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Archive for the ‘particle physics’ category: Page 9

Sep 18, 2020

The observation of Bloch ferromagnetism in composite fermions

Posted by in categories: particle physics, quantum physics

Composite fermions are exotic quasi-particles found in interacting 2-D fermion systems at relatively large perpendicular magnetic fields. These quasi-particles, which are composed of an electron and two magnetic flux quanta, have often been used to describe a physical phenomenon known as the fractional quantum Hall effect.

Researchers at Princeton University and Pennsylvania State University recently used composite to test a theory introduced by physicist Felix Bloch almost a century ago, suggesting that at very low densities, a paramagnetic Fermi “sea” of electrons should spontaneously transition to a fully magnetized state, which is now referred to as Bloch ferromagnetism. Their paper, published in Nature Physics, provides evidence of an abrupt transition to full magnetization that is closely aligned with the state theorized by Bloch.

“Composite fermions are truly remarkable,” Mansour Shayegan, professor of Electrical Engineering at Princeton University and one of the researchers who carried out the study, told Phys.org. “They are born of interaction and magnetic flux, and yet they map such a complex system to a simple collection of quasi-particles that to a large degree behave as non-interacting and also behave as if they don’t feel the large magnetic field. One of their most interesting properties is their spin polarization.”

Sep 18, 2020

Local heating of radiation belt electrons to ultra-relativistic energies

Posted by in categories: particle physics, space

Figures 4 and 5 effectively demonstrate that local acceleration is capable of heating electrons to ~7 MeV as the phase space density profiles show signatures of local acceleration during both of the geomagnetic storms considered. The phase space density enhancements for higher energies followed the enhancements at lower energies. In Supplementary Note 8, additional analysis establishes that locally growing peaks are also observed for lower values of K, corresponding to radiation belt electrons confined closer to the equator. Furthermore, as the values of K and L* are dependent on the magnetic field model chosen, results using an additional two field models are also presented (see Supplementary Note 9) and, once again, growing peaks are observed in the radial phase space density profile. Our results demonstrate that local acceleration had a significant effect on radiation belt particles during both of the storms in October 2012, acting on electrons up to 7 MeV. In the radiation belt region, local acceleration introduces radial gradients in phase space density and so is always accompanied by both outwards and inwards radial diffusion. Locally heating electrons to ~7 MeV provides a very high energy “source population” for inwards radial diffusion and could therefore help explain the occurrence of ~10 MeV electrons in April–May 201716.

A recent study by Zhao et al.15, considered the acceleration of ultra-relativistic electrons via a statistical analysis of events during the Van Allen Probe era. The results were consistent with a two-step acceleration process, where locally heated electrons at large L*, beyond the Van Allen Probes apogee, are radially diffused inwards to reach energies of 7 MeV in the outer radiation belt. While the combination of local acceleration and radial diffusion produces 7 MeV enhancements15, the Van Allen Probe observations for the two storms shown in this study demonstrate that local acceleration can also act directly up to 7 MeV energies. The local energization mechanism responsible for generating 7 MeV electrons in the heart of the outer radiation belt, be that acceleration by chorus waves or some other process, presents an interesting focus for future research. Longer term analysis and statistical studies can be used to better understand the conditions leading to acceleration. Datasets formed via data-assimilation techniques may be useful for this purpose. Long term observations of the ultra-relativistic component of Earth’s radiation belts demonstrate that ≥7 MeV electrons are a relatively rare phenomenon, occurring far less frequently than enhancements at 1 or 2 MeV1. It therefore follows that the circumstances leading to multi-MeV enhancements could be unusual, requiring specific conditions. Our results highlight that wave-particle interactions can provide the primary acceleration mechanism for electrons up to ultra-relativistic energies, a finding applicable to magnetized plasmas throughout the solar system.

Sep 17, 2020

Looking Back on The First-Ever Photo of Quantum Entanglement

Posted by in categories: computing, particle physics, quantum physics

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This stunning image captured last year by physicists at the University of Glasgow in Scotland is the first-ever photo of quantum entanglement — a phenomenon so strange, physicist Albert Einstein famously described it as ‘spooky action at a distance’.

It might not look like much, but just stop and think about it for a second: this fuzzy grey image was the first time we’d seen the particle interaction that underpins the strange science of quantum mechanics and forms the basis of quantum computing.

Continue reading “Looking Back on The First-Ever Photo of Quantum Entanglement” »

Sep 16, 2020

Alien Technology — Almost Useless!

Posted by in categories: computing, particle physics

Returning to the theme of what might be dubbed “UFO Realism” I would like to address a topic that exercises the minds of a lot of UFO conspiracy theorists, namely, reverse engineered alien technologies.

First, is there any evidence at all that any technology we currently have has any extraterrestrial element? For example, one famous claim by Colonel Corso is that much modern technology was derived from the Roswell Incident. To quote the Wikipedia entry the list includes “…particle beam devices, fiber optics, lasers, integrated circuit chips and Kevlar material”, not to mention the transistor itself.

The initial problem with these claims is twofold.

Sep 15, 2020

Scientists discover how to trap mysterious dark matter

Posted by in categories: cosmology, particle physics

A new method promises to capture an elusive dark world particle.

Sep 15, 2020

Physicists ‘trick’ photons into behaving like electrons using a ‘synthetic’ magnetic field

Posted by in categories: futurism, particle physics

Scientists have discovered an elegant way of manipulating light using a ‘synthetic’ Lorentz force—which in nature is responsible for many fascinating phenomena including the Aurora Borealis.

A team of theoretical physicists from the University of Exeter has pioneered a new technique to create tuneable artificial magnetic fields, which enable photons to mimic the dynamics of charged particles in real magnetic fields.

The team believe the new research, published in leading journal Nature Photonics, could have important implications for future photonic devices as it provides a novel way of manipulating light below the diffraction limit.

Sep 14, 2020

Attosecond pulses reveal electronic ripples in molecules

Posted by in categories: biological, chemistry, particle physics

In the first experiment to take advantage of a new technology for producing powerful attosecond X-ray laser pulses, a research team led by scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University showed they can create electronic ripples in molecules through a process called “impulsive Raman scattering.”

Exploiting this unique interaction will allow scientists to study how electrons zipping around kick off key processes in biology, chemistry, materials science and more. The researchers described their results in Physical Review Letters.

Typically, when X-ray pulses interact with matter the X-rays cause the molecules’ innermost “core” electrons to jump to higher energies. These core-excited states are highly unstable, decaying in just millionths of a billionth of a second. In a majority of X-ray experiments, that’s how the story ends: The excited electrons quickly return to their rightful places by transferring their energy to a neighboring electron, forcing it out of the atom and producing a charged ion.

Sep 13, 2020

Spin-Based Quantum Computing Breakthrough: Physicists Achieve Tunable Spin Wave Excitation

Posted by in categories: computing, nanotechnology, particle physics, quantum physics

Physicists from MIPT and the Russian Quantum Center, joined by colleagues from Saratov State University and Michigan Technological University, have demonstrated new methods for controlling spin waves in nanostructured bismuth iron garnet films via short laser pulses. Presented in Nano Letters, the solution has potential for applications in energy-efficient information transfer and spin-based quantum computing.

A particle’s spin is its intrinsic angular momentum, which always has a direction. In magnetized materials, the spins all point in one direction. A local disruption of this magnetic order is accompanied by the propagation of spin waves, whose quanta are known as magnons.

Unlike the electrical current, spin wave propagation does not involve a transfer of matter. As a result, using magnons rather than electrons to transmit information leads to much smaller thermal losses. Data can be encoded in the phase or amplitude of a spin wave and processed via wave interference or nonlinear effects.

Continue reading “Spin-Based Quantum Computing Breakthrough: Physicists Achieve Tunable Spin Wave Excitation” »

Sep 11, 2020

Magnonic nano-fibers opens the way towards new type of computers

Posted by in categories: computing, nanotechnology, neuroscience, particle physics

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Magnetism offers new ways to create more powerful and energy-efficient computers, but the realization of magnetic computing on the nanoscale is a challenging task. A critical advancement in the field of ultralow power computation using magnetic waves is reported by a joint team from Kaiserslautern, Jena and Vienna in the journal Nano Letters.

A local disturbance in the magnetic order of a magnet can propagate across a material in the form of a wave. These waves are known as spin waves and their associated quasi-particles are called magnons. Scientists from the Technische Universität Kaiserslautern, Innovent e. V. Jena and the University of Vienna are known for their expertise in the called ‘magnonics,’ which utilizes magnons for the development of novel types of computers, potentially complementing the conventional electron-based processors used nowadays.

Continue reading “Magnonic nano-fibers opens the way towards new type of computers” »

Sep 10, 2020

Quirky response to magnetism presents quantum physics mystery

Posted by in categories: particle physics, quantum physics

The search is on to discover new states of matter, and possibly new ways of encoding, manipulating, and transporting information. One goal is to harness materials’ quantum properties for communications that go beyond what’s possible with conventional electronics. Topological insulators—materials that act mostly as insulators but carry electric current across their surface—provide some tantalizing possibilities.

“Exploring the complexity of topological materials—along with other intriguing emergent phenomena such as and superconductivity—is one of the most exciting and challenging areas of focus for the materials science community at the U.S. Department of Energy’s Brookhaven National Laboratory,” said Peter Johnson, a senior physicist in the Condensed Matter Physics & Materials Science Division at Brookhaven. “We’re trying to understand these topological insulators because they have lots of potential applications, particularly in quantum information science, an important new area for the division.”

For example, materials with this split insulator/conductor personality exhibit a separation in the energy signatures of their surface electrons with opposite “spin.” This quantum property could potentially be harnessed in “spintronic” devices for encoding and transporting information. Going one step further, coupling these electrons with magnetism can lead to novel and exciting phenomena.

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