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Category: particle physics – Page 384

Single molecules can work as reproducible transistors—at room temperature

A major goal in the field of molecular electronics, which aims to use single molecules as electronic components, is to make a device where a quantized, controllable flow of charge can be achieved at room temperature. A first step in this field is for researchers to demonstrate that single molecules can function as reproducible circuit elements such as transistors or diodes that can easily operate at room temperature.

A team led by Latha Venkataraman, professor of applied physics and chemistry at Columbia Engineering and Xavier Roy, assistant professor of chemistry (Arts & Sciences), published a study in Nature Nanotechnology that is the first to reproducibly demonstrate current blockade—the ability to switch a device from the insulating to the conducting state where charge is added and removed one electron at a time—using atomically precise molecular clusters at .

Bonnie Choi, a graduate student in the Roy group and co-lead author of the work, created a single cluster of geometrically ordered atoms with an inorganic core made of just 14 atoms—resulting in a diameter of about 0.5 nanometers—and positioned linkers that wired the core to two gold electrodes, much as a resistor is soldered to two metal electrodes to form a macroscopic electrical circuit (e.g. the filament in a light bulb).

Unusual superconductivity observed in twisted trilayer graphene

The ability to turn superconductivity off and on with a literal flip of a switch in so-called “magic-angle twisted graphene” has allowed engineers at Caltech to observe an unusual phenomenon that may shed new light on superconductivity in general.

The research, led by Stevan Nadj-Perge, assistant professor of applied physics and , was published in the journal Nature on June 15.

Magic-angle twisted graphene, first discovered in 2018, is made from two or three sheets of graphene (a form of carbon consisting of a single layer of atoms in a honeycomb-like lattice pattern) layered atop one another, with each sheet twisted at precisely 1.05 degrees in relation to the one below it. The resulting bilayer or trilayer has unusual electronic properties: for example, it can be made into an insulator or a superconductor depending on how many are added.

Physicists discover a ‘family’ of robust, superconducting graphene structures

Martin ChartrandListen to the sound, more like a musket than a 3D printed plastic gun.

When it comes to graphene, it appears that superconductivity runs in the family.

Graphene is a single-atom-thin material that can be exfoliated from the same graphite that is found in pencil lead. The ultrathin material is made entirely from carbon atoms that are arranged in a simple hexagonal pattern, similar to that of chicken wire. Since its isolation in 2004, has been found to embody numerous remarkable properties in its single-layer form.

In 2018, MIT researchers found that if two graphene layers are stacked at a very specific “magic” angle, the twisted bilayer structure could exhibit robust superconductivity, a widely sought material state in which an can flow through with zero energy loss. Recently, the same group found a similar superconductive state exists in twisted trilayer graphene—a structure made from three graphene layers stacked at a precise, new magic angle.

Record-setting quantum entanglement connects two atoms across 20 miles

Researchers in Germany have demonstrated quantum entanglement of two atoms separated by 33 km (20.5 miles) of fiber optics. This is a record distance for this kind of communication and marks a breakthrough towards a fast and secure quantum internet.

Quantum entanglement is the uncanny phenomenon where two particles can become so inextricably linked that examining one can tell you about the state of the other. Stranger still, changing something about one particle will instantly alter its partner, no matter how far apart they are. That leads to the unsettling implication that information is being “teleported” faster than the speed of light, an idea that was too much for even Einstein, who famously described it as “spooky action at a distance.”

Despite its apparent impossibility, quantum entanglement has been consistently demonstrated in experiments for decades, with scientists taking advantage of its bizarre nature to quickly transmit data over long distances. And in the new study, researchers from Ludwig-Maximilians-University Munich (LMU) and Saarland University have now broken a distance record for quantum entanglement between two atoms over fiber optics.

Cern physicists find evidence of three new ‘exotic’ particles

‘The more analyses we perform, the more kinds of exotic hadrons we find’

In the last two years, researchers have discovered a tetraquark made up of two charm quarks and two charm antiquarks, and two “open-charm” tetraquarks consisting of a charm antiquark, an up quark, a down quark and a strange antiquark.

“The more analyses we perform, the more kinds of exotic hadrons we find. We’re witnessing a period of discovery similar to the 1950s, when a ‘particle zoo’ of hadrons started being discovered and ultimately led to the quark model of conventional hadrons in the 1960s. We’re creating ‘particle zoo 2.0,” LHCb physics coordinator Niels Tuning said in a statement.

Last year, researchers also found the first-ever instance of a “double open-charm” tetraquark with two charm quarks and an up and a down antiquark.

Researchers achieve record entanglement of quantum memories

A network in which data transmission is perfectly secure against hacking? If physicists have their way, this will become reality one day with the help of the quantum mechanical phenomenon known as entanglement. For entangled particles, the rule is: If you measure the state of one of the particles, then you automatically know the state of the other. It makes no difference how far away the entangled particles are from each other. This is an ideal state of affairs for transmitting information over long distances in a way that renders eavesdropping impossible.

A team led by physicists Prof. Harald Weinfurter from LMU and Prof. Christoph Becher from Saarland University have now coupled two atomic over a 33-kilometer-long fiber optic connection. This is the longest distance so far that anyone has ever managed entanglement via a telecom fiber.

The quantum mechanical entanglement is mediated via photons emitted by the two quantum memories. A decisive step was the researchers’ shifting of the wavelength of the emitted light particles to a value that is used for conventional telecommunications. “By doing this, we were able to significantly reduce the loss of photons and create entangled quantum memories even over long distances of fiber optic cable,” says Weinfurter.

Good news, universe! Scientists are one step closer to finally understanding dark matter

Dark matter is made up of axions, elementary particles that are full of suspense.

About 85 percent of our universe is believed to be composed of dark matter, a hypothetical material that does not interact with light. So it neither reflects nor emits nor absorbs any light rays, and therefore, we can not see this unusual form of the matter directly. However, to understand and explain the nature of dark matter, scientists have created various models.

Surprisingly, a new study has ruled out one such popular explanation of the dark matter, called the axion-like particle (ALP) cogenesis model. The exclusion of ALP means that scientists will now have to consider fewer models while conducting dark matter research. This would increase both the speed and accuracy of their research works and bring us one step closer to understanding the most strange phenomenon of the universe. matter is made up of axons. Recently, scientists from the University of Australia decided to exclude a popular model (ALP cogenesis model) that is used to explain the nature of dark matter.

Why does inside of solar system not spin faster? Old mystery has possible new solution

The motion of a tiny number of charged particles may solve a longstanding mystery about thin gas disks rotating around young stars, according to a new study from Caltech.

These features, called , last tens of millions of years and are an early phase of solar system evolution. They contain a small fraction of the mass of the star around which they swirl; imagine a Saturn-like ring as big as the solar system. They are called accretion disks because the gas in these disks spirals slowly inward toward the star.

Scientists realized long ago that when this inward spiraling occurs, it should cause the radially inner part of the disk to spin faster, according to the law of the conservation of angular momentum. To understand conservation of angular momentum, think of spinning figure skaters: when their arms are outstretched, they spin slowly, but as they draw their arms in, they spin faster.

Scientists invent ‘quantum flute’ that can make particles of light move together

University of Chicago physicists have invented a “quantum flute” that, like the Pied Piper, can coerce particles of light to move together in a way that’s never been seen before.

Described in two studies published in Physical Review Letters and Nature Physics, the breakthrough could point the way towards realizing or new forms of error correction in quantum computers, and observing quantum phenomena that cannot be seen in nature.

Assoc. Prof. David Schuster’s lab works on —the quantum equivalent of a computer bit—which tap the strange properties of particles at the atomic and sub-atomic level to do things that are otherwise impossible. In this experiment, they were working with particles of light, known as photons, in the microwave spectrum.

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