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Researchers from Tokyo Metropolitan University have developed a new technology which allows non-contact manipulation of small objects using sound waves. They used a hemispherical array of ultrasound transducers to generate a 3D acoustic field that stably trapped and lifted a small polystyrene ball from a reflective surface. Their technique employs a method similar to laser trapping in biology, but adaptable to a wider range of particle sizes and materials.

The ability to move objects without touching them might sound like magic, but in the world of biology and chemistry, technology known as optical trapping has been helping scientists use light to move microscopic objects around for many years. In fact, half of the 2018 Nobel Prize for Physics, awarded to Arthur Ashkin (1922–2020) was in recognition of the remarkable achievements of this technology. But the use of laser light is not without its failings, particularly the limits placed on the properties of the objects which can be moved.

Enter acoustic trapping, an alternative that uses sound instead of optical waves. Sound waves may be applied to a wider range of object sizes and materials, and successful manipulation is now possible for millimeter-sized particles. Though they haven’t been around for as long as their optical counterparts, acoustic levitation and manipulation show exceptional promise for both lab settings and beyond. But the technical challenges that need to be surmounted are considerable. In particular, it is not easy to individually and accurately control vast arrays of ultrasound transducers in real time, or to get the right sound fields to lift objects far from the transducers themselves, particularly near surfaces that reflect sound.

Physicists at CERN have discovered an exotic new particle that’s quite charming. Known as T_cc⁺, the particle belongs to a rare class called tetraquarks, and its unusual composition makes it the longest-lived exotic hadron found so far.

Matter is made up of fundamental particles called quarks, which come in six “flavors”: up, down, strange, charm, top and bottom. These quarks group together in different ways to make up different types of matter – baryons like protons and neutrons are made up of several quarks, while mesons are formed from quarks paired with antiquarks, their antimatter equivalents.

Baryons are usually comprised of two or three quarks, but exotic baryons made up of four or five have been discovered in recent years, after being theorized for decades. T_cc⁺ is one of these unusual particles with four quarks, known as a tetraquark.

In a mind-mending experiment, scientists transformed purified water into metal for a few fleeting seconds, thus allowing the liquid to conduct electricity.

Unfiltered water can already conduct electricity — meaning negatively charged electrons can easily flow between its molecules — because unfiltered water contains salts, according to a statement about the new study. However, purified water contains only water molecules, whose outermost electrons remain bound to their designated atoms, and thus, they can’t flow freely through the water.

Quarks are the fundamental building blocks from which matter is constructed. They combine to form hadrons, namely baryons, such as the proton and the neutron, which consist of three quarks, and mesons, which are formed as quark-antiquark pairs. In recent years a number of so-called exotic hadrons—particles with four or five quarks, instead of the conventional two or three—have been found. Today’s discovery is of a particularly unique exotic hadron, an exotic exotic hadron if you like.

The new particle contains two charm quarks and an up and a down antiquark. Several tetraquarks have been discovered in recent years (including one with two charm quarks and two charm antiquarks), but this is the first one that contains two charm quarks, without charm antiquarks to balance them. Physicists call this “open charm” (in this case, “double open charm”). Particles containing a charm quark and a charm antiquark have “hidden charm”—the charm quantum number for the whole particle adds up to zero, just like a positive and a negative electrical charge would do. Here the charm quantum number adds up to two, so it has twice the charm!

The quark content of T_cc⁺, has other interesting features besides being open charm. It is the first particle to be found that belongs to a class of tetraquarks with two heavy quarks and two light antiquarks. Such particles decay by transforming into a pair of mesons, each formed by one of the heavy quarks and one of the light antiquarks. According to some theoretical predictions, the mass of tetraquarks of this type should be very close to the sum of masses of the two mesons. Such proximity in mass makes the decay “difficult,” resulting in a longer lifetime of the particle, and indeed T_cc⁺, is the longest-lived exotic hadron found to date.

Some of the greatest mysteries in cosmology revolve around antimatter, and it’s hard to study because it’s rare and hard to produce in the lab. Now a team of physicists has outlined a relatively simple new way to create antimatter, by firing two lasers at each other to reproduce the conditions near a neutron star, converting light into matter and antimatter.

In principle, antimatter sounds simple – it’s just like regular matter, except its particles have the opposite charge. That basic difference has some major implications though: if matter and antimatter should ever meet, they will annihilate each other in a burst of energy. In fact, that should have destroyed the universe billions of years ago, but obviously that didn’t happen. So how did matter come to dominate? What tipped the scales in its favor? Or, where did all the antimatter go?

Unfortunately, antimatter’s scarcity and instability make it difficult to study to help answer those questions. It’s naturally produced under extreme conditions, such as lightning strikes, or near black holes and neutron stars, and artificially in huge facilities like the Large Hadron Collider.

For 2 decades, physicists have strived to miniaturize particle accelerators—the huge machines that serve as atom smashers and x-ray sources. That effort just took a big step, as physicists in China used a small “plasma wakefield accelerator” to power a type of laser called a free-electron laser (FEL). The 12-meter-long FEL isn’t nearly as good as its kilometers-long predecessors. Still, other researchers say the experiment marks a major advance in miniaccelerators.

Experiment demonstrates improvement in particle beams from plasma-based accelerators.

Roads that can charge electric cars or buses while you drive aren’t a new concept, but so far the technology has been relatively expensive and inefficient. However, Indiana’s Department of Transport (INDOT) has announced that it’s testing a new type of cement with embedded magnetized particles that could one day provide efficient, high-speed charging at “standard roadbuilding costs,” Autoblog has reported.

With funding from the National Science Foundation (NSF), INDOT has teamed with Purdue University and German company Magment on the project. They’ll carry out the research in three phases, first testing if the magnetized cement (called “magment,” naturally) will work in the lab, then trying it out on a quarter-mile section of road.

In a brochure, Magment said its product delivers “record-breaking wireless transmission efficiency [at] up to 95 percent,” adding that it can be built at “standard road-building installation costs” and that it’s “robust and vandalism-proof.” The company also notes that slabs with the embedded ferrite particles could be built locally, presumably under license.

Hemispherical array of ultrasound transducers lifts objects off reflective surfaces.

Researchers from Tokyo Metropolitan University have developed a new technology which allows non-contact manipulation of small objects using sound waves. They used a hemispherical array of ultrasound transducers to generate a 3D acoustic fields which stably trapped and lifted a small polystyrene ball from a reflective surface. Although their technique employs a method similar to laser trapping in biology, adaptable to a wider range of particle sizes and materials.

Continue reading “Acoustic Tweezers Can Pick Objects Up With Sound Waves – Without Any Physical Contact” »

Project offers new step toward study of emergence, ‘materials by design,’ and future nanomagnets.

Using a D-Wave quantum-annealing computer as a testbed, scientists at Los Alamos National Laboratory have shown that it is possible to isolate so-called emergent magnetic monopoles, a class of quasiparticles, creating a new approach to developing “materials by design.”

“We wanted to study emergent magnetic monopoles by exploiting the collective dynamics of qubits,” said Cristiano Nisoli, a lead Los Alamos author of the study. “Magnetic monopoles, as elementary particles with only one magnetic pole, have been hypothesized by many, and famously by Dirac, but have proved elusive so far.”