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Category: particle physics – Page 57

Photons, electrons, and other particles can propagate as wave packets with helical wave fronts that carry an orbital angular momentum. These vortex states can be used to probe the dynamics of atomic, nuclear, and hadronic systems. Recently, researchers demonstrated vortex states of x-ray photons and proposed ways to realize such states for particles at higher energies (MeV to GeV). But verifying high-energy vortex states will be challenging, because characterization techniques used at lower energies would perform poorly. Zhengjiang Li of Sun Yat-sen University in China and his colleagues at Shanghai Institute of Optics and Fine Mechanics propose a new diagnostic method for high-energy vortex states. Their approach would reveal such states through an exotic scattering phenomenon called a superkick.

A superkick is a theorized effect occurring when an atom placed near the axis of a vortex light beam absorbs a photon. Under such conditions, the atom may get kicked to the side with a transverse momentum greater than that carried by the photon. Li and his colleagues considered a similar superkick involving electrons. They analyzed the elastic head-on collision of two electron wave packets at 10 MeV, one in a vortex state and the other in a nonvortex one. According to their calculations, two electrons in the beam, upon scattering, would acquire a nonzero total transverse momentum that could be detectable. The researchers predict an unmistakable signature of the vortex state: The momentum imbalance increases as the collision point gets closer to the vortex axis.

The researchers expect the superkick effect—which has never been observed—to be detectable with realistic experimental settings. They say the idea could be extended to high-energy vortices of photons, ions, and even hadrons.

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The Large Hadron Collider (LHC), the world’s largest and most powerful particle accelerator, is also the largest single machine operating in the world today that uses superconductivity. The proton beams inside the LHC are bent and focused around the accelerator ring using superconducting electromagnets. These electromagnets are built from coils, made of niobium–titanium (Nb–Ti) cables, that have to operate at a temperature colder than that of outer space in order to be superconducting. This allows the current to flow without any resistance or loss of energy. The High-Luminosity LHC (HL-LHC), an upgrade of the LHC, will for the first time feature innovative electrical transfer lines known as the “Superconducting Links”

Recently, CERN’s SM18 magnet test facility witnessed the successful integration of the first series of magnesium diboride superconducting cables into a novel, flexible cryostat. Together with high-temperature superconducting (HTS) magnesium diboride (MgB2) cables, they will form a unique superconducting transfer line to power the HL-LHC inner triplet magnets. The triplets are the focusing magnets that focus the beam, right before collisions, to a diameter as narrow as 5 micrometres.

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Sometimes things are a little out of whack, and it turns out to be exactly what you need.

That was the case when orthoferrite crystals turned up at a Rice University laboratory slightly misaligned. Those crystals inadvertently became the basis of a discovery that should resonate with researchers studying spintronics-based quantum technology.

Rice physicist Junichiro Kono, alumnus Takuma Makihara and their collaborators found an orthoferrite material, in this case yttrium iron oxide, placed in a high magnetic field showed uniquely tunable, ultrastrong interactions between magnons in the crystal.

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Engineers at Northwestern University have demonstrated quantum teleportation over a fiber optic cable already carrying Internet traffic. This feat, published in the journal Optica, opens up new possibilities for combining quantum communication with existing Internet infrastructure. It also has major implications for the field of advanced sensing technologies and quantum computing applications.

Quantum teleportation, a process that harnesses the power of quantum entanglement, enables an ultra-fast and secure method of information sharing between distant network users. Unlike traditional communication methods, quantum teleportation does not require the physical transmission of particles. Instead, it relies on entangled particles exchanging information over great distances.

Nobody thought it would be possible to achieve this, according to Professor Prem Kumar, who led the study. “Our work shows a path towards next-generation quantum and classical networks sharing a unified fiber optic infrastructure. Basically, it opens the door to pushing quantum communications to the next level.”

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String theory proposes that all particles and forces are made of tiny, vibrating strings, which form the fundamental building blocks of the universe. This framework offers a potential solution to the long-standing paradoxes surrounding black holes, such as their singularities—infinitely tiny points where the laws of physics break down—and the Hawking radiation paradox, which questions the fate of information falling into black holes.

Fuzzballs replace the singularity with an ultra-compressed sphere of strings, likened to a neutron star’s structure but composed of subatomic strings instead of particles. While the theory remains incomplete, its implications are significant, offering an alternative explanation for phenomena previously attributed to black holes.

To differentiate between black holes and fuzzballs, researchers are turning to gravitational waves—ripples in spacetime caused by cosmic collisions. When black holes merge, they emit specific gravitational wave signatures that have so far aligned perfectly with Einstein’s general relativity. However, fuzzballs might produce subtle deviations from these patterns, providing a way to confirm their existence.

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Scientists from the ALICE (A Large Ion Collider Experiment) at CERN’s Large Hadron Collider reported evidence of a new antimatter particle called antihyperhelium-4, essentially the “evil twin” of another weird particle called hyperhelium-4. This incredibly exotic form of matter contains two antiprotons, an antineutron, and an unstable particle called an antilambda comprised of subatomic quarks.

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Entanglement is perhaps one of the most confusing aspects of quantum mechanics. On its surface, entanglement allows particles to communicate over vast distances instantly, apparently violating the speed of light. But while entangled particles are connected, they don’t necessarily share information between them.

In quantum mechanics, a particle isn’t really a particle. Instead of being a hard, solid, precise point, a particle is really a cloud of fuzzy probabilities, with those probabilities describing where we might find the particle when we go to actually look for it. But until we actually perform a measurement, we can’t exactly know everything we’d like to know about the particle.

These fuzzy probabilities are known as quantum states. In certain circumstances, we can connect two particles in a quantum way, so that a single mathematical equation describes both sets of probabilities simultaneously. When this happens, we say that the particles are entangled.

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Which brings us to the big question: what about gravity?

This is something where we can’t be certain, as gravitation remains the only known force for which we don’t have a full quantum description. Instead, we have Einstein’s general relativity as our theory of gravity, which relies on a purely classical (i.e., non-quantum) formalism for describing it. According to Einstein, spacetime behaves as a four-dimensional fabric, and it’s the curvature and evolution of that fabric that determines how matter-and-energy move through it. Similarly it’s the presence and distribution of matter-and-energy that determine the curvature and evolution of spacetime itself: the two notions are linked together in an inextricable way.

Now, over on the quantum side, our other fundamental forces and interactions have both a quantum description for particles and a quantum description for the fields themselves. All calculations performed within all quantum field theories are calculated within spacetime, and while most of the calculations we perform are undertaken with the assumption that the underlying background of spacetime is flat and uncurved, we can also insert more complex spacetime backgrounds where necessary. It was such a calculation, for example, that led Stephen Hawking to predict the emission of the radiation that bears his name from black holes: Hawking radiation. Combining quantum field theory (in that case, for electromagnetism) with the background of curved spacetime inevitably leads to such a prediction.

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