Faculty Profiles - TOJO Satoshi

写真a

TOJO Satoshi

Organization

Faculty of Science and Engineering Professor

Other responsible organization

Physics Course of Graduate School of Science and Engineering, Master's Program
Physics Course of Graduate School of Science and Engineering, Doctoral Program

Contact information

The inquiry by e-mail is 《here》

Homepage

https://www.phys.chuo-u.ac.jp/j/tojo/?enHome

External link

Degree

博士（工学） ( 京都大学 )
修士（工学） ( 京都大学 )

Education

2003.9

Kyoto University Graduate School, Division of Engineering doctor course completed
1999.3

Kyoto University Graduate School, Division of Engineering master course completed
1997.3

Kyoto Institute of Technology Faculty of Engineering and Design graduated

Research History

2021.4 - 　

"Professor, Faculty of Science and Engineering, Chuo University"
2012.4 - 2021.3

"Associate Professor, Faculty of Science and Engineering, Chuo University"
2007.4 - 2012.3

"Assistant Professor, Faculty of Science, Gakushuin University"
2006.4 - 2007.3

"Research Associate, Faculty of Science, Gakushuin University"
2005.4 - 2006.3

"Postdoctoral Researcher, CREST, JST"
2004.4 - 2005.3

"COE Researcher, Graduate School of Science, Kyoto University"
2003.10 - 2004.3

"Postdoctoral Researcher, International Innovation Center, Kyoto University"
2003.10 - 2004.3

京都大学国際融合創造センター創造部門産学官連携研究員
1999.4 - 2000.8

Fujitsu Limited

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Professional Memberships

The Japan Society of Applied Physics
日本物理学会

Research Interests

Laser Cooling
Quantum Optics
Quantum Electronics
near-field optics

Research Areas

Natural Science / Semiconductors, optical properties of condensed matter and atomic physics / 原子・分子・量子エレクトロニクス
Nanotechnology/Materials / Optical engineering and photon science / "Optical engineering, Photon science"

Papers

Effective trapping of cold atoms using dipole and radiative forces in an optical trap Reviewed

Taro Mashimo, Masashi Abe, Satoshi Tojo

Physical Review A 100 ( 6 ) 063426-1 - 063426-7 2019.12

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Language：English Publishing type：Research paper (scientific journal) Publisher：American Physical Society

DOI： 10.1103/PhysRevA.99.053420

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Quantitative investigation of the Zeeman and Paschen-Back effects of the hyperfine structure in the rubidium 5 ^2 S_{1/2} - 5 ^2 D_{5/2} two-photon transition Reviewed

Masashi Abe, Ryohei Itoyama, Yuta Komiyama, Takuma Ito, Taro Mashimo, Satoshi Tojo

Physical Review A 99 ( 5 ) 053420-1 - 053420-8 2019.5

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Language：English Publishing type：Research paper (scientific journal) Publisher：American Physical Society

DOI： 10.1103/PhysRevA.99.053420

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Loading of atoms into an optical trap with high initial phase-space density Reviewed

Kosuke Shibata, Shota Yonekawa, Satoshi Tojo

PHYSICAL REVIEW A 96 ( 1 ) 013402-1 - 013402-6 2017.7

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Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

We report a method for loading cold atoms into an optical trap with high initial phase-space density (PSD). When the trap beam is overlapped with atoms in optical molasses of optimized parameters including large cooling beam detuning compared with conventional detuning used for a magneto- optical trap (MOT), more than 3 x 10(6) rubidium atoms with an initial temperature less than 20 mu K are loaded into a single beam trap. The obtained maximum initial PSD is estimated to be 1.1 x 10(-3), which is one or two orders of magnitude greater than that achieved with the conventional loading into an optical trap from atoms in a MOT. The proposed method is promising for creating a quantum gas with a large number of atoms in a short evaporation time.

DOI： 10.1103/PhysRevA.96.013402

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Excitation enhancement in electric multipole transitions near a nanoedge Reviewed

Kosuke Shibata, Satoshi Tojo, Daniel Bloch

OPTICS EXPRESS 25 ( 8 ) 9476 - 9489 2017.4

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Language：English Publishing type：Research paper (scientific journal) Publisher：OPTICAL SOC AMER

We investigate enhancement of electric multipole excitations of atoms in the vicinity of an object with a nanoscale edge resulted from a large electromagnetic field gradient. We calculate the excitation efficiencies of a Rb atom around a nanoedge and find the excitations are enhanced by several orders of magnitude. The efficiencies with the change in the magnetic quantum number resolved are also examined. Each resolved efficiency shows rotationally symmetric spatial distribution, with continuous modification in shape from the far field to the near field. Furthermore, we estimate photon emission rates accompanied with multipole excitations in alkali (Rb and Cs) atoms and discuss the possibility to observe the enhancement in the multipole excitation in cold atoms. (C) 2017 Optical Society of America

DOI： 10.1364/OE.25.009476

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Optically controlled magnetic-field etching on the nano-scale Reviewed

Takashi Yatsui, Toshiki Tsuboi, Maiku Yamaguchi, Katsuyuki Nobusada, Satoshi Tojo, Fabrice Stehlin, Olivier Soppera, Daniel Bloch

LIGHT-SCIENCE & APPLICATIONS 5 ( 3 ) e16054-1 - e16054-7 2016.3

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Language：English Publishing type：Research paper (scientific journal) Publisher：CHINESE ACAD SCIENCES, CHANGCHUN INST OPTICS FINE MECHANICS AND PHYSICS

Electric and magnetic fields play an important role in both chemical and physical reactions. However, since the coupling efficiency between magnetic fields and electrons is low in comparison with that between electric fields and electrons in the visible wavelength region, the magnetic field is negligible in photo-induced reactions. Here, we performed photo-etching of ZrO2 nano-stripe structures, and identified an etching-property polarisation dependence. Specifically, the etching rate and etched profiles depend on the structure width. To evaluate this polarisation-dependent etching, we performed numerical calculations using a finite-difference time-domain method. Remarkably, the numerical results revealed that the polarisation-dependent etching properties were determined by the magnetic field distributions, rather than the electric field distributions. As nano-scale structures induce a localised magnetic field, the discovery of this etching dependence on the magnetic field is expected to introduce a new perspective on advanced nano-scale structure fabrication.

DOI： 10.1038/lsa.2016.54

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Cartographier un faisceau focalisé au delà de l'approximation paraxiale avec des transitions quasi-interdites : transfert du moment orbital, superchiralité, ...

Daniel Bloch, Vasily Klimov, Martial Ducloy, Pedro Chaves de, Souza Segundo, Satoshi Tojo, Jose R Rios Leite

PAMO-JSM 2014 Reims hal - 01022528 2014.7

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Language：French Publishing type：Research paper (conference, symposium, etc.) Publisher：Physique Atomique, Moléculaire et Optique - Journées de Spectroscopie Moléculaire

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Controlling phase separation of binary Bose-Einstein condensates via mixed-spin-channel Feshbach resonance Reviewed

Satoshi Tojo, Yoshihisa Taguchi, Yuta Masuyama, Taro Hayashi, Hiroki Saito, Takuya Hirano

PHYSICAL REVIEW A 82 ( 3 ) 033609 - 1-5 2010.9

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Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

We investigate controlled phase separation of a binary Bose-Einstein condensate in the proximity of a mixed-spin-channel Feshbach resonance in the vertical bar F = 1, m(F) = +1 > and vertical bar F = 2, mF = -1 > states of Rb-87 at a magnetic field of 9.10 G. Phase separation occurs on the lower-magnetic-field side of the Feshbach resonance while the two components overlap on the higher-magnetic-field side. The Feshbach resonance curve of the scattering length is obtained from the shape of the atomic cloud by comparison with the numerical analysis of coupled Gross-Pitaevskii equations.

DOI： 10.1103/PhysRevA.82.033609

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Dynamics of Quadruply Quantized Vortices in Rb-87 Bose-Einstein Condensates Confined in Magnetic and Optical Traps Reviewed

Takeshi Kuwamoto, Hayato Usuda, Satoshi Tojo, Takuya Hirano

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 79 ( 3 ) 034004 - 1-5 2010.3

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Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

We studied the dynamics of quadruply quantized vortices in Rb-87 Bose-Einstein condensates. Vortices were created in magnetically trapped condensates with hyperfine spin F = 2 by employing topological phase imprinting technique, wherein the direction of atomic spin is adiabatically reversed by applying a bias magnetic field. Vortices were observed for a holding time of up to 10 ms. Disappearance of the vortices was attributed to considerable expansion and excitation of the condensates, which were caused by the distortion of the magnetic potential. In order to observe the long-term behavior of the vortices, we transferred the condensates to a crossed-type optical dipole force trap after creating the vortices. In this case, the vortices were observed for a holding time of up to 22 ms. We also observed density profiles, which indicated the presence of split vortices.

DOI： 10.1143/JPSJ.79.034004

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Spin-dependent inelastic collisions in spin-2 Bose-Einstein condensates Reviewed

Satoshi Tojo, Taro Hayashi, Tatsuyoshi Tanabe, Takuya Hirano, Yuki Kawaguchi, Hiroki Saito, Masahito Ueda

PHYSICAL REVIEW A 80 ( 4 ) 042704 - 1-7 2009.10

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We studied spin-dependent two-body inelastic collisions in F=2 (87)Rb Bose-Einstein condensates both experimentally and theoretically. The (87)Rb condensates were confined in an optical trap and selectively prepared in various spin states in the F=2 manifold at a magnetic field of 3.0 G. The measured atom loss rates depend on the spin states of colliding atoms. We measured two fundamental loss coefficients for two-body inelastic collisions with total spins of 0 and 2. The loss coefficients determine the loss rates of all the spin pairs. The experimental results for mixtures of all spin combinations are in good agreement with numerical solutions of the Gross-Pitaevskii equations that include the effect of a magnetic field gradient.

DOI： 10.1103/PhysRevA.80.042704

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Line shapes of optical Feshbach resonances near the intercombination transition of bosonic ytterbium Reviewed

M. Borkowski, R. Ciurylo, P. S. Julienne, S. Tojo, K. Enomoto, Y. Takahashi

PHYSICAL REVIEW A 80 ( 1 ) 012715 - 1-14 2009.7

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The properties of bosonic ytterbium photoassociation spectra near the intercombination transition S-1(0)-P-3(1) are studied theoretically at ultralow temperatures. We demonstrate how the shapes and intensities of rotational components of optical Feshbach resonances are affected by mass tuning of the scattering properties of the two colliding ground-state atoms. Particular attention is given to the relationship between the magnitude of the scattering length and the occurrence of shape resonances in higher partial waves of the van der Waals system. We develop a mass-scaled model of the excited-state potential that represents the experimental data for different isotopes. The shape of the rotational photoassociation spectrum for various bosonic Yb isotopes can be qualitatively different.

DOI： 10.1103/PhysRevA.80.012715

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Collision dynamics between stretched states of spin-2 ⁸⁷Rb Bose–Einstein condensates Reviewed

S. Tojo, A. Tomiyama, M. Iwata, T. Kuwamoto, T. Hirano

Applied Physics B 93 ( 2-3 ) 403 - 407 2008.10

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Language：English Publishing type：Research paper (scientific journal) Publisher：Springer

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Hyperfine-structure-induced purely long-range molecules Reviewed

Katsunari Enomoto, Masaaki Kitagawa, Satoshi Tojo, Yoshiro Takahashi

PHYSICAL REVIEW LETTERS 100 ( 12 ) 123001 - 1-4 2008.3

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We have experimentally observed and theoretically identified a novel class of purely long-range molecules. This novel purely long-range state is formed due to a very weak hyperfine interaction that is usually treated only as a small perturbation in molecular spectra. Photoassociation spectroscopy of ultracold ytterbium ((171)Yb) atoms with the (1)S(0)-(3)P(1) intercombination transition presents clear identification of molecular states and the shallowest molecular potential depth of about 750 MHz among the purely long-range molecules ever observed.

DOI： 10.1103/PhysRevLett.100.123001

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Determination of the s-wave scattering length and the C-6 van der Waals coefficient of Yb-174 via photoassociation spectroscopy Reviewed

K. Enomoto, M. Kitagawa, K. Kasa, S. Tojo, Y. Takahashi

PHYSICAL REVIEW LETTERS 98 ( 20 ) 203201 - 1-4 2007.5

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We report photoassociation spectroscopy of Yb-174 for the S-1(0)-P-1(1) transition at 1 mu K, where only the s-wave scattering state contributes to the spectra. The wave function of the s-wave scattering state is obtained from the photoassociation efficiency, and we determine that the C-6 potential coefficient is 2300 +/- 250 a.u. and the s-wave scattering length is 5.53 +/- 0.11 nm. Based on these parameters, we discuss the scattering properties of s- and d-wave states.

DOI： 10.1103/PhysRevLett.98.203201

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Dynamics of Bose-Einstein condensates in optical trap with internal degrees of freedom Reviewed

S. Tojo, M. Iwata, A. Tomiyama, T. Kuwamoto, T. Hirano

Conference on Lasers and Electro-Optics Europe - Technical Digest 2007

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Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/CLEOE-IQEC.2007.4386705

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High-resolution photoassociation spectroscopy of ultracold ytterbium atoms by using the intercombination transition Reviewed

S Tojo, M Kitagawa, K Enomoto, Y Kato, Y Takasu, M Kumakura, Y Takahashi

PHYSICAL REVIEW LETTERS 96 ( 15 ) 153201 - 1-4 2006.4

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We observed high-resolution photoassociation spectra of laser-cooled ytterbium (Yb) atoms in the spin-forbidden S-1(0)-P-3(1) intercombination line. The rovibrational levels in the 0(u)(+) state were measured for red detunings of the photoassociation laser ranging from 2.9 MHz to 1.97 GHz with respect to the atomic resonance. The rotational splitting of the vibrational levels near the dissociation limit were fully resolved due to the sub-MHz linewidth of the spectra in contrast to previous measurements using the spin-allowed singlet transition. In addition, from a comparison between the spectra of Yb-174 and those of Yb-176, a d-wave shape resonance for Yb-174 is strongly suggested.

DOI： 10.1103/PhysRevLett.96.153201

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Shift and broadening in attenuated total reflection spectra of the hyperfine-structure-resolved D2 line of dense rubidium vapor Reviewed

Rikio Kondo, Satoshi Tojo, Takashi Fujimoto, Masahiro Hasuo

Physical Review A - Atomic, Molecular, and Optical Physics 73 ( 6 ) 062504 - 1-7 2006

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Language：English Publishing type：Research paper (scientific journal) Publisher：The American Physical Society

We have observed attenuated total reflection at a glass/rubidium vapor interface in high precision. The atom density was from 3.8× 1020 to 3.7× 1021 m-3 and the angle of incidence was from 48.4 to 64.8°. Redshift and broadening of the reflection spectra were observed. The redshift depended on atom density, angle of incidence, light polarization and hyperfine structure. The observed broadening was attributed to the self-broadening of the resonance line. Calculation based on the Fresnel formula with a local index for the susceptibility of the vapor, which included the Lorentz local field correction and the modification of the wave vector of the evanescent light by the optically dense atomic vapor, was found to be in reasonable agreement with the experimental results. © 2006 The American Physical Society.

DOI： 10.1103/PhysRevA.73.062504

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Precision measurement of the oscillator strength of the cesium-6 S-2(1/2)-> 5 D-2(5/2) electric quadrupole transition in propagating and evanescent wave fields Reviewed

S Tojo, T Fujimoto, M Hasuo

PHYSICAL REVIEW A 71 ( 1 ) 012507 - 1-9 2005.1

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Hyperfine-structure-resolved absorption spectra of the 6 S-2(1/2) --> 5 D-2(5/2) of cesium atoms have been observed with a temperature-controlled cell and a diode laser. From a comparison with the absorption of the D-2 transition at the same atom density range, the oscillator strength of the electric quadrupole transition was determined to be (4.69 +/- 0.05) X 10(-7). Reflection spectra of the same transition have also been observed in the partial and total reflection regimes with a reflection cell. An increase in the apparent oscillator strength was observed for total reflection with an increase in the angle of incidence, by a factor up to 1.5 at theta(c) + 83.8 mrad and 2.4 at theta(c) + 107.5 mrad for s and p polarizations, respectively, where theta(c) is the critical angle. The observed enhancement is ascribed to the incidence-angle-dependent wave vector and polarization vector of the evanescent wave.

DOI： 10.1103/PhysRevA.71.012507

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Oscillator-strength enhancement of electric-dipole-forbidden transitions in evanescent light at total reflection Reviewed

S Tojo, M Hasuo

PHYSICAL REVIEW A 71 ( 1 ) 012508 - 1-6 2005.1

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The absorption line strengths of electric-dipole-forbidden (magnetic dipole and electric quadrupole) transitions have been calculated in the evanescent light field that accompanies the total reflection of light. Owing to the complex wave and polarization vectors of the evanescent light, the apparent oscillator strength is enhanced from that in the propagating light and the enhancement for the electric quadrupole transition depends on the polarization vector of the incident light. Separation of the contribution from each component of the wave and polarization vectors is proposed with a magnetic-sublevel-resolved measurement for the (s-d) electric quadrupole transition.

DOI： 10.1103/PhysRevA.71.012508

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Absorption enhancement of an electric quadrupole transition of cesium atoms in an evanescent field Reviewed

S Tojo, M Hasuo, T Fujimoto

PHYSICAL REVIEW LETTERS 92 ( 5 ) 053001 - 1-4 2004.2

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We have observed for the first time reflection spectra of an electric quadrupole transition for the cesium atom (6(2)S(1/2)-5(2)D(5/2)) line at an angle of incidence from theta(c)-11.9 to theta(c)+107.5 mrad, where theta(c) is the critical angle for total reflection. From a comparison with the calculated absorption in the attenuated total reflection, the oscillator strengths for s and p polarizations were found to increase with an increase in the angle of incidence by a factor up to 1.5 at theta(c)+83.8 mrad and 2.4 at theta(c)+107.5 mrad, respectively, in the experiment. The dependences of the observed enhancement on the angle of incidence were in good agreement with the calculated ones for the oscillator strength of the quadrupole transition in the evanescent light.

DOI： 10.1103/PhysRevLett.92.053001

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Attenuated total reflection of the rubidium D-2 line in optically dense vapor Reviewed

S Tojo, Y Murakami, M Hasuo, T Fujimoto

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 72 ( 5 ) 1069 - 1072 2003.5

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Language：English Publishing type：Research paper (scientific journal) Publisher：PHYSICAL SOC JAPAN

Absorption spectrum of the evanescent light at a glass/Rb vapor interface has been observed with atom density from 9 x 10(19) m(-3) to 5 x 10(20) m(-3). Absorption is as high as 60% at the peak of a hyperfine structure split line. The absorption spectrum of the experiment is compared with that of the calculation based on Fresnel's relation on the assumption of a homogeneous electric susceptibility of the vapor. Near the critical angle the calculation which incorporates the Lorentz-Lorenz local-field correction reproduces the experimental red shift only partly.

DOI： 10.1143/JPSJ.72.1069

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Electron capture cross sections of H(2p) level in the intermediate velocity regime of H+-Na(3s), Na*(3p) collisions Reviewed

R Okasaka, S Asada, K Naemura, Y Seo, S Tojo, Y Matsumura

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 68 ( 10 ) 3248 - 3253 1999.10

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We measured electron capture cross sections of H(2p) level as functions of collision velocity by the observation of Lyman-alpha line emitted from decaying H(2p) atoms, in H+-Na(3s), and -Na*(3p) collisions. Excited sodium atoms were generated by optical excitation with a tunabe dye-laser and the energy of incident protons was in the range of 1-16 keV. The measured results are consistent with previous experiments if they exist and with theoretical calculations. The characteristic dependences on collision velocity of the cross sections were reproduced by the velocity-matching model in which the characteristics of the intermediate velocity collision were taken into account.

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Behaviors of excitation cross sections in the intermediate velocity regime on ion-atom collisions Reviewed

R Okasaka, Y Seo, S Tojo, Y Matsumura

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 38 ( 3A ) 1564 - 1568 1999.3

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Language：English Publishing type：Research paper (scientific journal) Publisher：JAPAN J APPLIED PHYSICS

We studied the behaviors of excitation cross sections and electron capture cross sections as functions of collision velocity using previous data of various collision systems. The structures peculiar to the intermediate velocity regime were recognized on the excitation cross sections. Close correlation of the excitation cross section to the electron capture cross section and a relaxation time longer than that for the electron capture process characterize the excitation process in the intermediate velocity regime. A model consisting of a two-step electron transfer process well explains the characteristics of the excitation cross sections in the intermediate velocity regime.

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MISC

22pTD-5 Mixing dynamics of binary ^<87>Rb Bose-Einstein condensates in an optical trap

Taguchi Y., Tanabe T., Kurihara M., Suzuki Y., Tojo S., Hirano T.

Meeting abstracts of the Physical Society of Japan 65 ( 1 ) 205 - 205 2010.3

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Influence of ground-state scattering properties on photoassociation spectra near the intercombination line of bosonic ytterbium Reviewed

M. Borkowski, R. Ciurylo, P. S. Julienne, S. Tojo, K. Enomoto, Y. Takahashi

20TH INTERNATIONAL CONFERENCE ON SPECTRAL LINE SHAPES 1290 34 - + 2010

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We study theoretically the properties of photoassociation spectra near the S-1(0)-P-3(1) intercombination line of bosonic ytterbium. We construct a mass scaled model of the excited state interaction potential that well describes bound state energies obtained in a previous photoassociation experiment. We then use it to calculate theoretical photoassociation spectra in a range of ultracold temperatures using semianalytical theory developed by Bohn and Julienne.
Photoassociation spectra not only give us the energies of excited bound states, but also provide information about the behavior of the ground state wavefunction. In fact, it can be shown that within the so-called reflection approximation the line intensity is proportional to the ground state wavefunction at the transition's Condon point. We show that in the case of ytterbium, the rotational structure of the photoassociation spectra depends heavily on the behavior of the ground-state wavefunction. The change of the scattering length from one isotope to another and the resulting occurence of shape resonances in higher partial waves determines the appearance and disapperance of rotational components, especially in the deeper lying states, whose respective Condon points lie near the ground state centrifugal barrier. Thus, photoassociation spectra differ qualitatively between isotopes.

DOI： 10.1063/1.3517578

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27aZF-2 Dynamics of ^<87>Rb F=2 BEC in one dimensional optical lattice

Tanabe T., Taguchi Y., Tojo S., Hirano T.

Meeting abstracts of the Physical Society of Japan 64 ( 2 ) 89 - 89 2009.8

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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27aZF-4 Controlling phase-separations of binary ^<87>Rb Bose-Einstein condensates by Feshbach resonance

Tojo S., Tanabe T., Taguchi Y., Hirano T.

Meeting abstracts of the Physical Society of Japan 64 ( 2 ) 89 - 89 2009.8

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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30pSD-4 Phase separation of ^<87>Rb BEC in clock states

Hayashi T., Tojo S., Tanabe T., Inoue E., Hiraro T.

Meeting abstracts of the Physical Society of Japan 64 ( 1 ) 186 - 186 2009.3

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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20aZA-4 Dynamics of ^<87>Rb F=2 BEC in one dimensional optical lattice

Tanabe T., Inoue E., Hayashi T., Tojo S., Hirano T.

Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 95 - 95 2008.8

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25pQD-4 Collision dynamics of ^<87>Rb spin-2 Bose-Einstein condensates

Tojo S., Hayashi T., Tanabe T., Hirano T.

Meeting abstracts of the Physical Society of Japan 63 ( 1 ) 186 - 186 2008.2

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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20aXK-5 Dynamics of binary Bose-Einstein compensates in an optical trap

Iwata M., Hamasaki K., Tojo S., Kuwamoto T., Hirano T.

Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 157 - 157 2007.2

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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20aXK-6 Spinor dynamics in a spin-2 bose condensate

Tomiyama A., Iwata M., Kuwamoto T., Tojo S., Hirano T.

Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 157 - 157 2007.2

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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27aXS-4 Self-broadening of attenuated total reflection spectra at a Rb vapor/glass interface

Kondo R., Tojo S., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 59 ( 1 ) 150 - 150 2004.3

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Attenuated total reflection spectra at a Rb vapor/glass interface in high atom density regime

Kondo R., Tojo S., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 58 ( 2 ) 137 - 137 2003.8

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Oscillator strength of Cs electric quadrupole transition in an evanescent field

Tojo S., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 58 ( 2 ) 137 - 137 2003.8

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Polarization spectroscopy in absorption of evanescent light by Cs atoms in an optically forbidden transition

Tojo S., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 58 ( 1 ) 170 - 170 2003.3

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Atom density dependence of the attenuated total reflection spectra at a glass/Rb vapor interface

Kondo R., Tojo S., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 58 ( 1 ) 170 - 170 2003.3

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Absorption experiment of evanescent light by Cs atoms in an optically forbidden transition

Tojo S, Hasuo M, Fujimoto T

Meeting abstracts of the Physical Society of Japan 57 ( 2 ) 109 - 109 2002.8

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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25pWM-13 Absorption spectra of evanescent fight by Cs atoms in an optically forbidden transition

Tojo S., Hasuo M., Fujimoto T

Meeting abstracts of the Physical Society of Japan 57 ( 1 ) 142 - 142 2002.3

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Absorption of evanescent light by Cs atoms of an optically forbidden transition

Tojo S., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 56 ( 2 ) 57 - 57 2001.9

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Language：Japanese Publisher：The Physical Society of Japan (JPS)

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Spectrum of the attenuated total reflection at a glass/Rb vapor interface

Tojo S., Shimamoto A., Hasuo M., Fujimoto T.

Meeting abstracts of the Physical Society of Japan 56 ( 1 ) 136 - 136 2001.3

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Presentations

Two photon spectroscopy of ultracold rubidium atoms near dielectric surface

Taro Mashimo, Go Tanaka, Sakura Seta, Masashi Abe, Satoshi Tojo

International Conference on Atomic Physics 2018 2018.7

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Language：English Presentation type：Poster presentation

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Excitation enhancement in optical forbidden transitions near nanostructure

Satoshi Tojo, Taro Mashimo, Masashi Abe, Daniel Bloch

International Conference on Atomic Physics 2018 2018.7

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Language：English Presentation type：Poster presentation

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Zeeman and Paschen-Back resolved spectra of rubidium 5S-5D two-photon excitation

Ryohei Itoyama, Yuta Komiyama, Taro Mashimo, Kosuke Shibata, Masashi Abe, Satoshi Tojo

The 30th International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC XXX) 2017.7

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Laser spectroscopy of gaseous atoms in local field using optical forbidden transitions Invited International conference

Satoshi Tojo

23rd International Conference on Spectral Line Shapes (ICSLS 23) 2016.6

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Counter superflow in two-component Bose-Einstein condensates

東條賢ほか

物性研究所短期研究会「量子凝縮系におけるdefectsおよびtopology」／物性研究所 2012.1

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多成分ボースアインシュタイン凝縮体を用いた量子渦生成

東條賢ほか

対称性の破れた凝縮系におけるトポロジカル量子現象第2回領域研究会概要集／対称性の破れた凝縮系におけるトポロジカル量子現象領域事務局 2011.12

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Language：Japanese Presentation type：Oral presentation (general)

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スピノルボース凝縮体を用いた新奇量子渦生成へ向けて

東條賢, 田口義久, 増山雄太, 平野琢也

対称性の破れた凝縮系におけるトポロジカル量子現象第1回領域研究会概要集／対称性の破れた凝縮系におけるトポロジカル量子現象領域事務局 2010.12

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Search for "trimmer" Bose-Einstein condensate International conference

S. Tojo, T. Tanabe, Y. Taguchi, T. Hirano

Novel Spin Pairing 2009, Abstract book 2009.9 Novel Spin Pairing 2009 Organizing Committee

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Controlling phase-separation of binary Bose-Einstein condensates by mixex-spin channel Feshbach resonance International conference

S. Tojo

The 18th International Laser Physicis Workshop (LPHYS'09) 2009.7 Steering committee of LPHYS'09

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Controlling phase-separation of binary Bose-Einstein condensates near mixed-spin-channel Feshbach resonance International conference

S. Tojo, T. Tanabe, Y. Taguchi, T. Hirano

Cold Atom and Molecules :Collisions, Field-Effects, and Applications 2009.6 Japan-US seminar Committee

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スピン自由度を持つ希薄原子気体のボース-アインシュタイン凝縮

東條賢, 桑本剛, 平野琢也

レーザー学会学術講演会第29回年次大会・講演概要集／レーザー学会 2009.1

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Properties and dynamics of Bose-Einstein condensates with internal degrees of freedom

平野琢也

スーパークリーン物質で実現する新しい量子相の物理平成20年研究成果発表会アブストラクト／スーパークリーン物質で実現する新しい量子相の物理事務局 2008.12

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Collision dynamics of spin-2 Bose-Einstein condensates with internal degrees of freedom

東條賢ほか

スーパークリーン物質で実現する新しい量子相の物理平成20年研究成果発表会アブストラクト／スーパークリーン物質で実現する新しい量子相の物理事務局 2008.12

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Dynamics of ⁸⁷Rb spin-2 BEC in one dimensional optical lattice

田邉達良

スーパークリーン物質で実現する新しい量子相の物理平成20年研究成果発表会アブストラクト／スーパークリーン物質で実現する新しい量子相の物理事務局 2008.12

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Dynamics of ⁸⁷Rb binary Bose-Einstein condensates in clock states

林太郎ほか

スーパークリーン物質で実現する新しい量子相の物理平成20年研究成果発表会アブストラクト／スーパークリーン物質で実現する新しい量子相の物理事務局 2008.12

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Absorption of Evanescent Light by Cs Atoms in an Optically Forbidden Transition International conference

S. Tojo, M. Hasuo, T. Fujimoto

The 7th International Conference on Near-field Optics and Related Techniques 2002.8 NFO7 Committee

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Research Projects

冷却原子・分子の量子エンタングル状態を用いたＥＤＭ探索

Grant number：23H01197 2023.4 - 2026.3

日本学術振興会科学研究費助成事業基盤研究(B) 東京大学

青木貴稔, 東條賢, 松尾由賀利, 阿部穣里, 酒見泰寛

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Grant amount： \18980000 （ Direct Cost: \14600000 、 Indirect Cost： \4380000 ）

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薄膜状原子波プローブによるナノ光磁場相互作用の探索

Grant number：19K03704 2019.4 - 2023.3

日本学術振興会科学研究費助成事業基盤研究(C) 中央大学

東條賢, 阿部真志

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Grant amount： \4420000 （ Direct Cost: \3400000 、 Indirect Cost： \1020000 ）

制御性の高いレーザー冷却原子を”原子波プローブ”として用いて、誘電体表面近傍に誘起されるナノ領域における光磁気的な相互作用探索を目指している。[1]冷却原子によって波の性質を有する薄膜状の原子波に、[2]光磁場を透磁率変化により転写し、[3]光磁場による新しい量子操作へと発展する。初年度では薄膜原子波プローブ測定の技術確立を，2年目では原子波の輸送および光磁場検出のための光源開発と照射光の空間モード制御を準備し、3年目では特に空間モード制御によって軌道角運動量を有するラゲールガウス光（LG光）の整備を行ってきた。LG光は主に光電場がドーナツ型分布している一方で、特異な空間モードでは光電場のない中心部分に光磁場が存在する。これにより[3]光磁場による新しい量子測定および量子操作に向けた研究として確立を目指してきた。
これまで[1]に必要な原子波の表面近傍への輸送，[2]に必要な光磁場を有する5P-6P遷移である911nm光の高強度化と照射実験，[3]のLG光の整備を行ってきた。最終年度ではこれらの統合および実験技術の確立と、光磁場測定の実施を試みる。
[1]については冷却原子を表面近傍の光定在波を用いて表面から数μm近傍への輸送を実現している。さらなる表面近傍への輸送として、打ち上げ法（ファウンテン法）を運用する一方で、重力を利用した落下による表面近傍輸送を試みてきた。表面近傍での薄膜原子波による光電磁場測定の確立を行う。
[2]については911nm光の照射実験を安定運用してきた。今年度では光アンプを安定運用し、数百mW程度の高強度光源を用いて[1]の実験との統合化を目指してきた。
[3]についてはLG光の整備および光学禁制遷移を用いた照射実験を行った。また5P-5D遷移である776nm光の非線形光学測定を行い、LG光の光圧のモード依存性への応用を検討してきた。

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Experimental research on higher-order interaction between cold atoms and localized light by optical near-field

Grant number：15K05234 2015.4 - 2018.3

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C) Chuo University

Tojo Satoshi, SHIBATA Kosuke, ABE Masashi

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Grant amount： \4550000 （ Direct Cost: \3500000 、 Indirect Cost： \1050000 ）

We research on higer order interaction between ultracold rubidium atoms and localized light by optical near-field. It is necessary to establish the observation system of higer-order interaction, namely optical forbidden transitions, of cold atoms near the dielectric surface. We succeed the observation of emission from trapped cold atoms via optical forbidden and optical-optical double resonant transitions. Due to change different wavelength of emission from excitations, the observed emission indicate to be improved signal-to-noise ratio in spite of weaker transition in serveral orders of magnetude in comparison with allowed ones. In view of theoretical reserach, we calculate transition probabilities of optical forbidden transitions near a nanoedge, and the results show highly enhancement of transisions in several orders of magnitude due to high-order interactions. In our experiment, we confirm several factor magnification of forbidden transitions of oxygen molecules near nano-edges.

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微小磁場中スピノルボーズ凝縮体を用いた新奇量子渦の実現

Grant number：23103514 2011.4 - 2013.3

日本学術振興会科学研究費助成事業新学術領域研究(研究領域提案型)

東條賢

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Grant amount： \5980000 （ Direct Cost: \4600000 、 Indirect Cost： \1380000 ）

2012年度より現大学へ異動したためデータ解析および装置の再製作を主として行った。
スピノル凝縮実験結果の解析においては前年度で問題のあったボーズ凝縮原子数の再評価を行った。まず、光トラップ中におけるボーズ凝縮の原子数評価を解析した。スピノルボーズ凝縮実験では、1成分ボーズ凝縮を磁気トラップで生成したのち、光トラップへ導入する必要がある。この際、主に環境温度変動によって磁気トラップ中ボーズ凝縮体の原子数が20％程度揺らいでいた。解析の結果、光トラップへの導入時に磁気トラップとの中心点の空間的なずれによって原子数が不安定になっていることがわかった。前年度までに予想した温度および磁場安定化では達成できなかった安定度については、微小変動磁場を生じる電源装置をはじめとした装置群のノイズ対策によって原子数の安定度向上を見込めた。
装置の再製作については、光源、真空装置、磁場制御の改良を行った。光源については自作半導体レーザー装置を改良し温度の高安定化を実現できた。これにより冷却光および観測光の強度安定化が実現できた。また回路作製のために基板作製機を導入し、レーザー周波数を100kHz程度まで制御装置を制作できた。環境磁場制御用の自作磁気プローブ製作と性能評価を行い1mG以下まで計測できることを確認できた。
前年に行った量子渦生成実験データの解析を行った。光スプーンによる量子渦生成においてスプーン回転の周波数依存のデータを取得していたが、解析により量子渦の渦度および渦の個数の評価を行った。結果、臨界回転数付近で渦度1の量子渦が2,3個生じており, 回転数による依存性は主として生じていなかった。ボーズ凝縮の重心運動にも着目し評価すると渦の個数の多いときは重心運動の振れ幅が大きい傾向を確認した。凝縮体のトラップ中の運動エネルギーが量子渦の生成個数に影響を与えている可能性を示すことができた。

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Interference instability by counter-superflow of two-component Bose-Einstein condensates

Grant number：23740308 2011 - 2012

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

TOJO Satoshi

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Grant amount： \4420000 （ Direct Cost: \3400000 、 Indirect Cost： \1020000 ）

For generation of interface instability in two component Bose-Einstein condensates, it is necessary to reduce differences of number-of-atoms between two spin states. We improved environment magnetic field fluctuation so that the differen

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Study on superfluidity of atomic gases with internal degrees of freedom.

Grant number：17071005 2005 - 2009

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Priority Areas

UEDA Masahito, HIRANO Takuya, SAITO Hiroki, KUWAMOTO Takeshi, TOJO Satoshi, KAWAGUCHI Yuki, TOJO Satoshi, KAWAGUCHI Yuki

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Grant amount： \43700000 （ Direct Cost: \43700000 ）

We studies superfluid properties of Bose-Einstein condensates (BECs) with internal degrees of freedom. We have numerically demonstrated that by changing an external magnetic field spin vortices are spontaneously generated. This provides an atomic-gas demonstration of the Kibble-Zurek mechanism. We have also demonstrated that exotic topological excitations such as knots and non-Abelian vortices can be created in spinor BECs.

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Quantum vortices of Bose-Einstein condensate with internal degrees of freedom

Grant number：19740248 2007 - 2008

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B) Gakushuin University

TOJO Satoshi

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Grant amount： \3840000 （ Direct Cost: \3300000 、 Indirect Cost： \540000 ）

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