Renato Fabiano Matheus - Ciência e tecnologia

Ciência e tecnologia
Nature Physics - Issue - nature.com science feeds
Nature Physics offers a unique mix of news and reviews alongside top-quality research papers. Published monthly, in print and online, the journal reflects the entire spectrum of physics, pure and applied.

Five minutes from disaster Nuclear weapons, nuclear power and climate change are driving the march of the Doomsday Clock towards midnight. Out of the darkness The web blackout symbolized concern over potential legislation, which we share. Can't get no diffraction? Just like that Behind the screen Upholding the law Millikan recharged Quantum chemistry cut short Quantum speed limit How the galaxy got its field Entanglement preservation: The Sleeping Beauty approach Two-qubit entanglement can be preserved by partially measuring the qubits to leave them in a 'lethargic' state. The original state is restored using quantum measurement reversal after the qubits have travelled through a decoherence channel. Thermodynamics: A Stirling effort The realization of a single-particle Stirling engine pushes thermodynamics into stochastic territory where fluctuations dominate, and points towards a better understanding of energy transduction at the microscale. Optomechanical systems: Hot electrons but cool vibrations The electronic degrees of freedom in semiconductor membranes provide an innovative new way of cooling mechanical motion. Graphene: Carbon's superconducting footprint Graphene exhibits many extraordinary properties, but superconductivity isn't one of them. Two theoretical studies suggest that by decorating the surface of graphene with the right species of dopant atoms, or by using ionic liquid gating, superconductivity could yet be induced. Quasicrystals: Unearthly beauty Quantum control: Through the quantum chicane In quantum control there is an inherent tension between high fidelity requirements and the need for speed to avoid decoherence. A direct comparison of quantum control protocols at these two extremes indicates where the sweet spot may lie. Information storage: Dense bytes from antiferromagnetic bits Semiconductor spintronics: Doppler speed gun for spins An experimental technique based on Doppler velocimetry provides a detailed picture of electronic spins as they diffuse, drift and turn under the action of an electric field in a two-dimensional electron gas. Materials physics: Sleight of handedness Protecting entanglement from decoherence usingÂ weak measurement and quantum measurementÂ reversal The unavoidable coupling between a quantum state and its environment leads to decoherence. Weak measurementsâ€”indirectly observing a quantum state without disturbing itâ€”are now shown to be a useful tool for reducing or even nullifying the effects of decoherence. Magnetoelectric resonance with electromagnons in a perovskite helimagnet Electromagnons are excitations that exhibit both electric and magnetic dipole moments, and are expected to enhance the coupling of magnetization and polarization in multiferroic materials. The identification of electromagnons in a perovskite helimagent may be useful in the development of ways to manipulate light. Phase separation and magnetic order in K-doped iron selenide superconductor The discovery that potassium-doped iron selenide undergoes phase separation into a defect-free superconducting phase and an iron-vacancy-ordered insulating phase resolves many questions about the unusual behaviour of this iron-based superconductor. Phonon-mediated superconductivity in graphene by lithium deposition Graphene exhibits many extraordinary properties. But, despite many attempts to find ways to induce it, superconductivity is not one of them. First-principles calculations suggest that by decorating the surface of graphene with lithium atoms, it could yet be made to superconduct. Imaging molecular potentials using ultrahigh-resolution resonant photoemission Photoelectron spectroscopy is an invaluable tool for better understanding the energy levels of molecules. However, many levels remain hidden because of transition selection rules or a high density of states. Using X-rays to excite coreâ€“shell electrons and monitoring their Auger decay enables the extraction of previously hidden molecular-potential curves. Focusing of short-pulse high-intensity laser-accelerated proton beams When an intense laser pulse hits a flat metal foil, it ejects a spray of high-energy protons. Laser irradiation of a curved foil covering the tip of a hollow cone focuses the protons to intensities that could be useful for generating extreme states of matter. Realization of a micrometre-sized stochastic heatÂ engine An optically trapped colloidal particle serves as the first realization of a stochastic thermal engine, extending our understanding of the thermodynamics behind the Carnot cycle to microscopic scales where fluctuations dominate. High-fidelity quantum driving Transforming a quantum system with high fidelity is usually a trade-off between an increase in speedâ€”thereby minimizing decoherenceâ€”and robustness against fluctuating control parameters. Protocols at these two extreme limits are now demonstrated and compared using Boseâ€“Einstein condensates in optical traps. Doppler velocimetry of spin propagation in a two-dimensional electron gas An optical technique based on Doppler velocimetry reveals important aspects of the physics underlying the propagation of spin polarization in a two-dimensional electron gas. The spin mobility is shown to track the high electron mobility, but coherent spin precession is lost at temperatures near 150â€‰K, posing a challenge for future spintronics devices. Chiral superconductivity from repulsive interactions in doped graphene Chiral superconducting states are expected to support a variety of exotic and potentially useful phenomena. Theoretical analysis suggests that just such a state could emerge in a doped graphene monolayer. Non-monotonic temperature evolution of dynamic correlations in glass-forming liquids Glass-forming liquids are generally thought to relax through a collective rearrangement of domains, correlated over a length scale that increases with decreasing temperature. A numerical study now reveals a surprising twist to the story, claiming that relaxation depends non-monotonically on temperature.