, these currents can propagate even in the presence of spin-orbit coupling and magnetic disorder.