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Category: particle physics – Page 437

Study observes the coexistence of topological edge states and superconductivity in stanene films

Stanene is a topological insulator comprised of atoms typically arranged in a similar pattern to those inside graphene. Stanene films have been found to be promising for the realization of numerous intriguing physics phases, including the quantum spin Hall phase and intrinsic superconductivity.

Some also suggested that these films could host topological , a state that is particularly valuable for the development of quantum computing technology. So far, however, topological edge states in stanene had not been reliably and consistently observed in experimental settings.

Researchers at Shanghai Jiao Tong University, the University of Science and Technology of China, Henan University, Zhengzhou University, and other institutes in China have recently demonstrated the coexistence of topological edge states and superconductivity in one to five-layer stanene films placed on the Bi(111) . Their observations, outlined in a paper published in Physical Review Letters, could have important implications for the development of Stanene-based quantum devices.

Liquid metal boosts platinum catalyst’s activity 1000 times

Adam FordAdmin.

I disagree with Ross Dawson here… it’s not ultimately a matter of belief or faith, it’s a matter of understanding our existing knowledge about the physiology of sentience, and of furthering the relevant research agendas. Questions of sentience in h… See more.

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Quantum electrodynamics tested 100 times more accurately than ever

Using a newly developed technique, scientists at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg have measured the very small difference in the magnetic properties of two isotopes of highly charged neon in an ion trap with previously inaccessible accuracy. Comparison with equally extremely precise theoretical calculations of this difference allows a record-level test of quantum electrodynamics (QED). The agreement of the results is an impressive confirmation of the standard model of physics, allowing conclusions regarding the properties of nuclei and setting limits for new physics and dark matter.

Electrons are some of the most fundamental building blocks of the matter we know. They are characterized by some very distinctive properties, such as their negative charge and the existence of a very specific intrinsic angular momentum, also called spin. As a charged particle with spin, each electron has a magnetic moment that aligns itself in a magnetic field similar to a compass needle. The strength of this magnetic moment, given by the so-called g-factor, can be predicted with extraordinary accuracy by quantum electrodynamics. This calculation agrees with the experimentally measured g-factor to within 12 digits, one of the most precise matches of theory and experiment in physics to date. However, the magnetic moment of the electron changes as soon as it is no longer a “free” particle, i.e., unaffected by other influences, but instead is bound to an atomic nucleus, for example.

Physicists build an atom laser that can stay on forever

Lasers produce coherent waves of light: All the light inside a laser vibrates completely in sync. Meanwhile, quantum mechanics tells us that particles like atoms should also be thought of as waves. As a result, we can build “atom lasers” containing coherent waves of matter. But can we make these matter waves last, so that they may be used in applications? In research that was published in Nature this week, a team of Amsterdam physicists shows that the answer to this question is affirmative.

Getting bosons to march in sync

The concept that underlies the atom laser is the so-called Bose-Einstein Condensate, or BEC for short. Elementary particles in nature occur in two types: fermions and bosons. Fermions are particles like electrons and quarks—the building blocks of the matter that we are made of. Bosons are very different in nature: they are not hard like fermions, but soft: for example, they can move through one another without a problem. The best-known example of a boson is the photon, the smallest possible quantity of light. But matter particles can also combine to form bosons—in fact, entire can behave just like particles of light. What makes bosons so special is that they can all be in the exact same state at the exact same time, or phrased in more technical terms, they can “condense” into a coherent wave. When this type of condensation happens for matter particles, physicists call the resulting substance a Bose-Einstein Condensate.

Grand Unification as a Bridge Between String Theory And Phenomenology

Circa 2006 string theory would explain everything even extradimensional beings or even weird phenomenon. Basically it could even explain something even greater about our existence that even a God level entity had a grand design of our universe. It could even explain miracles by these entities using string theory. Even Einstein thought that there could be a great designer and oddly enough this could explain all things in physics and our world even an infinite multiverse that our universe is much more odd then we previously thought. String theory could even essentially be the next step after quantum mechanics.

In the first part of this paper, we explain what empirical evidence points to the need for having an effective grand unification-like symmetry possessing the symmetry SU-color in 4D. If one assumes the premises of a future predictive theory including gravity — be it string/M-theory or a reincarnation — this evidence then suggests that such a theory should lead to an effective grand unification-like symmetry as above in 4D, near the string-GUT-scale, rather than the standard model symmetry. Advantages of an effective supersymmetric G(224) = SU L × SU R × SU c or SO(10) symmetry in 4D in explaining (i) observed neutrino oscillations, (ii) baryogenesis via leptogenesis, and (iii) certain fermion mass-relations are noted. And certain distinguishing tests of a SUSY G(224) or SO(10)-framework involving CP and flavor violations (as in μ → eγ, τ → μγ, edm’s of the neutron and the electron) as well as proton decay are briefly mentioned.

Recalling some of the successes we have had in our understanding of nature so far, and the current difficulties of string/M-theory as regards the large multiplicity of string vacua, some comments are made on the traditional goal of understanding vis a vis the recently evolved view of landscape and anthropism.

Invited plenary talk delivered at the International Conference on Einstein’s Legacy in the New Millennium, December 15–22, 2005, Puri, India.

Found: A Quadrillion Ways for String Theory to Make Our Universe

Circa 2019

According to string theory, all particles and fundamental forces arise from the vibrational states of tiny strings. For mathematical consistency, these strings vibrate in 10-dimensional spacetime. And for consistency with our familiar everyday experience of the universe, with three spatial dimensions and the dimension of time, the additional six dimensions are “compactified” so as to be undetectable.

Different compactifications lead to different solutions. In string theory, a “solution” implies a vacuum of spacetime that is governed by Einstein’s theory of gravity coupled to a quantum field theory. Each solution describes a unique universe, with its own set of particles, fundamental forces and other such defining properties.

Some string theorists have focused their efforts on trying to find ways to connect string theory to properties of our known, observable universe—particularly the standard model of particle physics, which describes all known particles and all their mutual forces except gravity.

With a Twist: New Composite Materials With Highly Tunable Electrical and Physical Properties

Marianne StebbinsWhat does this solve that isn’t already handled by air and water?

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Nanoparticle technology provides healthy trans, saturated fat alternative

The old adage that oil and water don’t mix isn’t entirely accurate. While it’s true that the two compounds don’t naturally combine, turning them into one final product can be done. You just need an emulsifier, an ingredient commonly used in the food industry.

Yangchao Luo, an associate professor in UConn’s College of Agriculture, Health and Natural Resources, is using an innovative emulsification process for the development of a healthier shelf-stable fat for food manufacturing.

Luo is working with something known as high internal phase Pickering emulsions (HIPEs). High internal phase means the mixture is at least 75% oil. Pickering emulsions are those that are stabilized by solid particles.

All-attosecond pump-probe spectroscopy

An international team of researchers from the Max Born Institute in Berlin, University College London and ELI-ALPS in Szeged, Hungary, has demonstrated attosecond-pump attosecond-probe spectroscopy to study non-linear multi-photon ionization of atoms. The obtained results provide insights into one of the most fundamental processes in non-linear optics.

The detailed experimental and theoretical results have been published in Optica (“Attosecond investigation of extreme-ultraviolet multi-photon multi-electron ionization”).

Fig. 1: Two intense attosecond pulse trains (white) interact with an atom, resulting in the emission of three electrons (yellow). During this process four photons (blue) are absorbed. The probability of this process can be controlled by varying the temporal and the spatial overlap between the two attosecond pulses. (Image: Balázs Major)

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