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Single nuclear spin detection and control in a van der Waals material
United States · Single nuclear spin detection and control in a van der Waals material - United StatesOptically active spin defects in solids1,2 are leading candidates for quantum sensing3,4 and quantum networking5,6. Recently, single spin defects were discovered in hexagonal boron nitride (hBN)7–11, a layered van der Waals (vdW) material. Owing to its two-dimensional structure, hBN allows spin defects to be positioned closer to target samples than in three-dimensional crystals, making it ideal for atomic-scale quantum sensing12, including nuclear magnetic resonance (NMR) of single molecules. However, the chemical structures of these defects7–11 remain unknown and detecting a single nuclear spin with a hBN spin defect has been elusive. Here we report the creation of single spin defects in hBN using 13C ion implantation and the identification of three distinct defect types based on hyperfine interactions. We observed both S = 1/2 and S = 1 spin states within a single hBN spin defect. We demonstrated atomic-scale NMR and coherent control of individual nuclear spins in a vdW material, with a π-gate fidelity up to 99.75% at room temperature. By comparing experimental results with density functional theory (DFT) calculations, we propose chemical structures for these spin defects. Our work advances the understanding of single spin defects in hBN and provides a pathway to enhance quantum sensing using hBN spin defects with nuclear spins as quantum memories. The detection and coherent control of single 13C nuclear spins in hexagonal boron nitride at room temperature enables the use of van der Waals materials in upcoming quantum technologies.

New "theory of everything" could finally make 'quantum gravity' a reality — and prove #Einstein wrong
The proposed theory grapples with the fact that #quantummechanics (basically modern #physics) and #generalrelativity (#Einstein's theory of gravity) both describe the universe perfectly, but are mathematically incompatible with each other.
livescience.com/physics-mathem

Live Science · New theory could finally make 'quantum gravity' a reality — and prove Einstein wrongBy Andrey Feldman

Bow Shock Instability

There are few flows more violent than planetary re-entry. Crossing a shock wave is always violent; it forces a sudden jump in density, temperature, and pressure. But at re-entry speeds this shock wave is so strong the density can jump by a factor of 13 or more, and the temperature increase is high enough that it literally rips air molecules apart into plasma.

Here, researchers show a numerical simulation of flow around a space capsule moving at Mach 28. The transition through the capsule’s bow shock is so violent that within a few milliseconds, all of the flow behind the shock wave is turbulent. Because turbulence is so good at mixing, this carries hot plasma closer to the capsule’s surface, causing the high temperatures visible in reds and yellows in the image. Also shown — in shades of gray — is the vorticity magnitude of flow around the capsule. (Image credit: A. Álvarez and A. Lozano-Duran)