arXiv subjects

S. Endoh

Publications and source records attributed to S. Endoh.

3 recordsLinked to original sources

arXiv2026

A Cryogenic Penning Trap Based on Permanent Magnets

We report on a Penning trap based on NdFeB permanent magnets operated at 4\,K with a magnetic field strength of 280\,mT. Reliable loading and confinement of protons, H$_2^+$ ions, and electrons was demonstrated with non-destructive single-particle detection sensitivity of protons and H$_2^+$ ions using superconducting image-current circuits. The axial frequency of individual particles reaches a shot-to-shot stability of 47 parts-per-billion comparable to that of state-of-the-art precision Penning-trap experiments. Measurements of the proton modified-cyclotron frequency show a shot-to-shot scatter of $0.14$ parts per million (p.p.m.), presently limited by millikelvin-level temperature fluctuations of the permanent-magnet assembly. We outline a route towards improving this performance by more than an order of magnitude. This development offers broad potential for axial-mode-related precision measurements and cost-efficient Penning-trap experiments, and represents an important step towards compact, scalable, and transportable antiproton-trap systems.

physics.atom-ph↗

arXiv2001

Stiffness of the Heisenberg Spin-Glass Model at Zero- and Finite-Temperatures in Three Dimensions

We examine the stiffness of the Heisenberg spin-glass (SG) model at both zero temperature (T=0) and finite temperatures ($T \ne 0$) in three dimensions. We calculate the excess energies at T=0 which are gained by rotating and reversing all the spins on one surface of the lattice, and find that they increase with the lattice size $L$. We also calculate the excess free-energies at $T \ne 0$ which correspond to these excess energies, and find that they increase with $L$ at low temperatures, while they decrease with increasing $L$ at high temperatures. These results strongly suggest the occurrence of the SG phase at low temperatures. The SG phase transition temperature is estimated to be $T_{\rm SG} \sim 0.19J$ from the lattice size dependences of these excess free-energies.

cond-mat.dis-nn↗

arXiv2000

Phase Transition of a Heisenberg Spin-Glass Model in Three Dimensions

We study the phase transition of the $\pm J$ Heisenberg model in three dimensions. Using a dynamical simulation method that removes a drift of the system, the existence of the spin-glass (SG) phase at low temperatures is suggested. The transition temperature is estimated to be $T_{\rm SG} \sim 0.18J$ from both equilibrium and off-equilibrium Monte-Carlo simulations. Our result contradicts the chirality mechanism of the phase transition reported recently by Kawamura which claims that it is not the spins but the chiralities of the spins that are ordered in Heisenberg SG systems.

cond-mat.dis-nn↗