In this work, we show that the flexible programming of the exchange-biased magnetic heterostructure enables the direct generation of various structured terahertz beams with complex polarization distributions. In the above demonstrations, we did not perform amplitude design on E_NF(r), as lasers with Gaussian profiles were utilized to excite various programmed emitters. To exert control over local NF amplitudes, spatial light modulators can be further employed to manipulate the amplitude profiles of excitation lasers.

It is important to acknowledge that, owing to the inherent capability of generating only linearly polarized E_NF locally, a crucial constraint arises: the NF terahertz amplitudes for the LCP and RCP components must be equal at all locations, leading to \({A}_{NF}^{L}(\mathbf{r})={A}_{NF}^{R}(\mathbf{r})\) at the emitter’s surface. As a consequence, both LCP and RCP terahertz fields are simultaneously generated in the far field. In situations where terahertz beams with a pure polarization state are of interest, one can strategically design the magnetization pattern so that desired polarization state is focused at the center, while surrounding it with other polarizations. By employing simple spatial filtering, this pure polarization state can be isolated and utilized. This concept was demonstrated by the LCP Gaussian beam in the last demonstration, where different spatial phase gradients were applied on the LCP and RCP light beams, allowing for their spatial separation in the far field.

Furthermore, by fabricating the heterostructures into appropriately oriented micro-structures, one can induce confinements onto the local charge currents [38,39,40]. This enables independent control over the x- and y-components of the local terahertz fields, potentially facilitating the realization of an arbitrary terahertz wave generator.

In 1968, deep underground in the Homestake gold mine in South Dakota, Ray Davis Jr.

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At the same time, Steven Weinberg and Abdus Salam were carrying out major construction work on what would become the Standard Model of particle physics, building the Higgs mechanism into Sheldon Glashow’s unification of the electromagnetic and weak interactions. The Standard Model is still bulletproof today, with one proven exception: the nonzero neutrino masses for which Davis’s observations were in hindsight the first experimental evidence.

Today, neutrinos are still one of the most promising windows into physics beyond the Standard Model, with the potential to impact many open questions in fundamental science ( CERN Courier May/June 2024 p29). One of the most ambitious experiments to study them is currently taking shape in the same gold mine as Davis’s experiment more than half a century before.

In February this year, the international Deep Underground Neutrino Experiment (DUNE) completed the excavation of three enormous caverns 1.5 kilometres below the surface at the new Sanford Underground Research Facility (SURF) in the Homestake mine. 800,000 tonnes of rock have been excavated over two years to reveal an underground campus the size of eight soccer fields, ready to house four 17,500 tonne liquid–argon time-projection chambers (LArTPCs). As part of a diverse scientific programme, the new experiment will tightly constrain the working model of three massive neutrinos, and possibly even disprove it.

Scientists spent ages mocking panpsychism. Now, some are warming to the idea that plants, cells, and even atoms are conscious.

Every few thousand years, the Sun unleashes a burst of high-energy particles that can have serious consequences for life on Earth.

The machine works by manipulating particles in a water bath to generate usable power.