Physicists finally know where at least some of these high-energy particles come from, which helps make the neutrinos useful for exploring fundamental physics.
Scientists have developed a multifunctional metalens capable of structuring quantum emissions from single photon.
A photon is a particle of light. It is the basic unit of light and other electromagnetic radiation, and is responsible for the electromagnetic force, one of the four fundamental forces of nature. Photons have no mass, but they do have energy and momentum. They travel at the speed of light in a vacuum, and can have different wavelengths, which correspond to different colors of light. Photons can also have different energies, which correspond to different frequencies of light.
There are several perfectly good reasons why water isn’t a popular medium for calligraphers to write in. Constantly shifting and swirling, it doesn’t take long for ink to diffuse and flow out of formation.
An ingenious ‘pen’ developed by the researchers from Johannes Gutenberg University Mainz (JGU) and the Technical University of Darmstadt in Germany, and Huazhong University of Science and Technology in China, could give artists a whole new medium to work with.
The new device is a tiny, 50 micron-wide bead made of a special material that exchanges ions in the liquid, creating zones of relatively low pH. Traces of particles suspended in the water are then drawn to the acidic solution. Drawing out that zone can create persistent, ‘written’ lines.
Almost a century ago, physicists Satyendra Nath Bose and Albert Einstein predicted a theoretical state of matter in which individual particles would, at extremely cold temperatures and low densities, condense into an indistinguishable whole. These so-called Bose-Einstein condensates (BECs) would offer a macroscopic view into the microscopic world of quantum mechanics. In 1995, theoretical BECs became an experimental reality, which garnered the physicists who created them a Nobel Prize. Labs around the world— and even in space —have been creating them ever since.
All of the BECs created so far to ask fundamental questions about quantum mechanics have been made from atoms. It has proven much harder to make molecules cold enough to approach a BEC state, which hover fractions of a degree above absolute zero, and to keep the molecules stable long enough to conduct experiments.
“For twenty years, there have been proposals about what you could do with stable ultracold molecules, but it has been tough on the experimental side because the lifetime of molecular samples has been short,” said Columbia physicist Sebastian Will, whose lab specializes in creating ultracold atoms and molecules.
Never let it be said that scientists don’t have an eye for the sublime.
Encoding and deciphering a Chinese symbol for duality and harmony into the quantum states of two entangled photons, physicists recently demonstrated the superior efficiency of a new analytical technique.
Researchers from the Sapienza University of Rome and the University of Ottawa in Canada used a method similar to a popular holographic technique to quickly and reliably measure information of a particle’s position.
Quantum technology’s future rests on the exploitation of fascinating quantum mechanics concepts—such as high-dimensional quantum states. Think of these states as basic ingredients of quantum information science and quantum tech. To manipulate these states, scientists have turned to light, specifically a property called orbital angular momentum (OAM), which deals with how light twists and turns in space. Here’s a catch: making super bright single photons with OAM in a deterministic fashion has been a tough nut to crack.
Now, enter quantum dots (QDs), tiny particles with big potential. A team of researchers from Sapienza University of Rome, Paris-Saclay University, and University of Naples Federico II combined the features of OAM with those of QDs to create a bridge between two cutting-edge technologies.
Their results are published in Advanced Photonics.
The first frequency-based limit on the neutrino’s mass sets the stage for next-generation experiments.
The Large Hadron Collider (LHC) is best known for the 2012 discovery of the Higgs boson, which was made by smashing together high-energy protons (see Collection: The History of Observations of the Higgs Boson). But protons are not the only particles accelerated by the collider, and some studies call for colliding much heavier objects. Now a team working on the LHC’s ALICE experiment has collided lead nuclei to study an exotic particle called a hypertriton [1]. The result could help researchers reduce errors in models of the structure of neutron stars.
A hypertriton is a tritium nucleus in which one neutron has been replaced with a lambda hyperon, a heavier particle with a quark configuration of up-down-strange rather than up-down-down. Researchers have long known the energy it takes to bind tritium’s proton and two neutrons. But it was unclear how that energy changed with the neutron–lambda hyperon switch.
The ALICE Collaboration turned to lead–lead collisions to answer this question because these collisions produce hypertritons in much greater numbers than proton–proton ones do. A hypertriton quickly decays into a helium-3 nucleus and a pion, with the decay time and the energy of the decay products depending on the binding energy between the lambda hyperon and the hypertriton core.
Active particles can form two-dimensional solids that are different from those formed by nonmotile particles, showing long-range crystalline order accompanied by giant spontaneous deformations.
If you compress a liquid slowly enough at low temperatures, it will freeze into an ordered solid: a crystal. Or at least that’s what we’re used to seeing in three dimensions. If you instead consider particles confined to a two-dimensional (2D) plane, the outcome is quite different. For equilibrium systems, a 2D solid stabilizes into a structure that lacks long-range order—it becomes less ordered further away from a central lattice site. The behavior of systems far from equilibrium, such as self-propelled particles, remains, however, an open question. In a numerical study of bacteria-like particles, Xia-qing Shi of Soochow University in China and his colleagues now show that active crystals follow a slightly different set of rules than their nonmotile counterparts [1]. Like 2D equilibrium crystals, 2D active systems stabilize into an ordered solid-like phase but with extremely large particle fluctuations around the configuration of a perfect crystal lattice.
Since the 1960s there has been plenty of evidence to support the existence of dark matter through astrophysical and cosmological observations, and at this point we’re very confident that it exists. The question remains, though: what is dark matter actually made of?
Throughout the decades there have been many candidates for dark matter, such as weakly interacting massive particles (WIMPs), neutrinos, and primordial black holes. Candidates like WIMPs were originally theorized because they have properties that address issues in other parts of physics. Another candidate that could answer some thorny physics questions is called the axion.
Axions were originally theorized as a solution to a particle physics question known as the Strong CP Problem, but physicists also realized that axions could be produced in a way that would satisfy requirements for them to be dark matter. These are the particles that the DMRadio experiments search for.
