A5102720032- Atomic and Molecular Physics
- Gyrotron and Vacuum Electronics Research
- Quantum many-body systems
- Muon and positron interactions and applications
- Physics of Superconductivity and Magnetism
- Neutrino Physics Research
- Advanced Condensed Matter Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Particle accelerators and beam dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum and electron transport phenomena
- Advanced Frequency and Time Standards
- Dark Matter and Cosmic Phenomena
- Topological Materials and Phenomena
- Nuclear physics research studies
- Magnetic properties of thin films
- Particle physics theoretical and experimental studies
- Algebraic structures and combinatorial models
- Quantum Chromodynamics and Particle Interactions
The University of Tokyo
2009-2024
We report the first direct measurement of hyperfine transition ground state positronium. The structure between ortho-positronium and para-positronium is about 203 GHz. develop a new optical system to accumulate 10 kW power using gyrotron, mode converter, Fabry-P\'erot cavity. has been observed with significance 5.4 standard deviations. probability measured be $A={3.1}_{\ensuremath{-}1.2}^{+1.6}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\text{ }\text{...
Quantum anisotropic exchange interactions in magnets can induce competitions between phases a different manner from those typically driven by geometrically frustrated interactions. We study one-dimensional spin-1/2 zigzag chain with such an interaction, Γ term, conjunction the Heisenberg find ground state phase diagram featuring multicritical point where five converge: uniform ferromagnet, two antiferromagnets, Tomonaga-Luttinger liquid, and dimer-singlet coexisting nematic order. This is...
We investigate the quantum spin-1/2 zigzag chain with frustrated ${J}_{1}\ensuremath{-}{J}_{2}$ Heisenberg interactions, incorporating additional off-diagonal exchange interactions known as $\mathrm{\ensuremath{\Gamma}}$ term, both and without an applied magnetic field. Based on density-matrix renormalization group calculation, we map out ground-state phase diagram that shows a variety of nonmagnetic phases including multicritical points several exactly solvable points. Upon introducing...
We performed high-resolution powder neutron diffraction experiments and discovered an elliptic helical incommensurate magnetic structure in the semiconducting rare-earth magnet YbCuS2, featuring effective spin-1/2 Yb$^{3+}$ ions that form a zigzag chain. Upon cooling sample to 0.2 K, we observed very weak peaks indexed with propagation vector k = [0, 0.305, 0] along The magnitude of moment is at least one-third smaller than expected value for Kramers doublet ground state. In applied field,...
We propose a framework to design concurrently frustration-free quantum many-body Hamiltonian and its numerically exact ground states on sufficiently large finite-size cluster in one two dimensions using an elementary matrix product state (MPS) representation. Our approach strategically chooses local Hamiltonian, which is arranged overlap with neighboring clusters designed lattice. The given as the sum of Hamiltonians by ensuring that there exists has submanifolds lowest-energy eigenstate...
Positronium is an ideal system for the research of bound state QED. New precise measurement orthopositronium decay rate has been performed with accuracy 150 ppm, and result combined last three 7.0401±0.0007 μs−1. It first to validate 2nd order correction. The Hyper Fine Splitting positronium sensitive higher corrections QED prediction also new physics beyond Standard Model via quantum oscillation into virtual photon. discrepancy 3.5σ found recently between measured values (O(α3)). might be...
The positronium spin conversion reaction induced by spin-orbit interaction is investigated. We obtain the rates during positronium-Xe and positronium-Kr collisions using Zeeman mixing of states. At thermal energies corresponding to room temperature, rate for due found be almost twice that pick-off reaction. also study energy dependence rate. mean controlled changing gas temperature in equilibrium. increases with collision energy.
The ground state hyperfine splitting of positronium, ΔHFS, is sensitive to high order corrections QED. A new calculation up O(α3) has revealed a 3.9 σ discrepancy between the QED prediction and experimental results. This might either be due systematic problems in previous experiments or contributions beyond Standard Model. We propose an experiment measure ΔHFS employing methods designed remedy errors which may have affected experiments. Our will provide independent check discrepancy....
We plan to directly measure the hyperfine structure of ground-state positronium. The between ortho-positronium and para-positronium is about 203 GHz. develop a new optical system accumulate 10 kW power using gyrotron Fabry-Pérot cavity, have already observed transition at frequency point 202.9 probability measured be A = 3.1 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1.2</inf> <sup xmlns:xlink="http://www.w3.org/1999/xlink">+1.6</sup> ×10...
Positronium is an ideal system for the research of QED. The hyperfine splitting positronium sensitive to higher order correction QED and new physics beyond Standard Model via a vacuum oscillation. method calculations has revealed 3.5σ discrepancy between prediction previous measurements. It might be because or experimental systematic uncertainties (the effect unthermalized Ps nonuniformity magnetic fields). We present results first run future plan our precise measurement on HFS without these...