The long-sought finding challenges scientists’ understanding of the strong nuclear force, and the AI that can beat human champions at drone racing.
For the first time, physicists from Finland and the United States have observed a special kind of magnetic monopole called an “Alice Ring.”
A team of researchers from the United States and Finland have observed enigmatic “Alice Rings” in super cold gas for the first time. A strange kind of circular magnetic monopoles, “Alice Rings” are a kind of quantum phenomenon that has, until now, only existed in theory. Various forces and particles can arise from the quantum machinery, theoretically including monopoles.
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A new symmetry-based classification could help researchers describe open, many-body quantum systems that display quantum chaos.
The quest for understanding quantum systems of many particles—and the exotic phenomena they display—fascinates theorists and experimentalists alike, but it’s one with many hurdles. The number of the system’s quantum states increases exponentially with size; these states are hard to prepare, probe, and characterize in experiments, and interactions with the environment “open” the system, further increasing the number of states to consider. As a result, open, many-body quantum systems remain a frontier of exploration in physics, for which researchers haven’t developed a systematic theoretical framework. A new study by Kohei Kawabata of Princeton University and colleagues has taken an important step toward developing such a general framework by offering a complete classification of these systems based on symmetry principles [1] (Fig. 1).
The observation of elusive, exotic particles is the key objective of countless studies, as it could open new avenues for research, while also improving present knowledge of the matter contained in the universe and its underlying physics. The quark model, a theoretical model introduced in 1964, predicted the existence of elementary subatomic particles known as quarks in their different configurations.
Quarks and antiquarks (the anti-matter equivalent of quarks) are predicted to be constituents of various subatomic particles. These include “conventional” particles, such as mesons and baryons, as well as more complex particles made up of four or five quarks (i.e., tetraquarks and pentaquarks, respectively).
The Large Hadron Collider beauty (LHCb) experiment, a research effort involving a large group of researchers at different institutes worldwide, has been trying to observe some of these fascinating particles for over a decade, using data collected at CERN’s LHC particle collider in Switzerland. In a recent paper published in Physical Review Letters, they reported the very first observation of a doubly charged tetraquark and its neutral partner.
The mysterious phenomenon that Einstein once described as “spooky action at a distance” was seen as a wavefunction between two entangled photons.
Quantum physics, the realm of science that describes the Universe at the smallest scales, is known for its counter-intuitive phenomena that seem to defy every law of physics on an everyday scale.
Arguably none of the aspects of quantum physics are as surprising or as troubling as entanglement, the idea that two particles can be connected in such a way that a change to one is instantly reflected in the other, even if the two particles are at opposite sides of the Universe. It’s the word “instantly” that troubled Albert Einstein enough to describe entanglement as “spooky action at a distance”.
A team from the University of Chicago has announced the first evidence for “quantum superchemistry” – a phenomenon where particles in the same quantum state undergo collective accelerated reactions. The effect had been predicted, but never observed in the laboratory.
The findings, published July 24 in Nature Physics, open the door to a new field. Scientists are intensely interested in what are known as “quantum-enhanced” chemical reactions, which could have applications in quantum chemistry, quantum computing, and other technologies, as well as in better understanding the laws of the universe.
Breakthrough could point way to fundamental insights, new technology.
When two sheets of graphene are placed on top of each other and slightly twisted, their atoms form a moiré pattern, or superlattice. At the so-called “magic” twist angle of 1.08°, something unusual happens: the weak van der Waals (vdW) coupling between atoms in adjacent layers modifies the atoms’ electronic states and transforms the material from a semimetal to a superconductor. The study of such twist-related electronic effects is known as “twistronics”, and it also includes phenomena such as correlated insulator states that appear at different degrees of misalignment.
Because the moiré pattern that underlies twistronics appears only at the interface between two thin sheets, it was assumed that twistronic effects could only occur in structures containing just a few layers. Although it is possible to produce a moiré pattern at a two-dimensional interface within a three-dimensional structure, it was thought that this pattern would not substantially modify the properties of the bulk material. After all, the 2D moiré region would only comprise a small fraction of the total 3D crystal volume.
New work by two research groups – one at the University of Washington in the US and Osaka University in Japan, the other at the University of Manchester in the UK – shows that this picture is not always correct. In fact, rotating a single layer of a 2D material by a small twist angle within a three-dimensional graphite film can cause the properties of the moiré interface to become inextricably mixed with those of the graphite. The result is a new class of hybrid 2D-3D moiré materials that substantially alters our understanding of how twistronics works.
67 years after its theoretical prediction by David Pines, the elusive “demon” particle, a massless and neutral entity in solids, has been detected in strontium ruthenate, underscoring the value of innovative research approaches.
In 1956, theoretical physicist David Pines predicted that electrons in a solid can do something strange. Although electrons typically have a mass and an electric charge, Pines asserted that they could combine to create a composite particle that is massless, neutral, and doesn’t interact with light. He named this theoretical particle a “demon.” Since then, it has been theorized to play an important role in the behaviors of a wide variety of metals. Unfortunately, the same properties that make it interesting have allowed it to elude detection since its prediction.
Fast forward 67 years, and a research team led by Peter Abbamonte, a professor of physics at the University of Illinois Urbana-Champaign (UIUC), has finally found Pines’ elusive demon. As the researchers report in the journal Nature, they used a nonstandard experimental technique that directly excites a material’s electronic modes, allowing them to see the demon’s signature in the metal strontium ruthenate.
A newly observed isotope of oxygen is defying all our expectations for how it should behave.
It’s oxygen-28, with the highest number of neutrons ever seen in the nucleus of an oxygen atom. Yet, while scientists believe it should be stable, it decays rapidly – calling into question what we thought we knew about “magic” numbers of particles in the nucleus of an atom.
The nucleus of an atom contains subatomic particles called nucleons, consisting of protons and neutrons.
Metrological institutions around the world administer our time using atomic clocks based on the natural oscillations of atoms. These clocks, pivotal for applications like satellite navigation or data transfer, have recently been improved by using ever higher oscillation frequencies in optical atomic clocks.
Now, scientists at the University of Innsbruck and the Institute of Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences led by Christian Roos show how a particular way of creating entanglement can be used to further improve the accuracy of measurements integral to an optical atomic clock’s function. Their results have been published in the journal Nature.
Observations of quantum systems are always subject to a certain statistical uncertainty. “This is due to the nature of the quantum world,” explains Johannes Franke from Christian Roos’ team. “Entanglement can help us reduce these errors.”
