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Category: particle physics

Entanglement is one of the strangest phenomena predicted by quantum mechanics, the theory that underlies most of modern physics. It says that two particles can be so inextricably connected that the state of one particle can instantly influence the state of the other, no matter how far apart they are.

Just one century ago, was at the center of intense theoretical debate, leaving scientists like Albert Einstein baffled. Today, however, entanglement is accepted as a fact of nature and is actively being explored as a resource for future technologies including quantum computers, quantum communication networks, and high-precision quantum sensors.

Entanglement is also one of nature’s most elusive phenomena. Producing entanglement between particles requires that they start out in a highly ordered state, which is disfavored by thermodynamics, the process that governs the interactions between heat and other forms of energy. This poses a particularly formidable challenge when trying to realize entanglement at the macroscopic scale, among huge numbers of particles.

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Today’s particle accelerators are massive machines, but physicists have been working on shrinking them down to tabletop scales for years. The Gordon and Betty Moore Foundation just awarded a $13.5 million grant to Stanford University to develop a working “accelerator on a chip” the size of a shoebox over the next five years.

The international collaboration will build on prior experiments by physicists at SLAC/Stanford and Germany’s Friedrich-Alexander University in Erlangen-Nuremberg. If successful, the prototype could usher in a new generation of compact particle accelerators that could fit on a laboratory bench, with potential applications in medical therapies, x-ray imaging, and even security scanner technologies.

The idea is to “do for particle accelerators what the microchip industry did for computers,” SLAC National Accelerator Laboratory physicist Joel England told Gizmodo. Computers used to fill entire rooms back when they relied on bulky vacuum tube technology. The invention of the transistor and subsequent development of the microchip made it possible to shrink computers down to laptop and cell phone scales. England envisions a day when we might be able to build a handheld particle accelerator, although “there’d be radiation issues, so you probably wouldn’t want to hold one in your hand.”

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An international team of physicists including theorists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory has published the first calculation of direct “CP” symmetry violation—how the behavior of subatomic particles (in this case, the decay of kaons) differs when matter is swapped out for antimatter. Should the prediction represented by this calculation not match experimental results, it would be conclusive evidence of new, unknown phenomena that lie outside of the Standard Model—physicists’ present understanding of the fundamental particles and the forces between them.

The current result—reported in the November 20 issue of Physical Review Letters —does not yet indicate such a difference between experiment and theory, but scientists expect the precision of the calculation to improve dramatically now that they’ve proven they can tackle the task. With increasing precision, such a difference—and new physics—might still emerge.

“This so called ‘direct’ symmetry violation is a tiny effect, showing up in just a few particle decays in a million,” said Brookhaven physicist Taku Izubuchi, a member of the team performing the calculation. Results from the first, less difficult part of this calculation were reported by the same group in 2012. However, it is only now, with completion of the second part of this calculation—which was hundreds of times more difficult than the first—that a comparison with the measured size of direct CP violation can be made. This final part of the calculation required more than 200 million core processing hours on supercomputers, “and would have required two thousand years using a laptop,” Izubuchi said.

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(Phys.org)—The fundamental constants of nature—such as the speed of light, Planck’s constant, and Newton’s gravitational constant—are thought to be constant in time, as their name suggests. But scientists have questioned this assumption as far back as 1937, when Paul Dirac hypothesized that Newton’s gravitational constant might decrease over time.

Now in a new paper published in Physical Review Letters, Yevgeny V. Stadnik and Victor V. Flambaum at the University of New South Wales in Sydney, Australia, have theoretically shown that can cause the fundamental constants of nature to slowly evolve as well as oscillate due to oscillations in the dark matter field. This idea requires that the weakly interacting dark matter particles be able to interact a small amount with particles, which the scientists show is possible.

In their paper, the scientists considered a model in which dark matter is made of weakly interacting, low-mass particles. In the early Universe, according to the model, large numbers of such dark matter particles formed an oscillating field. Because these particles interact so weakly with standard model particles, they could have survived for billions of years and still exist today, forming what we know as dark matter.

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Dark matter is called “dark” for a good reason. Although they outnumber particles of regular matter by more than a factor of 10, particles of dark matter are elusive. Their existence is inferred by their gravitational influence in galaxies, but no one has ever directly observed signals from dark matter. Now, by measuring the mass of a nearby dwarf galaxy called Triangulum II, Assistant Professor of Astronomy Evan Kirby may have found the highest concentration of dark matter in any known galaxy.

Triangulum II is a small, faint galaxy at the edge of the Milky Way, made up of only about 1,000 stars. Kirby measured the mass of Triangulum II by examining the velocity of six stars whipping around the galaxy’s center. “The galaxy is challenging to look at,” he says. “Only six of its stars were luminous enough to see with the Keck telescope.” By measuring these stars’ velocity, Kirby could infer the gravitational force exerted on the stars and thereby determine the mass of the galaxy.

“The total mass I measured was much, much greater than the mass of the total number of stars—implying that there’s a ton of densely packed dark matter contributing to the total mass,” Kirby says. “The ratio of dark matter to luminous matter is the highest of any galaxy we know. After I had made my measurements, I was just thinking—wow.”

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What seemed to be flaws in the structure of a mystery metal may have given physicists a glimpse into as-yet-undiscovered laws of the universe.

The qualities of a high-temperature superconductor — a compound in which electrons obey the spooky laws of quantum physics, and flow in perfect synchrony, without friction — appear linked to the fractal arrangements of seemingly random oxygen atoms.

Those atoms weren’t thought to matter, especially not in relation to the behavior of individual electrons, which exist at a scale thousands of times smaller. The findings, published Aug. 12 in Nature, are a physics equivalent of discovering a link between two utterly separate dimensions.

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It’s made of just 244 atoms.

In the nearly 400 years since the first submarine was invented, these underwater machines have become incredibly sophisticated. They’re armed and they’re really stealthy. We’re even planning on sending subs to oceans on distant moons. Trippy.

But now, a submarine is going where no submarine has gone before. To the molecular level. In a paper published this month in NanoLetters, researchers announced that they’ve invented a submarine so small that it’s made out of a single molecule.

The submarine is made of just 244 atoms, and can move through fluids with molecules of approximately the same size all around it.

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One of the weirdest aspects of quantum mechanics is entanglement, because two entangled particles affecting each other across vast distances seems to violate a fundamental principle of physics called locality: things that happen at a particular point in space can only influence the points closest to it. But what if locality — and space itself — is not so fundamental after all? Author George Musser explores the implications in his new book, Spooky Action At a Distance.

When the philosopher Jenann Ismael was ten years old, her father, an Iraqi-born professor at the University of Calgary, bought a big wooden cabinet at an auction. Rummaging through it, she came across an old kaleidoscope, and she was entranced. For hours she experimented with it and figured out how it worked. “I didn’t tell my sister when I found it, because I was scared she’d want it,” she recalls.

As you peer into a kaleidoscope and turn the tube, multicolored shapes begin to blossom, spin and merge, shifting unpredictably in seeming defiance of rational explanation, almost as if they were exerting spooky action at a distance on one another. But the more you marvel at them, the more regularity you notice in their motion. Shapes on opposite sides of your visual field change in unison, and their symmetry clues you in to what’s really going on: those shapes aren’t physical objects, but images of objects — of shards of glass that are jiggling around inside a mirrored tube.

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SANTA CLARA, California — Robotic spacecraft may ride the solar wind toward interstellar space at unprecedented speeds a decade or so from now.

Researchers are developing an “electric sail” (e-sail) propulsion system that would harness the solar wind, the stream of protons, electrons and other charged particles that flows outward from the sun at more than 1 million mph (1.6 million kilometers per hour).

“It looks really, really promising for ultra-deep-space exploration,” Les Johnson, of NASA’s Marshall Space Flight Center in Huntsville, Alabama, said of the e-sail concept here at the 100-Year Starship Symposium on Oct. 30. [Superfast Spacecraft Propulsion Concepts (Images)].

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