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A quantum harmonic oscillator—a structure that can control the location and energy of quantum particles that could, in the future, be used to develop new technologies including OLEDs and miniature lasers—has been made at room temperature by researchers led by the University of St Andrews.

The research, conducted in collaboration with scientists at Nanyang Technological University in Singapore and published in Nature Communications recently, used an organic semiconductor to produce polaritons, which show quantum states even at room temperature.

Polaritons are quantum mixtures of light and matter that are made by combining excitations in a semiconductor material with photons, the fundamental particles that form light. To create polaritons, the researchers trapped light in a thin layer of an organic semiconductor (the kind of light-emitting material used in OLED smartphone displays) 100 times thinner than a single human hair, sandwiched between two highly reflective mirrors.

The meteorite and explosion-site quasicrystals were both uncovered by a team that includes Luca Bindi of the University of Florence, Italy, and Paul Steinhardt of Princeton University. In those previous cases, the materials were subjected to extremely high-pressure, high-temperature shock events—analysis of the meteorite sample revealed the temperature reached at least 1,200 °C and the pressure 5 GPa, while the New Mexico sample reached 1,500 °C and closer to 8 GPa. These transient, intense conditions contorted the materials’ atoms, forcing them to arrange into patterns unseen for usual laboratory conditions.

The explosion-site sample was found in a rock-like substance made of sand that had been fused together with copper wires from a measurement device that had been set up to monitor the atom-bomb test. As a trained geologist, Bindi was aware that similar substances—so-called fulgurites—are created when lightning strikes a beach or a sand dune. He wondered if lightning-fused samples might also contain quasicrystals, so he and the team set about collecting and analyzing the structures of as many fulgurites as they could lay their hands on.

Luck was on their side. In a fragment of a storm-created fulgurite from the Nebraskan Sand Hills—grass-stabilized sand dunes in northern Nebraska—the team found a micron-sized fragment of a quasicrystal with a previously unseen composition and pattern. Specifically, the newly discovered quasicrystal has a dodecagonal—12-fold symmetric—atomic structure. Such ordering is impossible in ordinary crystals, Bindi says, and is unusual even for quasicrystals (both the meteorite and explosion-site quasicrystals, as well as most lab-made ones, have fivefold symmetric patterns). “This was all more than [we] could have hoped for in such a long-shot search,” Steinhardt says.

Japan says it will release more than a million tonnes of water into the sea from the destroyed Fukushima nuclear power plant this year.

After treatment the levels of most radioactive particles meet the national standard, the operator said.

The International Atomic Energy Agency (IAEA) says the proposal is safe, but neighbouring countries have voiced concern.

Continue reading “Fukushima nuclear disaster: Japan to release radioactive water into sea this year” »

Researchers have developed a way to use laser light to pull a macroscopic object. Although microscopic optical tractor beams have been demonstrated before, this is one of the first times that laser pulling has been used on larger objects.

Light contains both energy and momentum that can be used for various types of optical manipulation such as levitation and rotation. Optical tweezers, for example, are commonly used scientific instruments that use laser light to hold and manipulate tiny objects such as atoms or cells. For the last ten years, scientists have been working on a new type of optical manipulation: using laser light to create an optical tractor beam that could pull objects.

Continue reading “Researchers create an optical tractor beam that pulls macroscopic objects” »

The early 20^th century saw the advent of quantum mechanics to describe the properties of small particles, such as electrons or atoms. Schrödinger’s equation in quantum mechanics can successfully predict the electronic structure of atoms or molecules. However, the “duality” of matter, referring to the dual “particle” and “wave” nature of electrons, remained a controversial issue. Physicists use a complex wavefunction to represent the wave nature of an electron.

“Complex” numbers are those that have both “real” and “imaginary” parts—the ratio of which is referred to as the “phase.” However, all directly measurable quantities must be “real”. This leads to the following challenge: when the electron hits a detector, the “complex” phase information of the wavefunction disappears, leaving only the square of the amplitude of the wavefunction (a “real” value) to be recorded. This means that electrons are detected only as particles, which makes it difficult to explain their dual properties in atoms.

The ensuing century witnessed a new, evolving era of physics, namely, attosecond physics. The attosecond is a very short time scale, a billionth of a billionth of a second. “Attosecond physics opens a way to measure the phase of electrons. Achieving attosecond time-resolution, electron dynamics can be observed while freezing molecular motion,” explains Professor Hiromichi Niikura from the Department of Applied Physics, Waseda University, Japan, who, along with Professor D. M. Villeneuve—a principal research scientist at the Joint Attosecond Science Laboratory, National Research Council, and adjunct professor at University of Ottawa—pioneered the field of attosecond physics.

Researchers have observed steric effects—the interactions of molecules depending on their spatial orientation (not just between their electrons involved in bonding)—in a chemical reaction involving non-polar molecules for the first time. The breakthrough opens the door to an entirely new way to control the products of chemical reactions.

A paper describing the research team’s findings was published in the journal Science on Jan. 12.

One of the central goals of chemistry is to develop new methods of controlling chemical reactions. For the most part, control of chemical reactions involves understanding of the interactions between the electrons of different atoms. These “electronic” effects govern many of the properties and behavior of chemicals and the changes they undergo during reactions.

Of course, all stars are hot compared with anything we’re used to here on Earth. But while the Sun’s surface chills at a steady 6,000 degrees Kelvin, these stars’ extreme temperatures range from 100,000 to 180,000 degrees.

These are “stars which are a little bit outside the canonical evolution,” Klaus Werner of the University of Tuebingen’s Kepler Centre for Astro and Particle Physics, a co-author of the paper, tells Inverse. “These stars are strange.”

Even among the ultra-hot white dwarfs known by the designation PG1159, the selection that cropped up in this survey lack the helium normally found in their atmosphere: instead, they’ve burned it all away, fusing it into a solar atmosphere of pure carbon and oxygen.

Silently churning away at the heart of every atom in the Universe is a swirling wind of particles that physics yearns to understand.

No probe, no microscope, and no X-ray machine can hope to make sense of the chaotic blur of quantum cogs whirring inside an atom, leaving physicists to theorize the best they can based on the debris of high-speed collisions inside particle colliders.

Researchers now have a new tool that is already providing them with a small glimpse into the protons and neutrons that form the nuclei of atoms, one based on the entanglement of particles produced as gold atoms brush past each other at speed.

The world of the very, very small is a wonderland of strangeness. Molecules, atoms, and their constituent particles did not readily reveal their secrets to the scientists that wrestled with the physics of atoms in the early 20th century. Drama, frustration, anger, puzzlement, and nervous breakdowns abounded, and it is hard for us now, a full century later, to understand what was at stake. What happened was a continuous process of worldview demolition. You might have to give up believing everything you thought to be true about something. In the case of the quantum physics pioneers, that meant changing their understanding about the rules that dictate how matter behaves.

In 1913, Bohr devised a model for the atom that looked somewhat like a solar system in miniature. Electrons moved around the atomic nucleus in circular orbits. Bohr added a few twists to his model — twists that gave them a set of weird and mysterious properties. The twists were necessary for Bohr’s model to have explanatory power — that is, for it to be able to describe the results of experimental measurements. For example, electrons’ orbits were fixed like railroad tracks around the nucleus. The electron could not be in between orbits, otherwise it could fall into the nucleus. Once it got to the lowest rung in the orbital ladder, an electron stayed there unless it jumped to a higher orbit.

Clarity about why this happened started to come with de Broglie’s idea that electrons can be seen both as particles and waves. This wave-particle duality of light and matter was startling, and Heisenberg’s uncertainty principle gave it precision. The more precisely you localize the particle, the less precisely you know how fast it moves. Heisenberg had his own theory of quantum mechanics, a complex device to compute the possible outcomes of experiments. It was beautiful but extremely hard to calculate things with.