Physics, astronomy and space science.
A theoretical study proposes an experiment in which a mass placed in a quantum superposition could produce an effectively repulsive gravitational effect on another particle. The effect would arise from quantum interference and, if observed, would conflict with general relativity’s description of gravity as always attractive.
Researchers report that silicon spin qubits can perform precise operations in parallel, overcoming a major source of error during simultaneous control. In a five-qubit array, gate fidelities stayed above 99.99% for up to three qubits and above 99.9% when all five operated together.
A survey of MESSENGER measurements identified 116 candidate magnetic reconnection layers near Mercury’s magnetopause. The structures appear to recur under the planet’s typically low-Alfvén-Mach-number solar wind, but they cannot yet be confirmed as reconnection outflows.
Researchers developed an AI system that rapidly estimates where a tsunami began and the earthquake fault conditions that produced it. Tests with simulated data and real observations from Japan’s 2024 Hyuga-nada earthquake produced source estimates within a few minutes.
Simulations involving thousands of language-model agents found that their opinions could become polarized as they interacted over time. The agents also formed clustered social networks, allowing researchers to test how diverse interactions and confirmation bias might affect division.
Researchers have realized an optical clock based on a nuclear transition in thorium-229, using a laser stabilized to radiation absorbed by thorium nuclei in a calcium fluoride crystal. The clock was also used to search for periodic changes and slow drifts that could indicate interactions between ultralight dark matter and fundamental forces.
Astronomers report a possible second-generation planet orbiting the white dwarf HS 0209+0832. Its unusual chemical signature and a repeating 4.399-day brightness signal are consistent with an evaporating gas giant formed from material expelled by the star.
Researchers generated quantum entanglement between a levitated silica nanosphere and a propagating optical field at room temperature. The result suggests that levitated mechanical systems could connect stationary objects with light for quantum communication and tests of macroscopic quantum physics.
A study in The Astrophysical Journal examines how black holes in isolated pairs could acquire spins that are tilted relative to their orbit or point in the opposite direction. The results suggest these features are not necessarily evidence that a pair formed through close encounters in a dense stellar environment.
Laboratory experiments show that palladium minerals associated with serpentinizing hydrothermal vents can turn phosphite into phosphate and attach phosphate to molecules involved in biology. The reactions produced several phosphate-based energy compounds without sulfur, suggesting a possible geochemical route toward early metabolism.
Researchers found that modest in-plane mechanical stress greatly increased superconductivity in lanthanum-barium copper oxide at the 1/8 doping level, where stripe order normally suppresses bulk superconductivity. The material reached zero resistance at 37 kelvin, while the transition began at up to 46 kelvin.
Researchers have grown epitaxial potassium-niobium oxide films on silicon, addressing a longstanding challenge caused by potassium loss during production. The films showed an electro-optic response at a wavelength used in communications, while simulations suggest strain could increase that response.
A joint analysis of the neutron-star merger GW170817 and the gamma-ray burst GRB 170817A found no evidence that the gravitational constant has changed over time. The study limits its fractional rate of change to between −3.36 × 10⁻⁹ and 5.34 × 10⁻¹⁰ per year.
Researchers developed a neural-network design that enforces exact Lorentz symmetry with minimal additional computational overhead. They applied it to graph-based networks and transformers for particle-physics tasks including amplitude prediction, event generation and identifying jets from top quarks.
Two room-temperature lutetium-ion clocks achieved fractional frequency uncertainties near one part in 10¹⁹ and agreed in a direct comparison. The result supports efforts to improve international timekeeping and develop a future definition of the second.
