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Charge density fluctuations are observed in all families of high-critical temperature (Tc) superconducting cuprates. Although constantly found in the underdoped region of the phase diagram at relatively low temperatures, physicists are unclear how the substrates influence unusual properties of these systems. In a new study now published on Science, R. Arpaia and co-workers in the departments of microtechnology and nanoscience, the European Synchrotron, and quantum device physics in Italy, Sweden and France used resonant X-ray scattering to carefully determine the charge density modulations in Yttrium Barium Copper Oxide (YBa2Cu3O7– ẟ) and Neodymium Barium Copper Oxide (Nd1+x Ba2–x Cu3O7–ẟ) for several doping levels. The research team isolated short-range dynamic charge density fluctuations (CDFs) in addition to the previously known quasi-critical charge density waves (CDW). The results persisted well above the pseudo-gap temperature T*, which they characterized by a few milli-electron volts (meV) to spread across a large area of the phase diagram.

Cuprate high temperature superconductors (HTS) are different from the Landau Fermi liquid paradigm due to quasi-two dimensionality (2-D) of their layered structure and large electron-electron repulsion. During optimal doping and the pseudo gap state (states at which less than optimal current carrier concentrations result in anomalous electronic properties), short to medium-range charge density wave order can emerge to weakly compete with superconductivity. Physicists first developed theoretical proposals of CDW and low energy charge fluctuations after first discovering HTS. Subsequently, they developed experimental evidence in selective materials and in all cuprate families. Researchers had observed long-range tridimensional CDW (3D CDW) order inside the superconductivity dome within high magnetic fields that weaken superconductivity or in epitaxially grown (deposition of a crystalline layer on a crystalline substrate) samples.

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With apologies to “Spinal Tap,” it appears that black can, indeed, get more black.

MIT engineers report today that they have cooked up a material that is 10 times blacker than anything that has previously been reported. The material is made from vertically aligned nanotubes, or CNTs—microscopic filaments of carbon, like a fuzzy forest of tiny trees, that the team grew on a surface of chlorine-etched . The foil captures more than 99.96 percent of any incoming light, making it the blackest material on record.

The researchers have published their findings today in the journal ACS-Applied Materials and Interfaces. They are also showcasing the cloak-like material as part of a new exhibit today at the New York Stock Exchange, titled “The Redemption of Vanity.”

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Much like US corporations do now.

Debates about rights are frequently framed around the concept of legal personhood. Personhood is granted not just to human beings but also to some non-human entities, such as corporations or governments. Legal entities, aka legal persons, are granted certain privileges and responsibilities by the jurisdictions in which they are recognized, and many such rights are not available to non-person agents. Attempting to secure legal personhood is often seen as a potential pathway to get certain rights and protections for animals1, fetuses2, trees and rivers 3, and artificially intelligent (AI) agents4.

It is commonly believed that a new law or judicial ruling is necessary to grant personhood to a new type of entity. But recent legal literature 5–8 suggests that loopholes in the current law may permit legal personhood to be granted to AI/software without the need to change the law or persuade a court.

For example, L. M. LoPucki6 points out, citing Shawn Bayern’s work on conferring legal personhood on AI7, 8, “Professor Shawn Bayern demonstrated that anyone can confer legal personhood on an autonomous computer algorithm merely by putting it in control of a limited liability company (LLC). The algorithm can exercise the rights of the entity, making them effectively rights of the algorithm. The rights of such an algorithmic entity (AE) would include the rights to privacy, to own property, to enter into contracts, to be represented by counsel, to be free from unreasonable search and seizure, to equal protection of the laws, to speak freely, and perhaps even to spend money on political campaigns. Once an algorithm had such rights, Bayern observed, it would also have the power to confer equivalent rights on other algorithms by forming additional entities and putting those algorithms in control of them.”6. (See Note 1.)

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While pretty much all of the recent obsession with setting Nürburgring Ring lap record times and the rivalry between Tesla and Porsche is sort of idiotic genital-measuring, there is one foolproof way to guarantee that a record will be set: make the criteria for the record so specific that pretty much any result will set a record. That seems to be exactly what Tesla is planning by running a seven-seat Model S.

As with everything important in our world now, this all started with a tweet:

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Researchers at the University of Illinois at Urbana-Champaign have replicated one of the most well-known electromagnetic effects in physics, the Hall Effect, using radio waves (photons) instead of electric current (electrons). Their technique could be used to create advanced communication systems that boost signal transmission in one direction while simultaneously absorbing signals going in the opposite direction.

The Hall Effect, discovered in 1879 by Edwin Hall, occurs because of the interaction between charged particles and . In an electric field, negatively charged particles (electrons) experience a force opposite to the direction of the field. In a , moving electrons experience a force in the direction perpendicular to both their motion and the magnetic field. These two forces combine in the Hall Effect, where perpendicular electric and magnetic fields combine to generate an . Light isn’t charged, so regular electric and magnetic fields can’t be used to generate an analogous “current of light.” However, in a recent paper published in Physical Review Letters, researchers have done exactly this with the help of what they call “synthetic electric and magnetic fields.”

Principal investigator Gaurav Bahl’s research group has been working on several methods to improve radio and optical data transmission as well as fiber optic communication. Earlier this year, the group exploited an interaction between light and sound waves to suppress the scattering of light from material defects and published its results in Optica. In 2018, team member Christopher Peterson was the lead author in a Science Advances paper which explained a technology that promises to halve the bandwidth needed for communications by allowing an antenna to send and receive signals on the same frequency simultaneously through a process called nonreciprocal coupling.

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Industry and military scientists are moving forward in the quest to develop solid-state lasers for use as weapons by warfighters of the future

By John McHale

Even the most casual observer of military technology is aware of the U.S. Air Force’s big-ticket program-the Airborne Laser, which eats up most of the Department of Defense funding on laser technology and is nearing completion.

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