Lifeboat Foundation

Circa 2014 essentially this could make endless computer chips from light.

Princeton researchers have managed to cause light to behave like a crystal within a specialized computer chip, according to a recent paper. This is the first time anyone has accomplished this effect in a lab.

Here’s why it’s so hard: Atoms can easily form solids, liquids, and gasses, because when they come into contact they push and pull on each other. That push and pull forms the underlying structure of all matter. Light particles, or photons, do not typically interact with one another, according to Dr. Andrew Houck, a professor of electrical engineering at Princeton and an author on the study. The trick of this research was forcing them to do just that.

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The New York Times Apr 09, 2021 17:29:04 IST

Evidence is mounting that a tiny subatomic particle seems to be disobeying the known laws of physics, scientists announced Wednesday, a finding that would open a vast and tantalizing hole in our understanding of the universe. The result, physicists say, suggests that there are forms of matter and energy vital to the nature and evolution of the cosmos that are not yet known to science.

“This is our Mars rover landing moment,” said Chris Polly, a physicist at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Illinois, who has been working toward this finding for most of his career.

Physicists have seen signs that a mystery force is interacting with other particles in a manner never witnessed before. It may explain some of the deepest physics puzzles.

Two teams of researchers have independently found that there exists a certain type of graphene system where electrons freeze as the temperature rises. The first team, with members from Israel, the U.S. and Japan, found that placing one layer of graphene atop another and then twisting the one on top resulted in a graphene state in which the electrons would freeze as temperatures rose. And in attempting to explain what they observed, they discovered that the entropy of the near-insulating phase was approximately half of what would be expected from free-electron spins. The second team, with members from the U.S., Japan and Israel, found the same graphene system and in their investigation to understand their observations, they noted that a large magnetic moment arose in the insulator. Both teams have published their results in the journal Nature. Biao Lian with Princeton University has published a News and Views piece outlining the work by both teams in the same journal issue.

As temperatures around most substances rise, the particles they are made of are excited. This results in solids melting to liquids and liquids turning to a gas. This is explained by thermodynamics—higher temperatures lead to more entropy, which is a description of disorder. In this new effort, both teams found an exception to this rule—a graphene system in which electrons freeze as the temperature rises.

The graphene system was very simple. Both teams simply laid one sheet of graphene on top of another and then twisted the top sheet very slightly. But it had to be twisted at what they describe as the “magic angle,” describing a twist of just 1 degree. The moiré pattern that resulted led to lower velocity of the electrons in the system, which in turn led to more resistance, bringing the system close to being an insulator.

It’s not the next Higgs boson — yet. But the best explanation, physicists say, involves forms of matter and energy not currently known to science.

Researchers have used a quantum mechanical property to overcome some of the limitations of conventional holograms. The new approach, detailed in Nature Physics, employed quantum entanglement, allowing two photons to become a single “non-local particle.” A series of entangled photon pairs is key to producing new and improved holograms.

Classical holograms work by using a single light beam split into two. One beam is sent towards the object you’re recreating and is reflected onto a special camera. The second beam is sent directly onto the camera. By measuring the differences in light, its phase, you can reconstruct a 3D image. A key property in this is the wave’s coherence.

The quantum hologram shares some of these principles but its execution is very different. It starts by splitting a laser beam in two, but these two beams will not be reunited. The key is in the splitting. As you can see in the image below, the blue laser hits a nonlinear crystal, which creates two beams made of pairs of entangled photons.

PARIS: Scientists believe they may have discovered a “brand-new force of nature” at CERN’s Large Hadron Collider that could explain why certain atomic particles behave unexpectedly and which may transform our understanding the rudiments of physics.

Authors of the research said this week that their results should “get physicists’ hearts beating just a little faster” after they discovered evidence of a “brand-new” type of particle.

Since its inception over a decade ago, the Large Hadron Collider (LHC) has sought to delve into the secrets of the universe by studying the smallest discreet particles of matter as they collide at nearly the speed of light.

This is the best estimate scientists have made for the size of the invisible Higgs sector. The next step is to collect more data and hone their techniques to narrow in on these invisible decays.

“It’s like looking at something very small,” Rifki says. “Right now, we can’t see anything other than what we already know. But that doesn’t mean there is nothing new there. It could just mean that we need a more powerful lens.”

Lindert sees this collaboration as a good example of what theorists and experimentalists can accomplish when they combine their skills and work together.

A step towards ultra-precise measurements of antihydrogen.

These two constraints are so fundamental that it would be difficult to formulate a consistent understanding of nature without them. Nevertheless, it is worth testing whether they really hold up in ultra-precise measurements carried out using the most modern technologies, because any deviation, however small, would force scientists to radically rethink the basis of our theories of physics. Writing in Nature, Baker et al.¹ (members of the ALPHA collaboration) report a major step towards this goal. They have slowed down atoms of antihydrogen — the antimatter counterpart of hydrogen — to unprecedentedly low velocities by bathing them in a beam of ultraviolet laser light. This could allow measurements of the atoms to be made with exceptionally high precision.

Antihydrogen is the simplest stable atom that consists only of antimatter particles, namely an antiproton and an antielectron (a positron). Measurements of antihydrogen therefore provide an ideal way to test the symmetry between matter and antimatter, but such experiments present formidable obstacles. In 1995, 11 antihydrogen atoms were produced from reactions in a particle accelerator at CERN, Europe’s particle-physics laboratory near Geneva, Switzerland, and hurtled down a 10-metre-long vacuum tube at nine-tenths of the speed of light². Each atom existed for barely a few tens of nanoseconds before being destroyed by striking a particle detector.

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