Here’s what it takes to pause the perpetual motion of particles.
Category: particle physics – Page 223
A new phase of matter: Physicists achieve first demonstration of non-Abelian anyons in a quantum processor
Our physical, 3D world consists of just two types of particles: bosons, which include light and the famous Higgs boson; and fermions—the protons, neutrons, and electrons that comprise all the “stuff,” present company included.
Theoretical physicists like Ashvin Vishwanath, Harvard’s George Vasmer Leverett Professor of Physics, don’t like to limit themselves to just our world, though. In a 2D setting, for instance, all kinds of new particles and states of matter would become possible.
Vishwanath’s team used a powerful machine called a quantum processor to make, for the first time, a brand-new phase of matter called non-Abelian topological order. Previously recognized in theory only, the team demonstrated synthesis and control of exotic particles called non-Abelian anyons, which are neither bosons nor fermions, but something in between.
Harnessing the Power of Neutrality: Comparing Neutral-Atom Quantum Computing With Other Modalities
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.
‘Quantum gravity’ could help unite quantum mechanics with general relativity at last
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.”
Why string theory has been unfairly maligned
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.
Laser-Cooling Positronium
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.
