Lifeboat Foundation

Using a network of vibrating nano-strings controlled with light, researchers from AMOLF have made sound waves move in a specific irreversible direction and attenuated or amplified the waves in a controlled manner for the first time. This gives rise to a lasing effect for sound. To their surprise, they discovered new mechanisms, so-called “geometric phases,” with which they can manipulate and transmit sound in systems where that was thought to be impossible. “This opens the way to new types of (meta)materials with properties that we do not yet know from existing materials,” says group leader Ewold Verhagen who, together with shared first authors Javier del Pino and Jesse Slim, publishes the surprising results on June 2 in Nature.

The response of electrons and other charged particles to magnetic fields leads to many unique phenomena in materials. “For a long time, we have wanted to know whether an effect similar to a magnetic field on electrons could be achieved on sound, which has no charge,” says Verhagen. “The influence of a magnetic field on electrons has a wide impact: for example, an electron in a magnetic field cannot move along the same path in the opposite direction. This principle lies at the basis of various exotic phenomena at the nanometer scale, such as the quantum Hall effect and the functioning of topological insulators (materials that conduct current perfectly at their edges and not in their bulk). For many applications, it would be useful if we could achieve the same for vibrations and sound waves and therefore break the symmetry of their propagation, so it is not time-reversal symmetric anymore.”

Scientists have created the first “time-crystal” two-body system in an experiment that seems to bend the laws of physics.

It comes after the same team recently witnessed the first interaction of the new phase of matter.

Time crystals were long believed to be impossible because they are made from atoms in never-ending motion. The discovery, published in Nature Communications, shows that not only can time crystals be created, but they have potential to be turned into useful devices.

Teams from Helmholtz-Zentrum Berlin (HZB) and University College London (UCL) have visualized the water distribution in a fuel cell in three dimensions and in real time for the first time by evaluating neutron data from the Berlin Experimental Reactor shut down in 2019. The analysis opens new possibilities for more efficient and thus more cost-effective fuel cells.

“In a fuel cell, hydrogen and oxygen are combined to form water. This produces electrical energy,” explains Ralf Ziesche from the imaging group at HZB. “Probably the most important component inside the fuel cell is the membrane.” It is only about 20 micrometers thick (half as wide as a human hair) and connected with various functional layers to form a separation area about 600 micrometers wide inside the fuel cell.

“The membrane composite snatches the electrons from the hydrogen atoms. Only the hydrogen nuclei—the protons—can pass through the membrane.” The electrons, on the other hand, flow off via an electrical connection and are used as an electric current. Air is let in on the other side of the separating wall. The oxygen it contains reacts with the protons that come through the membrane and the electrons that flow back from the other side of the electric circuit. Pure water is produced.

Distinctive features of gravitational-wave signals from black hole mergers could reveal the existence of long-sought ultralight bosons.

X-ray analysis reveals lattice distortions are behind silver gallium telluride’s thermoelectric properties, a finding that could advance green technologies.

A model attributes the propagating bands that appear in a compressed porous medium to structural changes alone.

Physicists have just taken an amazing step towards quantum devices that sound like something out of science fiction.

For the first time, isolated groups of particles behaving like bizarre states of matter known as time crystals have been linked into a single, evolving system that could be incredibly useful in quantum computing.

Following the first observation of the interaction between two time crystals, detailed in a paper two years ago, this is the next step towards potentially harnessing time crystals for practical purposes, such as quantum information processing.

When it is free in cold space, a molecule will spontaneously cool down by slowing its rotation and losing rotational energy in quantum transitions. Physicists have shown that this rotational cooling process can be accelerated, slowed down and even inverted by the molecule’s collisions with surrounding particles.

Researchers at the Max-Planck Institute for Nuclear Physics in Germany and the Columbia Astrophysics Laboratory have recently carried out an experiment aimed at measuring the rate of quantum transitions caused by collisions between molecules and electrons. Their findings, published in Physical Review Letters, offer the first experimental evidence of this rate, which had previously only been theoretically estimated.

“When electrons and molecular ions are present in tenuous, ionized gases, the lowest quantum level populations of the molecules can be changed in a collision process,” Ábel Kálosi, one of the researchers who carried out the study, told Phys.org. “One example of this process is in interstellar clouds, where observations reveal molecules predominantly in their lowest quantum states. The attractive force between the negatively charged electrons and the positively charged molecular ions makes the process of electronic collisions particularly efficient.”

While volcanic eruptions and earthquakes serve as immediate reminders that Earth’s interior is anything but peaceful, there are also other, more elusive, dynamic processes taking place deep down below our feet. Using information from ESA’s Swarm satellite mission, scientists have discovered a completely new type of magnetic wave that sweeps across the outermost part of Earth’s outer core every seven years. This fascinating finding, presented today at ESA’s Living Planet Symposium, opens a new window into a world we can never see.

Earth’s magnetic field is like a huge bubble protecting us from the onslaught of cosmic radiation and charged particles carried by powerful winds that escape the Sun’s gravitational pull and stream across the Solar System. Without our magnetic field, life as we know it could not exist.

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The experiment will investigate the Unruh effect, which is produced by a mixture of quantum mechanics and special relativity.