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Category: particle physics – Page 14

The Anderson transition is a phase transition that occurs in disordered systems, which entails a shift from a diffusive state (i.e., in which waves or particles are spread out) to a localized state, in which they are trapped in specific regions. This state was first studied by physicist Philip W. Anderson, who examined the arrangement of electrons in disordered solids, yet it was later found to also apply to the propagation of light and other waves.

Researchers at Missouri University of Science & Technology, Yale University, and Grenoble Alpes University in France recently set out to further explore the Anderson transition for light (i.e., electromagnetic waves) in 3D disordered systems.

Their paper, published in Physical Review Letters, outlines the simulation of light wave transport in an arrangement of perfect-electric-conducting (PEC) spheres, materials that reflect electromagnetic waves.

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A research team from the University of Science and Technology of China has demonstrated the ability to electrically manipulate the spin filling sequence in a bilayer graphene (BLG) quantum dot (QD). This achievement, published in Physical Review Letters, showcases the potential to control the spin degree of freedom in BLG, a material with promising applications in quantum computing and advanced electronics.

BLG has drawn extensive attention in recent years due to its . When an out-of-plane electric field is applied, it can generate a tunable band gap. Moreover, the trigonal warping effect, caused by the skew interlayer coupling, gives rise to additional minivalley degeneracy, greatly influencing the behavior of charge carriers. Quantum dot devices, which can precisely control the number of charge carriers, have become a crucial tool for studying these phenomena at the single-particle level.

The research team delved into the intricate dynamics of electron shell structures within quantum dot, focusing on how these structures can be manipulated through the trigonal warping effect, a unique feature of bilayer graphene. They employed a highly tunable quantum dot device, which provided the means to control the electron filling sequence. They began by applying a small perpendicular electric field, observing that the s-shell filled with four electrons, two with spin-up and two with spin-down, each from opposite valleys.

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Three and a half kilometers beneath the Mediterranean Sea, around 80km off the coast of Sicily, lies half of a very unusual telescope called KM3NeT.

The enormous device is still under construction, but today the telescope’s scientific team announced they have already detected a particle from with a staggering amount of energy.

In fact, as the team report in Nature, they found the most energetic neutrino anyone has ever seen—and it represents a tremendous leap forward in exploring the uncharted waters of the extreme universe.

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Researchers have made a breakthrough in THz frequency conversion using graphene.

Graphene is an allotrope of carbon in the form of a single layer of atoms in a two-dimensional hexagonal lattice in which one atom forms each vertex. It is the basic structural element of other allotropes of carbon, including graphite, charcoal, carbon nanotubes, and fullerenes. In proportion to its thickness, it is about 100 times stronger than the strongest steel.

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Using laser trapped atom lattices instead of solid metamaterials to achieve negative refraction!

A Beam of Light Undergoing Negative Refraction Within a Lattice of Laser-Trapped Atoms

A Beam of Light Undergoing Negative Refraction Within a Lattice of Laser-Trapped Atoms.

Highlights:

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In the grand sweep of scientific history, revolutions in thought are often born from a simple yet unsettling realization: that the fundamental nature of reality is not what we once assumed it to be. In the 20th century, physics was shaken by the twin cataclysms of relativity and quantum mechanics, revealing that space and time themselves were malleable, that particles could exist in superpositions, and that observation played a fundamental role in shaping what we call reality.

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Light-sensitive nanoparticles promise a wide range of applications, for example in the field of sensor technology or energy generation. However, these require knowledge and control of the processes taking place within them. Plasmons, collective electron movements in the nanoparticle which transport energy, are essential in the behaviour of such nanoparticles.

Time-resolved experiments in the attosecond range reveal now that the importance of electronic correlations in these plasmons increases when the size of a system decreases to scales of less than one nanometre.

The study, published in the journal Science Advances (“Correlation-driven attosecond photoemission delay in the plasmonic excitation of C 60 fullerene”), was led by the University of Hamburg and DESY as part of a collaboration with Stanford, SLAC National Accelerator Laboratory, Ludwig-Maximilians-Universität München (LMU), Northwest Missouri State University, Politecnico di Milano and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD).

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A team of physicists at Fudan University, working with colleagues from Henan University, both in China, and from Nanyang Technological University, in Singapore and Donostia International Physics Center, in Spain, has developed a way to generate topological structures in surface water using gravity water waves. In their study published in Nature, the group used their technique to generate structures such as wave vortices, skyrmions and Möbius strips.

Prior research has shown that various types of waves can be used to achieve desired goals in a variety of applications; , for example, are used to capture and manipulate individual or groups of molecules to create materials or test molecular properties. Sound waves can be used to control much larger particles, or even objects, such as the membrane in a stereo speaker.

For this new study, the research team found a way to generate topological structures on the surface of water by taking advantage of the noise that develops when waves are laid on top of one another, giving them topological properties that can be used to generate wave fields.

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