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Category: particle physics – Page 180

Engineers make tunable, shape-changing metamaterial inspired by vintage toys

Common push puppet toys in the shapes of animals and popular figures can move or collapse with the push of a button at the bottom of the toys’ base. Now, a team of UCLA engineers has created a new class of tunable dynamic material that mimics the inner workings of push puppets, with applications for soft robotics, reconfigurable architectures and space engineering.

Inside a push puppet, there are connecting cords that—when pulled taut—will make the toy stand stiff. But by loosening these cords, the “limbs” of the toy will go limp. Using the same cord tension-based principle that controls a puppet, researchers have developed a new type of metamaterial, a material engineered to possess properties with promising advanced capabilities.

Published in Materials Horizons, the study demonstrates the new lightweight metamaterial, which is outfitted with either motor-driven or self-actuating cords that are threaded through interlocking cone-tipped beads. When activated, the cords are pulled tight, causing the nesting chain of bead particles to jam and straighten into a line, making the material turn stiff while maintaining its overall structure.

Quantum sensor detects magnetic and electric fields from a single atom

The next step, says Esat, is to increase the new device’s magnetic field sensitivity by implementing more advanced sensing protocols based on pulsed electron spin resonance schemes and by finding molecules with longer spin decoherence times. “We hope to increase the sensitivity by a factor of about 1,000, which would allow us to detect nuclear spins at the atomic scale,” he says.

A holy grail for quantum sensing

The new atomic-scale quantum magnetic field sensor should also make it possible to resolve spins in certain emerging two-dimensional quantum materials. These materials are predicted to have many complex magnetic orders, but they cannot be measured with existing instruments, Heinrich and his QNS colleague Yujeong Bae note. Another possibility would be to use the sensor to study so-called encapsulated spin systems such as endohedral-fullerenes, which comprise a magnetic core surrounded by an inert carbon cage.

World’s first micromachine twists 2D materials at will

Just a few years ago, researchers discovered that changing the angle between two layers of graphene, an atom-thick sheet of carbon, also changed the material’s electronic and optical properties. They then learned that a “twist” of 1.1 degrees—dubbed the “magic” angle—could transform this metallic material into an insulator or a superconductor, a finding that ignited excitement about a possible pathway to new quantum technologies.

Deviations in particle interactions point to the existence of new bosons

The Standard Model of particle physics is the mathematical description of the fundamental constituents and interactions of matter. While it is the accepted theory encapsulating our current state-of-the-art knowledge in particle physics, it is incomplete as it is unable to describe many glaring phenomena in nature.

Crivellin and Mellado’s article describes deviations in the decay of multi-lepton particles in the LHC, compared to how they should behave according to the Standard Model. These deviations, or anomalies, constitute excesses in the production of particles called electrons and its heavy cousin, the muon, on top of the predictions from the Standard Model.

“An is something that stands out as unusual or different from what is normal or expected. In this case, this is a deviation from the Standard Model of Particle physics. Anomalies can be important because they often signal that something unexpected or significant has happened,” says Crivellin.

Multiverse as an Ensemble of Stable and Unstable Universes

Read the paper published in our journal Symmetry:, which has been viewed many times, authored by Krzysztof Urbanowski (Uniwersytet Zielonogórski)

Estimates of the Higgs and top quark masses, mH≃125.10±0.14 [GeV] and mt≃172.76±0.30[GeV], based on the experimental result place the Standard Model in the region of the metastable vacuum. A consequence of the metastability of the Higgs vacuum is that it should induce the decay of the electroweak vacuum in the early Universe with catastrophic consequences. It may happen that certain universes were lucky enough to survive the time of canonical decay, that is the exponential decay, and live longer. This means that it is reasonable to analyze conditions allowing for that. We analyze the properties of an ensemble of universes with unstable vacua considered as an ensemble of unstable systems from the point of view of the quantum theory of unstable states. We found some symmetry relations for quantities characterizing the metastable state.

Molecular wires with a twist

From the high-voltage wires that carry electricity over long distances, to the tungsten filaments in our incandescent lights, we may have become accustomed to thinking that electrical conductors are always made of metal. But for decades, scientists have been working on advanced materials based on carbon-based oligomer chains that can also conduct electricity. These include the organic light-emitting devices found in some modern smartphones and computers.

In quantum mechanics, electrons are not just point particles with definite positions, but rather can become ‘delocalized’ over a region. A molecule with a long stretch of alternating single-and double-bonds is said to have pi-conjugation, and conductive polymers operate by allowing delocalized electrons to hop between pi-conjugated regions – somewhat like a frog hopping between nearby puddles. However, the efficiency of this process is limited by differences in the energy levels of adjacent regions.

Fabricating oligomers and polymers with more uniform energy levels can lead to higher electrical conductivity, which is necessary for the development of new practical organic electronics, or even single-molecule wires.

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