arXiv subjects

Yuki Miyazawa

Publications and source records attributed to Yuki Miyazawa.

8 recordsLinked to original sources

arXiv2026

Theoretical Proposal of a Digital Closed-Loop Thermal Atomic-Beam Interferometer for High-Bandwidth, Wide-Dynamic-Range, and Simultaneous Absolute Acceleration-Rotation Sensing

We present a theoretical proposal and simulation study of a digital closed-loop thermal atomic-beam interferometer for inertial navigation applications. The scheme synchronizes phase biasing with momentum-kick reversal through the atomic transit time, extracting four interferometric phases to suppress Raman beam path-length errors, while two-photon detuning feedback maintains a pseudo-inertial frame and eliminates cross-coupling. The interferometer enables simultaneous measurements of acceleration and rotation based on an absolute, atom-interferometric reference, with high bandwidth and a wide dynamic range. Numerical simulations verify that acceleration and angular velocity can be measured simultaneously and independently in real time without cross-coupling, demonstrating the absolute, decoupled nature of the proposed measurement scheme. We further evaluate the noise-limited performance of the sensor and obtain sensitivities of $3{\rm μm / s^2 / \sqrt{Hz}}$ (velocity random walk) and $15{\rm μdeg / \sqrt{h}}$ (angular random walk) for a ${170}^{\circ}$ $^{85}$Rb beam and an interferometer arm length of 100~mm, surpassing the performance of sensors currently used in state-of-the-art inertial navigation systems.

physics.atom-ph↗

arXiv2025

Observation of the Einstein-de Haas Effect in a Bose-Einstein condensate

The Einstein-de Haas effect is a phenomenon in which angular momentum is transferred from microscopic spins to mechanical rotation of a rigid body. Here, we report the first observation of the Einstein-de Haas effect in a spinor-dipolar Bose-Einstein condensate where quantized vortices emerge in depolarized spinor components through coherent angular-momentum transfer from microscopic atomic spins to macroscopic quantized circulation. Experimental results clearly show that the spherical symmetry of the condensate is dynamically broken into the axisymmetry by an intrinsic magnetic dipole-dipole interaction.

cond-mat.quant-gas↗

arXiv2022

Simultaneous Suppression of Thermal Phase Noise and Relative Intensity Noise in a Fiber Optic Gyroscope

The short-term sensitivity of a kilometer-long fiber-optic gyroscope is limited mainly by thermal phase noise and relative intensity noise. Increasing the phase modulation frequency decreases the thermal phase noise but not the relative intensity noise since it behaves as white noise. Here, we propose and experimentally demonstrate that the angular random walk can be effectively decreased by suppressing relative intensity noise at the modulation frequency and its third-order harmonic using direct feedback to the drive current of a superluminescent diode. Our simultaneous suppression of thermal phase noise and relative intensity noise yields an angular random walk of $15\,μ\mathrm{deg}/\sqrt{\mathrm{h}}$ and a bias instability of $33\,μ\mathrm{deg}/\mathrm{h}$ using a fiber coil with a length of $5\,$km and an effective area of $280\,\mathrm{m^2}$ for a measurement time of 40 hours.

physics.optics↗

arXiv2022

Bose-Einstein Condensation of Europium

We report the realization of a Bose-Einstein condensate of europium atoms, which is a strongly dipolar species with unique properties, a highly symmetric $[\mathrm{Xe}]\ 4f^7 6s^2\ {}^8\mathrm{S}_{7/2}$ electronic ground state and a hyperfine structure. By means of evaporative cooling in a crossed optical dipole trap, we produced a condensate of ${}^{151}$Eu containing up to $5\times 10^4$ atoms. The scattering length of ${}^{151}$Eu was estimated to be $a_s = 110(4)\, a_\mathrm{B}$ by comparing the velocities of expansion of condensates with different orientations of the atomic magnetic moments. We observed deformation of the condensate in the vicinity of the Feshbach resonance at $1.32\,\mathrm{G}$ with a width of $10\,\mathrm{mG}$.

cond-mat.quant-gas↗

arXiv2021

Understanding one-body losses in magnetically trapped metastable europium atoms

We report the measurement of one-body loss rates for magnetically trapped metastable europium atoms and the study of their loss mechanism. The loss of atoms observed in a magneto-optical trap is not fully understood because of the indivisibility of the loss regarding optical pumpings due to the presence of cooling laser beams. We magnetically trapped the atoms by directly loading from the magneto-optical trap and observed almost identical one-body loss rates of approximately $2.6\,\mathrm{s^{-1}}$ for two isotopes: $\mathrm{{}^{151}Eu}$ and $\mathrm{{}^{153}Eu}$. Our rate-equation-based model, combined with loss rate measurements carried out with repumpers, shows that blackbody radiation at room temperature drives E1 transitions and induces the observed losses.

physics.atom-ph↗

arXiv2021

Narrow-line magneto-optical trap for europium

We report on the realization of a magneto-optical trap (MOT) for europium atoms using a narrow-line cooling transition with a natural linewidth of 97 kHz. Our starting point is continuous capturing and cooling of optically pumped metastable europium atoms. We have employed simultaneous MOT for the metastable and ground-state atoms. The trapped metastable atoms are successively pumped back to the ground state and then continuously loaded to the narrow-line MOT, where up to $4.7\times10^7$ atoms are captured. A spin-polarized sample at a temperature of $6\,\mathrm{μK}$ and with a peak number density of $2.2\times10^{11}\,\mathrm{cm^{-3}}$ is obtained through the compression process, resulting in a phase space density of $3\times10^{-5}$.

cond-mat.quant-gas↗

arXiv2018

Magneto-optical trapping of optically pumped metastable europium

We demonstrate laser cooling and magneto-optical trapping of europium. The atoms are optically pumped to a metastable state and then loaded from an atomic-beam source via conventional Zeeman slowing and magneto-optical trapping techniques using a $J=13/2\leftrightarrow J=15/2$ quasi-cyclic transition. The trapped populations contained up to $1\times 10^7$ atoms, and a two-body loss rate is estimated as $1\times10^{-10}\,\mathrm{cm^3/s}$ from the non-exponential loss of atoms at high densities. We also observed leakage out of the quasi-cyclic transition to the two metastable states with $J=9/2$ and $11/2$, which is adequate to pump the laser-cooled atoms back to the $J=7/2$ ground state.

cond-mat.quant-gas↗

arXiv2016

Measuring the branching ratios from the $y^8 {\rm P}_{9/2}$ state to metastable states in europium

We measure the branching ratios from the $y^8{\rm P}_{9/2}$ excited state to six metastable states of europium through fluorescence spectroscopy of an atomic beam. The sum of the six branching ratios is estimated to be $1.05(2)\times 10^{-3}$. This research provides us with insightful information to determine the feasibility of using the $a^8{\rm S}_{7/2} - y^8{\rm P}_{9/2}$ transition in order to implement the Zeeman slowing for europium atoms in the ground state. Based on this result, we also propose a scheme for Zeeman slowing and magneto-optical trapping, using a specific metastable state which has a cyclic transition.

cond-mat.quant-gas↗