arXiv subjects

Satoshi Adachi

Publications and source records attributed to Satoshi Adachi.

5 recordsLinked to original sources

arXiv2025

A 55-nm SRAM Chip Scanning Errors Every 125 ns for Event-Wise Soft Error Measurement

We developed a 55 nm CMOS SRAM chip that scans all data every 125 ns and outputs timestamped soft error data via an SPI interface through a FIFO. The proposed system, consisting of the developed chip and particle detectors, enables event-wise soft error measurement and precise identification of SBUs and MCUs, thus resolving misclassifications such as Pseudo- and Distant MCUs that conventional methods cannot distinguish. An 80-MeV proton irradiation experiment at RARiS, Tohoku University verified the system operation. Timestamps between the SRAM chip and the particle detectors were successfully synchronized, accounting for PLL disturbances caused by radiation. Event building was achieved by determining a reset offset with sub-ns resolution, and spatial synchronization was maintained within several tens of micrometers.

physics.ins-det↗

arXiv2005

Universality in Dynamical Formation of Entanglement for Quantum Chaos

Dynamical formation of entanglement is studied for quantum chaotic bi-particle systems. We find that statistical properties of the Schmidt eigenvalues for strong chaos are well described by the random matrix theory of the Laguerre ensemble. This implies that entanglement formation for quantum chaos has universal properties, and does not depend on specific aspects of the systems.

quant-ph↗

arXiv2000

Divergence-free WKB method

A new semiclassical approach to linear (L) and nonlinear (NL) one-dimensional Schrödinger equation (SE) is presented. Unlike the usual WKB solution, our solution does not diverge at the classical turning point. For LSE, our zeroth-order solution, when expanded in powers of \hbar, agrees with the usual WKB solution. For NLSE, our zeroth-order solution includes quantum corrections to the Thomas-Fermi solution, thereby giving a smoothly decaying wave function into the forbidden region.

cond-mat↗

arXiv1997

Renormalization group and critical behaviour in gravitational collapse

We present a general framework for understanding and analyzing critical behaviour in gravitational collapse. We adopt the method of renormalization group, which has the following advantages. (1) It provides a natural explanation for various types of universality and scaling observed in numerical studies. In particular, universality in initial data space and universality for different models are understood in a unified way. (2) It enables us to perform a detailed analysis of time evolution beyond linear perturbation, by providing rigorous controls on nonlinear terms. Under physically reasonable assumptions we prove: (1) Uniqueness of the relevant mode around a fixed point implies universality in initial data space. (2) The critical exponent $β_{BH}$ and the unique positive eigenvalue $κ$ of the relevant mode is exactly related by $β_{BH} = β/κ$, where $β$ is a scaling exponent. (3) The above (1) and (2) hold also for discretely self-similar case (replacing ``fixed point'' with ``limit cycle''). (4) Universality for diffent models holds under a certain condition. According to the framework, we carry out a rather complete (though not mathematically rigorous) analysis for perfect fluids with pressure proportional to density, in a wide range of the adiabatic index $γ$. The uniqueness of the relevant mode around a fixed point is established by Lyapunov analyses. This shows that the critical phenomena occurs not only for the radiation fluid but also for perfect fluids with $1 < γ\lesssim 1.88$. The accurate values of critical exponents are calculated for the models.

gr-qc↗

arXiv1995

Critical behaviour in gravitational collapse of radiation fluid --- A renormalization group (linear perturbation) analysis ---

A scenario is presented, based on renormalization group (linear perturbation) ideas, which can explain the self-similarity and scaling observed in a numerical study of gravitational collapse of radiation fluid. In particular, it is shown that the critical exponent $β$ and the largest Lyapunov exponent ${\rm Re\, } κ$ of the perturbation is related by $β= ({\rm Re\, } κ) ^{-1}$. We find the relevant perturbation mode numerically, and obtain a fairly accurate value of the critical exponent $β\simeq 0.3558019$, also in agreement with that obtained in numerical simulation.

gr-qc↗