Bloch oscillations are periodic oscillations of quantum particles in a repeating energy “landscape” (e.g., a crystal lattice) that are subjected to a constant force. These particle motions have been the focus of numerous physics studies, as they are intriguing quantum effects that are not predicted by classical mechanics theories.
Probing Bloch oscillations experimentally could thus yield new insight into the fundamental properties of quantum matter. So far, they have been primarily studied in individual particles or two-particle systems, as opposed to quantum many-body systems comprised of several particles.
Researchers at CNRS-ENS-PSL University and Sorbonne University report the observation of collective Bloch oscillations in a one-dimensional (1D) Bose gas, a quantum fluid comprised of bosons, which are particles that can occupy the same quantum state.
You probably learned in high school chemistry class that core electrons don’t participate in chemical bonding.
They’re thought to be too deep inside an atom and close to the nucleus to meaningfully interact with the electrons of other atoms, leaving the outer valence electrons to get all the chemical bonding glory in textbooks.
The actual science is more complicated, as some elements’ core electrons are theorized to activate when squeezed hard enough, like at the pressure levels found deep inside Earth.
Experiments at the Relativistic Heavy Ion Collider give the first hints of a critical point in the hot quark–gluon “soup” that is thought to have pervaded the infant Universe.
The strongest force of nature—the one holding nuclear matter together—is described by the theory of quantum chromodynamics (QCD). The fundamental particles of QCD are quarks and gluons, which are normally bound within composite particles called hadrons—the most well-known of which are protons and neutrons. Only at extreme temperatures around 1012 K (a million times hotter than the core of the Sun) can quarks and gluons become deconfined, leading to a new phase of matter called the quark–gluon plasma. At vanishing densities, the transition between confined hadrons and the quark–gluon plasma is known to be ill-defined—happening across a wide range of temperatures rather than at a specific temperature. But theory predicts that at large densities and moderately high temperatures, a critical point exists, where the “fuzziness” disappears and a clear distinction can be made between the gas-like hadrons and the liquid-like quark–gluon mix [1–3].
Determining the nature of dark matter, the invisible substance that makes up most of the mass in our universe, is one of the greatest puzzles in physics. New results from the world’s most sensitive dark matter detector, LUX-ZEPLIN (LZ), have narrowed down the possibilities for one of the leading dark matter candidates: weakly interacting massive particles (WIMPs).
Members of the STAR collaboration, a group of physicists collecting and analyzing data from particle collisions at the Relativistic Heavy Ion Collider (RHIC), have published a new high-precision analysis of data on the number of protons produced in gold-ion smashups over a range of energies.
The results, published in Physical Review Letters, suggest scientists have observed one part of a key signature of a “critical point.” That’s a unique point on the “map” of nuclear phases that marks a change in the way quarks and gluons, the building blocks of protons and neutrons, transition from one phase of matter to another.
Discovering the critical point has been a central goal of research at RHIC, a U.S. Department of Energy (DOE) Office of Science user facility for nuclear physics research at DOE’s Brookhaven National Laboratory. Like centuries-old efforts to map out the solid, liquid, and gaseous phases of substances like water, it’s considered essential for fully understanding and describing the quark-gluon plasma.
