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Category: particle physics – Page 430

Circa 2018

If you’ve been a grunt, then you probably have a love-hate relationship with body armor. You love having it in a firefight — it can save your life by stopping or slowing bullets and fragments — but you hate how heavy it is — it’s often around 25 pounds for the armor and outer tactical vest (more if you add the plate inserts to stop up to 7.62mm rounds). It’s bulky — and you really can’t move as well in it. In fact, in one firefight, a medic removed his body armor to reach wounded allies, earning a Distinguished Service Cross.

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Circa 1994

It is generally accepted that structure formed in the matter dominated Universe, for obvious reasons. In this paper, we would like to suggest an alternate theory: that structure could have formed in the radiation dominated Universe if it was “protected” from destruction. This protection is envisioned as a “crystal”, of sorts, made up of primordial black holes (PBH’s), which form a cavitation into which any matter particles in the nucleosynthesis period of the Universe (around 100 seconds after the Big Bang) could have taken refuge. A sort of oasis in a sea of radiation. Such a scenario could solve several problems in cosmology, namely: how matter got a foot-hold over anti-matter in the Universe; the structure/galaxy formation problem; and possibly suggest ideas on the gamma-ray count and distribution.

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A team of researchers affiliated with several institutions in the Republic of Korea has found that it is possible to replace chemical functional groups with a gold electrode to control the reactivity of a molecule. In their paper published in the journal Science, the group describes attaching target molecules to a gold electrode to change the properties of immobilized molecules and how their technique performed when used to rate changes in the hydrolysis of certain esters.

In chemistry, are assortments of atoms that together work to attach carbon skeletons in . All organic have their own unique functional groups, which play an important role in the formation of molecules. Functional groups can also donate or take away electrons when one molecule comes into contact with another, which is how many occur.

Chemists have found that they can tinker with functional groups to speed up or slow down reactions to suit their needs, and because of that, functional groups play an important role in chemical synthesis. Unfortunately, developing reactions to produce desired products using functional groups has proven to be slow and difficult work. In this new effort, the researchers have found a way to replace the use of functional groups with a gold electrode to make the work easier. They simply attached molecules to a gold electrode and turned on the electricity. The technique allowed for more control over reactions by varying the amount of electricity supplied to the electrode. In such a capacity, the electrode was able to work as a “universal functional group” to inhibit or propel reactions when the researchers manipulated the amount of electricity applied to the electrode.

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Since the discovery of graphene more than 15 years ago, researchers have been in a global race to unlock its unique properties. Not only is graphene—a one-atom-thick sheet of carbon arranged in a hexagonal lattice—the strongest, thinnest material known to man, it is also an excellent conductor of heat and electricity.

Now, a team of researchers at Columbia University and the University of Washington has discovered that a variety of exotic electronic states, including a rare form of magnetism, can arise in a three-layer structure.

The findings appear in an article published Oct. 12 in Nature Physics.

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Physics theory suggests that exotic excitations can exist in the form of bound states confined in the proximity of topological defects, for instance, in the case of Majorana zero modes that are trapped in vortices within topological superconducting materials. Better understanding these states could aid the development of new computational tools, including quantum technologies.

One phenomenon that has attracted attention over the past few years is “braiding,” which occurs when electrons in particular states (i.e., Majorana fermions) are braided with one another. Some physicists have theorized that this phenomenon could enable the development of a new type of quantum technology, namely topological quantum computers.

Researchers at Pennsylvania State University, University of California-Berkeley, Iowa State University, University of Pittsburgh, and Boston University have recently tested the hypothesis that braiding also occurs in particles other than electrons, such as photons (i.e., particles of light). In a paper published in Nature Physics, they present the first experimental demonstration of braiding using photonic topological zero modes.

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As tiny particles traveling at the speed of light, it’s going to take a serious machine to capture photons in action, and an international team of researchers have just pieced together one that is very much up for the job. Dubbed the world’s fastest UV camera, the device is capable of capturing ultra-fast events lasting just a picosecond, quick enough to see UV photons fly through the air in real time.

The device is the handiwork of Canada’s Institut National de la Recherche Scientifique (National Institute of Research) and goes by the name of UV-CUP (compressed ultrafast photography). CUP is an emerging imaging technique that has been used to capture ultrafast events at speeds measured in trillions of frames a second, but has so far been limited to visible and near-infrared wavelengths.

“Many phenomena that occur on very short time scales also take place on a very small spatial scale,” says Jinyang Liang, who led the study. “To see them, you need to sense shorter wavelengths. Doing this in the UV or even X-ray ranges is a remarkable step toward this goal.”

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Quantum mechanics, the physics of atoms and subatomic particles, can be strange, especially compared to the everyday physics of Isaac Newton’s falling apples. But this unusual science is enabling researchers to develop new ideas and tools, including quantum computers, that can help demystify the quantum realm and solve complex everyday problems.

That’s the goal behind a new U.S. Department of Energy Office of Science (DOE-SC) grant, awarded to Michigan State University (MSU) researchers, led by physicists at Facility for Rare Isotope Beams (FRIB). Working with Los Alamos National Laboratory, the team is developing algorithms – essentially programming instructions – for quantum computers to help these machines address problems that are difficult for conventional computers. For example, problems like explaining the fundamental quantum science that keeps an atomic nucleus from falling apart.

The $750,000 award, provided by the Office of Nuclear Physics within DOE-SC, is the latest in a growing list of grants supporting MSU researchers developing new quantum theories and technology.

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“In previous work, the researchers discovered that when optical matter is exposed to circularly polarized light, it rotates as a rigid body in the direction opposite the polarization rotation. In other words, when the incident light rotates one way the optical matter array responds by spinning the other. This is a manifestation of “negative torque”. The researchers speculated that a machine could be developed based on this new phenomenon.

In the new work, the researchers created an optical matter machine that operates much like a mechanical machine based on interlocking gears. In such machines, when one gear is turned, a smaller interlocking gear will spin in the opposite direction. The optical matter machine uses circularly polarized light from a laser to create a nanoparticle array that acts like the larger gear by spinning in the optical field. This “optical matter gear” converts the circularly polarized light into orbital, or angular, momentum that influences a nearby probe particle to orbit the nanoparticle array (the gear) in the opposite direction.”

Researchers have developed a tiny new machine that converts laser light into work. These optically powered machines self-assemble and could be used for nanoscale manipulation of tiny cargo for applications such as nanofluidics and particle sorting.

“Our work addresses a long-standing goal in the nanoscience community to create self-assembling that can perform work in conventional environments such as room temperature liquids,” said research team leader Norbert F. Scherer from the University of Chicago.

Scherer and colleagues describe the new nanomachines in Optica. The machines are based on a type of matter known as optical matter in which metal nanoparticles are held together by light rather than the that hold together the atoms that make up typical matter.

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Based on optical matter, new machines could be used to move and manipulate tiny particles.

Researchers have developed a tiny new machine that converts laser light into work. These optically powered machines self-assemble and could be used for nanoscale manipulation of tiny cargo for applications such as nanofluidics and particle sorting.

“Our work addresses a long-standing goal in the nanoscience community to create self-assembling nanoscale machines that can perform work in conventional environments such as room temperature liquids,” said research team leader Norbert F. Scherer from the University of Chicago.

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“At first, we thought it was absurd. How else could you respond to the idea that black holes generate swirling clouds of planet-sized particles that could be the dark matter thought to hold galaxies together? We tend to think about particles as being tiny but, theoretically, there is no reason they can’t be as big as a galaxy,” said theoretical physicist Asimina Arvanitaki, at the Perimeter Institute for Theoretical Physics referring to the heated debate about the standard model for dark matter that proposes that it is ‘cold,’ meaning that the particles move slowly compared to the speed of light which is tied to the mass of dark matter particles. The lower the mass of the particle, the ‘warmer’ it is and the faster it will move.

On January 9, NASA physicists using the Hubble Space Telescope reported that although the type of particle that makes up dark matter is still a mystery, a compelling observational test for the cold dark matter passed “with flying colors,” The NASA team used a new “cosmic magnifying glasses” technique that found that dark matter forms much smaller clumps than previously known, confirming one of the fundamental predictions of the widely accepted “cold dark matter” theory.

Physicists at the University of California, Davis, taking the temperature of dark matter, the mysterious substance that makes up about a quarter of our universe now report that the model of cold (more massive) dark matter holds at very large scales” said Chris Fassnacht, a physics professor at UC Davis, “but doesn’t work so well on the scale of individual galaxies.” That’s led to other models including ‘warm’ dark matter with lighter, faster-moving particles and ‘hot’ dark matter with particles moving close to the speed of light that have been ruled out by observations.

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