The early history of laser cooling is a tale of three Nobel prizes and plenty of hard work, as Chad Orzel reveals.
Category: particle physics – Page 197
Perovskite-based light emitting diodes (LEDs) could be the key to developing internet bandwidths orders of magnitude faster than what is now available, while also keeping energy consumption and cost down, researchers have claimed. Other potential applications lie in laser technology.
Perovskite is a natural mineral first identified in Russia’s Ural Mountains in 1,839 and composed primarily of calcium, titanium, and oxygen – all in the 10 most common elements in the Earth’s crust. The mineral gave its name to a class of materials based on the same elements but doped with small quantities of others. For almost the first two centuries after their discovery, these perovskites were largely a curiosity of interest only to chemists.
More recently, however, the ability of perovskites to display different electrical properties depending on the atoms with which they are doped has turned them into a wonder material. Perovskites now represent one of the most efficient ways to trap energy from sunlight and are continuing to improve at unprecedented rates. Moreover, perovskites have the potential to be manufactured far more cheaply than traditional silicon-based solar cells, while a layer of perovskite over a silicon base could capture more light than either on their own.
The Rydberg state is prevalent across various physical mediums such as atoms, molecules, and solid materials. Rydberg excitons, which are highly energized, Coulomb-bound electron-hole pair states, were initially identified in the 1950s within the semiconductor material, Cu2O.
In a study published in Science, Dr. Xu Yang and his colleagues from the Institute of Physics (IOP) of the Chinese Academy of Sciences (CAS), in collaboration with researchers led by Dr. Yuan Shengjun of Wuhan University, have reported observing Rydberg moiré excitons, which are moiré-trapped Rydberg excitons in the monolayer semiconductor WSe2 adjacent to small-angle twisted bilayer graphene.
Graphene is an allotrope of carbon in the form of a single layer of atoms in a two-dimensional hexagonal lattice in which one atom forms each vertex. It is the basic structural element of other allotropes of carbon, including graphite, charcoal, carbon nanotubes, and fullerenes. In proportion to its thickness, it is about 100 times stronger than the strongest steel.
A long-standing challenge in the field of quantum physics is the efficient synchronization of individual and independently generated photons (i.e., light particles). Realizing this would have crucial implications for quantum information processing that relies on interactions between multiple photons.
Researchers at Weizmann Institute of Science recently demonstrated the synchronization of single, independently generated photons using an atomic quantum memory operating at room-temperature. Their paper, published in Physical Review Letters, could open new avenues for the study of multi-photon states and their use in quantum information processing.
“The project idea came about several years ago, when our group and the group of Ian Walmsley demonstrated an atomic quantum memory with an inverted atomic-level scheme compared to the typical memories—the ladder memory, named fast ladder memory (FLAME),” Omri Davidson, one of the researchers who carried out the study, told Phys.org. “These memories are fast and noise-free, and therefore they are useful for synchronization of single photons.”
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An international team of scientists has succeeded in experimentally confirming a characteristic of topological materials.
Scientists from around the globe have experimentally confirmed a unique characteristic of topological materials. Using ‘3D glasses’-like technology and particle accelerators, they successfully visualized the relationship between an electron’s topology and its quantum mechanical properties, marking a significant step forward in understanding these future-focused materials.
Topological quantum materials are seen as a beacon of hope for energy-saving electronics and the high-tech of the future. A defining feature of these materials is their ability to conduct spin-polarized electrons on their surface, while remaining non-conductive inside. To put this into perspective: In spin-polarized electrons, the intrinsic angular momentum, i.e. the direction of rotation of the particles (spin), is not purely randomly aligned.
A laser for vibrational energy, rather than for light, operating in the quantum regime could teach researchers about the interplay between spin, vibration, and dissipation in quantum mechanics.
Phonon lasers replace the light excitations (photons) that are used in a standard laser with vibrational excitations of matter (phonons). Researchers have now coaxed two ions into forming a phonon laser containing fewer than 10 phonons, placing it firmly in the quantum regime [1], whereas previous phonon lasers had at least 10,000 phonons. The researchers plan to use this quantum phonon laser as a tool to investigate the role of dissipation in the behavior of quantum systems.
Dissipation—energy leaking into or out of a system in the form of heat—is often seen as a nuisance in physics, for example, when it takes the form of air resistance and reduces the fuel efficiency of a car or an airplane. But quantum systems also exhibit dissipation, and its effects in the quantum realm are not fully understood. Jonathan Home of the Swiss Federal Institute of Technology (ETH) in Zurich and his colleagues wanted to investigate how two separate sources of dissipation can interact to affect the behavior of a quantum system. “A laser is the simplest quantum system we could think of” that allows such experiments, Home says.
A Pair of New Tetraquarks
Posted in particle physics
CERN’s Large Hadron Collider has detected the signals of two new four-quark states that are unusual because of their charges and their quark compositions.
Using the full capabilities of the Quantinuum H1-1 quantum computer, researchers from the Department of Energy’s Oak Ridge National Laboratory not only demonstrated best practices for scientific computing on current quantum systems but also produced an intriguing scientific result.
By modeling singlet fission —in which absorption of a single photon of light by a molecule produces two excited states —the team confirmed that the linear H4 molecule’s energetic levels match the fission process’s requirements. The linear H4 molecule is, simply, a molecule made of four hydrogen atoms arranged in a linear fashion.
A molecule’s energetic levels are the energies of each quantum state involved in a phenomenon, such as singlet fission, and how they relate and compare with one another. The fact that the linear molecule’s energetic levels are conducive to singlet fission could prove to be useful knowledge in the overall effort to develop more efficient solar panels.