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Feb 23, 2024

Antimatter: Scientists freeze positronium atoms with lasers

Posted by in category: particle physics

Positronium has the potential to revolutionise physics but the elusive substance had been too hot to handle.

Feb 23, 2024

Harnessing the Power of Neutrality: Comparing Neutral-Atom Quantum Computing With Other Modalities

Posted by in categories: computing, particle physics, quantum physics

How Does The Neutral Atom Approach Compare

The neutral atom approach is a well-known and extensively investigated approach to quantum computing. The approach offers numerous advantages, especially in terms of scalability, expense, error mitigation, error correction, coherence, and simplicity.

Neutral atom quantum computing utilizes individual atoms, typically alkali atoms like rubidium or cesium, suspended and isolated in a vacuum and manipulated using precisely targeted laser beams. These atoms are not ionized, meaning they retain all their electrons and do not carry an electric charge, which distinguishes them from trapped ion approaches. The quantum states of these neutral atoms, such as their energy levels or the orientation of their spins, serve as the basis for qubits. By employing optical tweezers—focused laser beams that trap and hold the atoms in place—arrays of atoms can be arranged in customizable patterns, allowing for the encoding and manipulation of quantum information.

Feb 23, 2024

‘Quantum gravity’ could help unite quantum mechanics with general relativity at last

Posted by in categories: cosmology, particle physics, quantum physics

One of the primary reasons for this dilemma is that, while three of the universe’s four fundamental forces — electromagnetism, the strong nuclear force and the weak nuclear force — have quantum descriptions, there is no quantum theory of the fourth: Gravity.

Now, however, an international team has made headway in addressing this imbalance by successfully detecting a weak gravitational pull on a tiny particle using a new technique. The researchers believe this could be the first tentative step on a path that leads to a theory of “quantum gravity.”

“For a century, scientists have tried and failed to understand how gravity and quantum mechanics work together,” Tim Fuchs, team member and a scientist at the University of Southampton, said in a statement. “By understanding quantum gravity, we could solve some of the mysteries of our universe — like how it began, what happens inside black holes, or uniting all forces into one big theory.”

Feb 23, 2024

All-atom RNA structure determination from cryo-EM maps

Posted by in categories: mapping, particle physics, robotics/AI

RNA structures are built from cryogenic electron microscopy maps using deep learning and backbone tracing.

Feb 23, 2024

Why string theory has been unfairly maligned

Posted by in categories: particle physics, quantum physics

String theory is widely considered beyond empirical investigation. But we could conceivably test it thanks to ancient particles called moduli, which might appear in astronomical observations, says theorist Joseph Conlon.

By Thomas Lewton

Feb 23, 2024

Laser-Cooling Positronium

Posted by in category: particle physics

The goal of the AEgIS Collaboration at CERN in Switzerland is to measure the effect of Earth’s gravitational field on antimatter—specifically, antihydrogen atoms. Antihydrogen is produced using positronium—which consists of an electron and a positron bound together—and the colder the positronium, the faster the antihydrogen production rate. Accordingly, AEgIS researchers have spent the past four years trying to develop a way to cool positronium. Now, with their first demonstration of positronium laser cooling, they have succeeded [1].

Laser-cooling positronium is a much tougher undertaking than laser-cooling regular atoms. Positronium can only survive for 140 nanoseconds before annihilating, even in ultrahigh vacuum. Moreover, the relevant transition frequency for positronium cooling is in the deep ultraviolet, where laser technology remains relatively undeveloped.

The AEgIS Collaboration designed a custom laser system that uses the mineral alexandrite as the lasing medium. Alexandrite-based lasers emit at deep-ultraviolet wavelengths, but devices that meet the intensity and pulse-length requirements for positronium cooling are not commercially available. The researchers also had to overcome another major hurdle: to avoid the loss of positronium atoms during the cooling process, any external electric and magnetic fields had to be eliminated. As a result, the electrostatic equipment used for manipulating the positronium had to be capable of being switched off in a matter of nanoseconds.

Feb 23, 2024

Three’s Company for Bottom Quarks

Posted by in category: particle physics

Bottom quarks are increasingly more likely to exist in three-quark states rather than two-quark ones as the density of their environment increases.

Feb 23, 2024

Experiment paves the way for new set of antimatter studies by laser-cooling positronium

Posted by in categories: particle physics, space

AEgIS is one of several experiments at CERN’s Antimatter Factory producing and studying antihydrogen atoms with the goal of testing with high precision whether antimatter and matter fall to Earth in the same way.

In a paper published today in Physical Review Letters, the AEgIS collaboration reports an experimental feat that will not only help it achieve this goal but also pave the way for a whole new set of antimatter studies, including the prospect to produce a gamma-ray laser that would allow researchers to look inside the atomic nucleus and have applications beyond physics.

Continue reading “Experiment paves the way for new set of antimatter studies by laser-cooling positronium” »

Feb 23, 2024

“None of Us Expected This” — Scientists Have Discovered 2D Waveguides

Posted by in categories: nanotechnology, particle physics

The U.S. Naval Research Laboratory (NRL), working together with Kansas State University, has announced the discovery of slab waveguides made from the two-dimensional material hexagonal boron nitride. This milestone has been documented in the journal Advanced Materials.

Two-dimensional (2D) materials are a class of materials that can be reduced to the monolayer limit by mechanically peeling the layers apart. The weak interlayer attractions, or van der Waals attraction, allows the layers to be separated via the so-called “Scotch tape” method. The most famous 2D material, graphene, is a semimetallic material consisting of a single layer of carbon atoms. Recently, other 2D materials including semiconducting transition metal dichalcogenides (TMDs) and insulating hexagonal boron nitride (hBN) have also garnered attention. When reduced near the monolayer limit, 2D materials have unique nanoscale properties that are appealing for creating atomically thin electronic and optical devices.

Feb 23, 2024

Quantum Breakthrough in High-Temperature Superconductivity

Posted by in categories: particle physics, quantum physics

An international team of scientists has made a new discovery that may help to unlock the microscopic mystery of high-temperature superconductivity and address the world’s energy problems.

In a paper published in the journal Nature, Swinburne University of Technology’s Associate Professor Hui Hu collaborated with researchers at the University of Science and Technology of China (USTC) in a new experimental observation quantifying the pseudogap pairing in a strongly attractive interacting cloud of fermionic lithium atoms.

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