Toggle light / dark theme

Abstract: Scientists have looked for different ways to force hydrogen into a metallic state for decades. A metallic state of hydrogen is a holy grail for materials science because it could be used for superconductors, materials that have no resistance to the flow of electrons, which increases electricity transfer efficiency many times over. For the first time researchers, led by Carnegie’s Viktor Struzhkin, have experimentally produced a new class of materials blending hydrogen with sodium that could alter the superconductivity landscape and could be used for hydrogen-fuel cell storage. The research is published in Nature Communications.

It had been predicted that certain hydrogen-rich compounds consisting of multiple atoms of hydrogen with so-called alkali metals like lithium, potassium or sodium, could provide a new chemical means to alter the compound’s electronic structure. This, in turn, may lead the way to metallic high-temperature superconductors.

“The challenge is temperature,” explained Struzhkin. “The only superconductors that have been produced can only exist at impractically cold temperatures. In recent years, there have been predictions of compounds with several atoms of hydrogen coupled with alkali metals that could exist at more practical temperatures. They are theorized to have unique properties useful to superconductivity.”

Read more

Among the intriguing issues in plasma physics are those surrounding X-ray pulsars—collapsed stars that orbit around a cosmic companion and beam light at regular intervals, like lighthouses in the sky. Physicists want to know the strength of the magnetic field and density of the plasma that surrounds these pulsars, which can be millions of times greater than the density of plasma in stars like the sun.

Researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have developed a theory of waves that can infer these properties in greater detail than in standard approaches. The new research analyzes the plasma surrounding the pulsar by coupling Einstein’s theory of relativity with , which describes the motion of subatomic particles such as the atomic nuclei—or ions—and electrons in plasma. Supporting this work is the DOE Office of Science.

Quantum field theory

The key insight comes from , which describes charged particles that are relativistic, meaning that they travel at near the speed of light. “Quantum theory can describe certain details of the propagation of waves in plasma,” said Yuan Shi, a graduate student in the Princeton Program in Plasma Physics and lead author of a paper published July 29 in the journal Physical Review A. Understanding the interactions behind the propagation can then reveal the composition of the plasma.

Read more

If biochemists had access to a quantum computer, they could perfectly simulate the properties of new molecules to develop drugs in ways that would take today’s fastest computers decades. A new device takes us closer to providing such a computer. The device successfully traps, detects, and manipulates an ensemble of electrons above the surface of superfluid helium. The system integrates a nanofluidic channel with a superconducting circuit.

Because they are so small, electrons normally interact weakly with electrical signals. The new device, however, gives the electron more time to interact, and it is this setup that makes it possible to build a qubit, the quantum computing equivalent of a bit. Quantum computers could provide the necessary computing power to model extremely large and complex situations in physics, biology, weather systems and many others.

While isolated electrons in a vacuum can store quantum information nearly perfectly, in real materials, the movements of surrounding atoms disturbs them, eventually leading to the loss of information. This work is a step towards realizing isolated, trapped single electrons by taking advantage of the unique relationship existing between electrons and superfluid helium. Electrons will levitate just above the surface of helium, about 10 nanometers away, insensitive to the atomic fluctuations below. While this effect has been known, holding them in a superconducting device structure has not been demonstrated before this work. At the heart of this new technology is a resonator based on circuit quantum electrodynamics (cQED) architecture, which provides a path to trap electrons above helium and detect the spins of the electrons. Because they are so small, electrons normally interact only very weakly with electrical signals.

Read more

In December of last year, scientists at the Large Hadron Collider in Europe announced startling results hinting at the existence of an undiscovered subatomic particle—one with a mass six times heavier than the Higgs boson, the particle that made headlines in 2012.

The evidence is still thin, but if more data confirm the finding, it could sharpen humankind’s understanding of the building blocks of the universe.

“This was a very surprising announcement and a puzzle at the same time, because the lifetime and mass of the particle could reveal something else beyond simply one extra particle, if it turns out to be a real signal,” said Kyoungchul “K.C.” Kong, associate professor of physics and astronomy at the University of Kansas. “Yet we do not claim this as a discovery, and we need more data.”

Read more

“Another very good test some readers may want to look up… is the Casimir effect, where forces between metal plates in empty space are modified by the presence of virtual particles.” –Gordon Kane

If you ask what the zero-point energy of space itself is, you can sum up all of the quantum fluctuations you can that arise in quantum field theory, and arrive at an absurd answer: 120 orders of magnitude greater than the observed. Yet if you assume that there’s an incredible cancellation and you get exactly zero, that removes the one thing our Universe needs to explain its expansion: dark energy.

Read more

The realization of reconfigurable modular microrobots could aid drug delivery and microsurgery by allowing a single system to navigate diverse environments and perform multiple tasks. So far, microrobotic systems are limited by insufficient versatility; for instance, helical shapes commonly used for magnetic swimmers cannot effectively assemble and disassemble into different size and shapes. Here by using microswimmers with simple geometries constructed of spherical particles, we show how magnetohydrodynamics can be used to assemble and disassemble modular microrobots with different physical characteristics. We develop a mechanistic physical model that we use to improve assembly strategies. Furthermore, we experimentally demonstrate the feasibility of dynamically changing the physical properties of microswimmers through assembly and disassembly in a controlled fluidic environment. Finally, we show that different configurations have different swimming properties by examining swimming speed dependence on configuration size.

Read more

Finally, portable thermal imaging devices could be here soon.


The primary source of infrared radiation is heat—the radiation produced by the thermal motion of charged particles in matter, including the motion of the atoms and molecules in an object. The higher the temperature of an object, the more its atoms and molecules vibrate, rotate, twist through their vibrational modes, the more infrared radiation they radiate. Because infrared detectors can be “blinded” by their own heat, high-quality infrared sensing and imaging devices are usually cooled down, sometimes to just a few degrees above absolute zero. Though they are very sensitive, the hardware required for cooling renders these instruments less-than-mobile, energy-inefficient and limits in-the-field applications.

A paper published this week in the journal Optics Express, from The Optical Society (OSA), describes a new type of portable, field-friendly, mid-infrared detector that operates at room temperature. Room-temperature operation, notes Andreas Harrer of the TU-Wien Center for Micro- and Nanostructures, Austria and the first author of the paper, “is essential for detectors to be energy-efficient enough for portable and handheld applications. We want to pave the way to an infrared-detection technology which is flexible in design and meets all requirements for compact integrated field-applicable detection systems.”

The type of instrument developed by Harrer and his colleagues is known as a quantum cascade detector, or QCD. A QCD is a high-speed detector composed of semiconductor devices that sense specific wavelengths of infrared light and convert that light into proportionate electrical signals. A unique aspect of the design described by Harrer and his colleagues is that it consists of an 8 x 8 array of pixels, each approximately 110 microns square. Tuning is achieved by specifically adjusting the well and the barrier dimensions to a wavelength of 4.3 microns.

Read more

Excellent article on improving crystalized formations & usage.


According to conventional understanding, if the interactions are isotropic (where all spin directions are possible), this phenomenon can occur if the spins are arranged in triangular geometries and the interactions between them are antiferromagnetic favouring antiparallel alignment of the spins. For three atoms forming the corners of a triangle, the electronic spin of one atom cannot simultaneously be oriented antiparallel to those on both the other two atoms. In real materials that contain triangular units coupled by antiferromagnetic interactions this “frustration” can prevent the spins from coming to rest in a particular orientation even at absolute zero temperature, instead they move collectively like atoms in a liquid. By contrast, ferromagnetic interactions do not give rise to frustration in isotropic magnets because mutually parallel alignment of the spins can always occur. For these reasons, only a few isotropic materials have been proposed as spin liquid candidates.

Monocrystals with complex magnetic interactions

Now a team headed by Prof. Bella Lake has produced and investigated the first monocrystals of calcium-chromium oxide (Ca10Cr7O28). Calcium-chromium oxide is made up of what are known as Kagomé lattices — reminiscent of the pattern of triangles and hexagons woven in Japanese basketry. As a result, a complex set of isotropic magnetic interactions develop in this material, consisting of not only anti-ferromagnetic interactions but also much stronger ferromagnetic interactions that according to conventional understanding should prevent the existence of spin liquid behavior. Magnetic and Neutron scattering experiments conducted in Germany, France, England, and the USA, as well as muon spectroscopy experiments performed in Switzerland have however shown that the spins in these samples retain their collective motion even at temperatures as low as 20 millikelvin and behave like a quantum spin liquid.

Read more