A method is investigated to manipulate the annihilation dynamics of a dense gas of positronium atoms employing superradiance and subradiance regimes of the cooperative spontaneous emission of the system. The corresponding annihilation dynamics is explored in two setups with regard to its fundamental novel properties and controlled by the gas density and by the intensity of a driving strong resonant laser field. In particular, the method allows us to increase the annihilation lifetime of an ensemble of positronium atoms by trapping the atoms in the excited state via collective radiative effects in the resonant laser field. In the second setup, the effect is enhanced by employing a cavity field. The maximum lifetime increase is by a factor of about 200 for para-positronium and by a factor of about 100 for ortho-positronium.
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http://dx.doi.org/10.1103/PhysRevLett.108.243401 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Physics and Astronomy, University of California, Irvine, CA 92697.
Understanding topological defects-controlled structural degradation of layered oxides-a key cathode material for high-performance lithium-ion batteries-plays a critical role in developing next-generation cathode materials. Here, by constructing a nanobattery in an electron microscope enabling atomic-scale monitoring of electrochemcial reactions, we captured the electrochemically driven atomistic dynamics and evolution of dislocations-a most important topological defect in material. We deciphered how dislocations nucleate, move, and annihilate within layered cathodes at the atomic scale.
View Article and Find Full Text PDFSoft Matter
January 2025
Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China.
Traveling waves are universal in excitable systems; yet, the microscopic dynamics of wave propagation is inaccessible in conventional excitable systems. Here, we show that active colloids of Quincke rollers driven by a periodic electric field can form condensed excitable phases. Distinct from existing excitable media, condensed excitable colloids can be tuned reversibly between active liquids and active crystals in which two distinct waves can be excited, respectively.
View Article and Find Full Text PDFInt J Cosmet Sci
January 2025
Makeup Products Research, Kao Corporation, Odawara, Japan.
Objective: Currently, nasolabial folds are mainly removed by invasive procedures, resulting in long-lasting changes, as non-surgical user-implementable alternatives are scarce and inefficient. For example, the use of coating films for this purpose has thus far faced substantial difficulties because such films should combine the antithetical properties of shrinkability and flexibility. Herein, we challenge this status quo by identifying a polymer that simultaneously exhibits shrinkability and flexibility and using this polymer to develop a cosmetic formulation for immediate and non-invasive nasolabial fold removal.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305.
A central paradigm of nonequilibrium physics concerns the dynamics of heterogeneity and disorder, impacting processes ranging from the behavior of glasses to the emergent functionality of active matter. Understanding these complex mesoscopic systems requires probing the microscopic trajectories associated with irreversible processes, the role of fluctuations and entropy growth, and the timescales on which nonequilibrium responses are ultimately maintained. Approaches that illuminate these processes in model systems may enable a more general understanding of other heterogeneous nonequilibrium phenomena, and potentially define ultimate speed and energy cost limits for information processing technologies.
View Article and Find Full Text PDFRSC Adv
January 2025
The Second Department, Xi' an Modern Chemistry Research Institute Xi'an 710065 China
To fully understand the variation in performance of cyclotrimethylenetrinitramine (RDX) crystals under strong magnetic field exposure, the strong magnetic loading of RDX was conducted in both stable and alternating magnetic fields. The morphological changes of RDX crystals exposed to magnetic fields were studied under a scanning electron microscope. Then, the lattice changes of RDX exposed to magnetic fields were analyzed through X-ray diffraction and Raman spectroscopy.
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