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A feasibility study of the time reversal violation test based on polarization of annihilation photons from the decay of ortho-Positronium with the J-PET detector
摘要： The Jagiellonian Positron Emission Tomograph (J-PET) is a novel device being developed at Jagiellonian University in Krakow, Poland based on organic scintillators. J-PET is an axially symmetric and high acceptance scanner that can be used as a multi-purpose detector system. It is well suited to pursue tests of discrete symmetries in decays of positronium in addition to medical imaging. J-PET enables the measurement of both momenta and the polarization vectors of annihilation photons. The latter is a unique feature of the J-PET detector which allows the study of time reversal symmetry violation operator which can be constructed solely from the annihilation photons momenta before and after the scattering in the detector.
关键词： Time reversal symmetry,Momenta,Polarization,Annihilation photons,J-PET detector,Discrete symmetries,Ortho-positronium
更新于2025-09-23 15:23:52
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Broadband Nonreciprocity Enabled by Strong Coupling of Magnons and Microwave Photons
摘要： Nonreciprocity of signal transmission enhances the capacity of communication channels and protects the transmission quality against possible signal instabilities, thus becoming an important component for ensuring coherent information processing. However, nonreciprocal transmission requires breaking time-reversal symmetry (TRS), which poses challenges of both practical and fundamental character that hinder progress. Here we report an alternative scheme for achieving broadband nonreciprocity using a specially engineered hybrid microwave cavity. The TRS breaking is realized via strong coherent coupling between a selected chiral mode in the microwave cavity and a single collective spin excitation (magnon) in a ferromagnetic yttrium iron garnet sphere. The nonreciprocity in transmission is observed to span nearly a 0.5-GHz frequency band, which outperforms by two orders of magnitude the previously achieved bandwidths. Our findings suggest a promising direction for robust coherent information processing in a broad range of systems in both the classical and the quantum regime.
关键词： Broadband nonreciprocity,Time-reversal symmetry breaking,Microwave cavity,Magnon-photon coupling,Nonreciprocity
更新于2025-09-19 17:13:59
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Fabry-Perot interferometry in Weyl semi-metals
摘要： We show that the electrical transport across a minimal model for a time-reversal symmetry(TRS) breaking Weyl semi-metal (WSM) involving two Weyl nodes can be interpreted as an interferometer in momentum space. The interference phase depends on the distance between the Weyl nodes ( (cid:126)δk) and is anisotropic. It is further shown that a minimal inversion symmetry broken model for a WSM with four Weyl nodes effectively mimics a situation corresponding to having two copies of the interferometer due to the presence of an orbital pseudo-spin domain wall in momentum space. We point out that the value of the δk and consequently the interference phase can be tuned by driving the WSMs resulting in oscillations in the two terminal conductance measured in the direction of splitting of the Weyl nodes.
关键词： Weyl semi-metals,Fabry-Perot interferometry,inversion symmetry breaking,orbital pseudo-spin,time-reversal symmetry breaking
更新于2025-09-10 09:29:36
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SU(3) topological insulators in the honeycomb lattice
摘要： We investigate realizations of topological insulators with spin-1 bosons loaded in a honeycomb optical lattice and subjected to a SU(3) spin-orbit coupling—a situation which can be realized experimentally using cold atomic gases. In this paper, we focus on the topological properties of the single-particle band structure, namely, Chern numbers (lattice with periodic boundary conditions) and edge states (lattice with strip geometry) and their connection to time-reversal symmetry and the sublattice symmetry. While SU(2) spin-orbit couplings always lead to time-reversal symmetric tight-binding models, and thereby to topologically trivial band structures, suitable SU(3) spin-orbit couplings can break time-reversal symmetry and lead to topologically nontrivial bulk band structures and to edge states in the strip geometry. In addition, we show that one can trigger a series of topological transitions (i.e., integer changes of the Chern numbers) that are speci?c to the geometry of the honeycomb lattice by varying a single parameter in the Hamiltonian.
关键词： sublattice symmetry,SU(3) spin-orbit coupling,honeycomb optical lattice,spin-1 bosons,time-reversal symmetry,edge states,topological insulators,Chern numbers
更新于2025-09-09 09:28:46