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Category: particle physics – Page 612

University of Oregon physicists have combined light and sound to control electron states in an atom-like system, providing a new tool in efforts to move toward quantum-computing systems.

The work was done on diamond topped with a layer of zinc oxide containing electrical conductors and performed at a temperature of 8 degrees Kelvin (−445.27 Fahrenheit, −265.15 Celsius) — just above absolute zero.

Using sound waves known as surface acoustic waves to change electron states could foster data transfer between quantum bits, the researcher said. The interaction of qubits, as is the case with binary bits in current computing, is seen as vital in building advanced systems.

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The theoretical results of a piece of international research published in Nature, whose first author is Ion Errea, a researcher at the UPV/EHU and DIPC, suggest that the quantum nature of hydrogen (in other words, the possibility of it behaving like a particle or a wave) considerably affects the structural properties of hydrogen-rich compounds (potential room-temperature superconducting substances). This is in fact the case of the superconductor hydrogen sulphide: a stinking compound that smells of rotten eggs, which when subjected to pressures a million times higher than atmospheric pressure, behaves like a superconductor at the highest temperature ever identified. This new advance in understanding the physics of high-temperature superconductivity could help to drive forward progress in the search for room-temperature superconductors, which could be used in levitating trains or next-generation supercomputers, for example.

Superconductors are materials that carry electrical current with zero electrical resistance. Conventional or low-temperature ones behave that way only when the substance is cooled down to temperatures close to absolute zero (−273 °C o 0 degrees Kelvin). Last year, however, German researchers identified the high-temperature superconducting properties of hydrogen sulphide which makes it the superconductor at the highest temperature ever discovered: −70 °C or 203 K.

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Nice read that ties Quantum properties such as tunneling to everything around us including our own blood supply in our bodies.

Objects of the quantum world are of a concealed and cold-blooded nature: they usually behave in a quantum manner only when they are significantly cooled and isolated from the environment. Experiments carried out by chemists and physicists from Warsaw have destroyed this simple picture. It turns out that not only does one of the most interesting quantum effects occur at room temperature and higher, but it plays a dominant role in the course of chemical reactions in solutions!

We generally derive our experimental knowledge of quantum phenomena from experiments carried out using sophisticated equipment under exotic conditions: at extremely low temperatures and in a vacuum, isolating quantum objects from the disturbing influence of the environment. Scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw, led by Prof. Jacek Waluk and Prof. Czeslaw Radzewicz’s group from the Faculty of Physics, University of Warsaw (FUW), have just shown that one of the most spectacular quantum phenomena — that of tunneling — takes place even at temperatures above the boiling point of water. However, what is particularly surprising is the fact that the observed effect applies to hydrogen nuclei, which tunnel in particles floating in solution. The results of measurements leave no doubt: in the studied system, in conditions typical for our environment, tunneling turns out to be the main factor responsible for the chemical reaction!

“For some time chemists have been getting used to the idea that electrons in molecules can tunnel. We have shown that in the molecule it is also possible for protons, that is, nuclei of hydrogen atoms, to tunnel. So we have proof that a basic chemical reaction can occur as a result of tunneling, and in addition in solution and at room temperature or higher,” explains Prof. Waluk.

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HUGE deal for wearables and biomed technologies.

Researchers from the University of Illinois at Urbana-Champaign have demonstrated a new approach to modifying the light absorption and stretchability of atomically thin two-dimensional (2D) materials by surface topographic engineering using only mechanical strain. The highly flexible system has future potential for wearable technology and integrated biomedical optical sensing technology when combined with flexible light-emitting diodes.

“Increasing graphene’s low light absorption in visible range is an important prerequisite for its broad potential applications in photonics and sensing,” explained SungWoo Nam, an assistant professor of mechanical science and engineering at Illinois. “This is the very first stretchable photodetector based exclusively on graphene with strain-tunable photoresponsivity and wavelength selectivity.”

Graphene—an atomically thin layer of hexagonally bonded carbon atoms—has been extensively investigated in advanced photodetectors for its broadband absorption, high carrier mobility, and mechanical flexibility. Due to graphene’s low optical absorptivity, graphene photodetector research so far has focused on hybrid systems to increase photoabsorption. However, such hybrid systems require a complicated integration process, and lead to reduced carrier mobility due to the heterogeneous interfaces.

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A strange new property of light, which correlates the spin of a light wave’s electric field with its momentum, could usher in a new age in photonics.

A new discovery links the spin and momentum of light waves, and could mean a major advance in the development of new photonic and spintronic devices.

Scientists from Purdue University have discovered a property of light waves called “spin-momentum locking,” which means that a rotating electric field accompanying light moves in a certain direction according to the photons’ momentum. In other words, light waves spinning counterclockwise move only “forward,” those spinning clockwise move only “backward.”

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Researchers with the University of Cambridge say they have the first real evidence of a new state of matter, some 40 years after it was first theorized.

Known as “quantum spin liquid,” the matter states causes normally unbreakable electrons to fracture into pieces, called “Majorana fermions.” These fermions are an important discovery: Physicists believe the material is crucial to further develop quantum computing. Computers employing Majorana fermions would be able to carry out calculations beyond the scope of modern computers quickly, they say.

Quantum spin liquid explains some of the odd behaviors inside magnetic materials. In these materials, the electrons should behave like small bar magnets, all aligning towards magnetic north when a material is cooled. But not all magnetic materials do this — if the material contains quantum spin liquid, the electrons don’t all line up and become entangled.

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Researchers have just discovered evidence of a mysterious new state of matter in a real material. The state is known as ‘quantum spin liquid’ and it causes electrons — one of the fundamental, indivisible building blocks of matter — to break down into smaller quasiparticles.

Scientists had first predicted the existence of this state of matter in certain magnetic materials 40 years ago, but despite multiple hints of its existence, they’ve never been able to detect evidence of it in nature. So it’s pretty exciting that they’ve now caught a glimpse of quantum spin liquid, and the bizarre fermions that accompany it, in a two-dimensional, graphene-like material.

“This is a new quantum state of matter, which has been predicted but hasn’t been seen before,” said one of the researchers, Johannes Knolle, from the University of Cambridge in the UK.

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The main benefit of an interstellar mission is to carry out in-situ measurements within a target star system. To allow for extended in-situ measurements, the spacecraft needs to be decelerated. One of the currently most promising technologies for deceleration is the magnetic sail which uses the deflection of interstellar matter via a magnetic field to decelerate the spacecraft. However, while the magnetic sail is very efficient at high velocities, its performance decreases with lower speeds. This leads to deceleration durations of several decades depending on the spacecraft mass. Within the context of Project Dragonfly, initiated by the Initiative of Interstellar Studies (i4is), this paper proposes a novel concept for decelerating a spacecraft on an interstellar mission by combining a magnetic sail with an electric sail. Combining the sails compensates for each technologys shortcomings: A magnetic sail is more effective at higher velocities than the electric sail and vice versa. It is demonstrated that using both sails sequentially outperforms using only the magnetic or electric sail for various mission scenarios and velocity ranges, at a constant total spacecraft mass. For example, for decelerating from 5% c, to interplanetary velocities, a spacecraft with both sails needs about 29 years, whereas the electric sail alone would take 35 years and the magnetic sail about 40 years with a total spacecraft mass of 8250 kg. Furthermore, it is assessed how the combined deceleration system affects the optimal overall mission architecture for different spacecraft masses and cruising speeds. Future work would investigate how operating both systems in parallel instead of sequentially would affect its performance. Moreover, uncertainties in the density of interstellar matter and sail properties need to be explored.

The Msail (Magnetic Sail) consists of a superconducting coil and support tethers which connect it to the spacecraft and transfer the forces onto the main structure. The current through the coil produces a magnetic field. When the spacecraft has a non-zero velocity, the stationary ions of the interstellar medium are moving towards the sail in its own reference frame. The interaction of ions with the magnetosphere of the coil leads to a momentum exchange and a force on the sail, along the direction of the incoming charged particles.

According to Zubrin, the current densities of superconductors can reach up to jmax = 2 · 1010A/m2 and this is the value used in the analysis. For the material of the sail, the density of common superconductors like copper oxide (CuO) and YBCO was used, with ρMsail = 6000 kg/m3.

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Game theory is a branch of mathematics that looks at how groups solve complex problems. The Schrödinger equation is the foundational equation of quantum mechanics — the area of physics focused on the smallest particles in the Universe. There’s no reason to expect one to have anything to do with the other.

But according to a team of French physicists, it’s possible to translate a huge number of problems in game theory into the language of quantum mechanics. In a new paper, they show that electrons and fish follow the exact same mathematics.

Schrödinger is famous in popular culture for his weird cat, but he’s famous to physicists for being the first to write down an equation that fully describes the weird things that happen when you try to do experiments on the fundamental constituents of matter. He realised that you can’t describe electrons or atoms or any of the other smallest pieces of the Universe as billiard balls that will be exactly where you expect them to be exactly when you expect them to be there.

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