Engineered defects in the diamond lattice hold promise for the storage and manipulation of quantum information. Entanglement between the electron and nuclear spins of two such defects is demonstrated at room temperature. Entanglement is the central yet fleeting phenomenon of quantum physics. Once being considered a peculiar counter-intuitive property of quantum theory1, it has developed into the most central element of quantum technology. Consequently, there have been a number of experimental demonstrations of entanglement between photons2, atoms3, ions4 and solid-state systems such as spins or quantum dots5,6,7, superconducting circuits8,9 and macroscopic diamond10. Here we experimentally demonstrate entanglement between two engineered single solid-state spin quantum bits (qubits) at ambient conditions. Photon emission of defect pairs reveals ground-state spin correlation. Entanglement (fidelity = 0.67±0.04) is proved by quantum state tomography. Moreover, the lifetime of electron spin entanglement is extended to milliseconds by entanglement swapping to nuclear spins. The experiments mark an important step towards a scalable room-temperature quantum device being of potential use in quantum information processing as well as metrology.

Rayleigh instability of copper nanowires has been experimentally demonstrated. After annealing $30–50\text{-}\mathrm{nm}$ -diam wires at temperatures between 400 and $600°\mathrm{C}$ , different stages of the fragmentation process are observed by scanning electron microscopy. At $400°\mathrm{C}$ , the wires start to fragment, forming shorter sections at $500°\mathrm{C}$ , and finally decaying into a chain of nanospheres at $600°\mathrm{C}$ . Average diameter and spacing of the spheres are in agreement with theoretical predictions. The Rayleigh instability applied to nanowires provides a structuring technique producing long chains of nanospheres, which should find interesting applications, for instance, by guiding light below the diffraction limit via coherent coupling of surface-plasmon polaritons.

The great potential of nanoporous membranes for water filtration and chemical separation has been challenged by the trade-off between selectivity and permeability. Here we report on nanoporous polymer membranes with an excellent balance between selectivity and permeability of ions. Our membranes are fabricated by irradiating 2-μm-thick polyethylene terephthalate Lumirror® films with GeV heavy ions followed by ultraviolet exposure. These membranes show a high transport rate of K⁺ ions of up to 14 mol h⁻¹ m⁻² and a selectivity of alkali metal ions over heavy metal ions of >500. Combining transport experiments and molecular dynamics simulations with a polymeric nanopore model, we demonstrate that the high permeability is attributable to the presence of nanopores with a radius of ~0.5 nm and a density of up to 5 × 10¹⁰ cm⁻², and the selectivity is ascribed to the interaction between the partially dehydrated ions and the negatively charged nanopore wall.

We report on the observation of a fine structure in ion tracks in amorphous ${\mathrm{SiO}}_2$ using small angle x-ray scattering measurements. Tracks were generated by high energy ion irradiation with Au and Xe between 27 MeV and 1.43 GeV. In agreement with molecular dynamics simulations, the tracks consist of a core characterized by a significant density deficit compared to unirradiated material, surrounded by a high density shell. The structure is consistent with a frozen-in pressure wave originating from the center of the ion track as a result of a thermal spike.

Using profilometry, large out-of-plane swelling was found when irradiating lithium fluoride with MeV to GeV heavy ions. The effect scales with the range of ions and is linked to the electronic energy loss. Above a critical energy loss of 4.2 keV/nm, ion-induced swelling increases by two to three orders of magnitude. The threshold is much lower than 10 keV/nm required for track etching, suggesting swelling measurements as a suitable technique for testing in particular nonamorphisable material sensitivity versus swift heavy-ion irradiation. A quantitative comparison with data available from x-ray and neutron irradiations indicates that swelling in LiF results from an intermediate defect zone in between the track halo (10–20 nm) consisting mainly of single color centers and the track core (1–2 nm) identified by small-angle x-ray scattering.