Organization
School of Science Professor
Title
Professor
External link
FUJISAWA TOSHIMASA
News & Topics
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一次元プラズモン回路による高周波信号の量子化分配器を実現 整数・分数量子ホール効果を用いた新機能高周波素子
2021/01/08
Languages： Japanese
要点-高周波信号を正確な整数比で分配することができる量子化分配器を実現-磁場中の半導体でおこる量子ホール効果を用いて、電子の集団運動（プラズモン）を情報媒体とする一次元プラズモン回路で分配器を構成-正確な整数比で電荷を分配することができるため、高速で正確な信号伝達技術に活用が可能で、さらに新たなトポ
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電荷信号とスピン信号の波形計測を実現 ―超高速・低消費電力の次世代エレクトロニクス素子創出に道拓く―
2017/03/14
Languages： Japanese
要点 電荷信号とスピン信号の時間波形を計測できるスピン分解オシロスコープを実現 プラズモニクス、スピントロニクスにおける基本測定器として期待 朝永―ラッティンジャー液体におけるスピン電荷分離現象の直接観察に成功
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Spin-resolved oscilloscope for charge and spin signals
2017/03/14
Languages： English
Researchers at the Tokyo Institute of Technology (Tokyo Tech) and Nippon Telegraph and Telephone Corporation (NTT) have developed a spin-resolved oscilloscope. This device is a basic measuring instrument for plasmonics and spintronics, which are key technologies for future electronics applications. The coupling of light and electronic charges in plasmonics will pave the way for ultra-high-speed information processing, whereas spintronics will provide low-energy-consumption technology in a highly information-oriented society. The spin-resolved oscilloscope pioneers future spin-plasmonics, where ultra-high-speed low-energy-consumption devices will be achieved.
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Successful observation of elementary excitation processes in Tomonaga-Luttinger liquid
2014/11/07
Languages： English
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朝永-ラッティンジャー流体の励起素過程の観測に成功 -プラズモン回路の集積化に道-
2014/02/17
Languages： Japanese
東京工業大学大学院理工学研究科の鎌田大博士研究員と藤澤利正教授、日本電信電話株式会社物性科学基礎研究所の村木康二上席特別研究員らの共同研究グループは、半導体ナノ構造中において、朝永-ラッティンジャー流体の励起素過程の観測に世界で初めて成功しました。一次元プラズモン回路である量子ホールエッジチャネルを複数用いて、人工的な朝永-ラッティンジャー流体を形成し、プラズモン波束の反射波の時間分解測定を行うことによって観測しました。朝永-ラッティンジャー流体の励起素過程の観測は、複数の一次元プラズモン回路の間で信号が伝達されることを示しており、プラズモン集積回路への応用の道を開く成果といえます。この成果は英国時間2014 年2 月9 日PM6:00 に英国科学雑誌｢NatureNanotechnology（ネイチャーナノテクノロジー）｣のオンライン速報版で公開されました。
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グラフェンを用いたプラズモンの伝搬制御を世界で初めて実証 ～電子の波を利用したナノ領域での回路の高速化、超低消費電力化へ前進～
2013/01/17
Languages： Japanese
日本電信電話株式会社(本社：東京都千代田区、代表取締役社長：鵜浦博夫、以下 NTT)と国立大学法人東京工業大学(東京都目黒区、学長：三島良直、以下 東工大)は、電子の移動度が高いなどの特性から近年注目されているグラフェンを利用することにより、電子の波であるプラズモンの伝搬速度を二桁に渡り制御できることを世界で初めて実証しました。従来、プラズモンの研究では金属が用いられていましたが、NTT と東工大はグラフェンに着目し電子密度等を変化させることにより伝搬速度制御を可能としました。 本成果を用いることにより、光信号をプラズモンの形でナノメートルサイズに閉じ込め制御することが可能となります。将来的には、チップ内の電子回路をプラズモン回路に置き換える事でコンピュータやネットワーク機器の大幅な高速化・低消費電力化が出来ると期待されています。
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Quantum logic: Multi-functioning
2011/03/31
Languages： English
Research Areas
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Natural Science / Semiconductors, optical properties of condensed matter and atomic physics
Papers
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Quantized charge fractionalization at quantum Hall Y junctions in the disorder dominated regime
Chaojing Lin, Masayuki Hashisaka, Takafumi Akiho, Koji Muraki, Toshimasa Fujisawa
Nature Communications 12 ( 1 ) 2021.12
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Plasmon modes of coupled quantum Hall edge channels in the presence of disorder-induced tunneling
Toshimasa Fujisawa, Chaojing Lin
Physical Review B 2021.4
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Two-step breakdown of a local ν=1 quantum Hall state
Masayuki Hashisaka, Koji Muraki, Toshimasa Fujisawa
Physical Review B 101 ( 4 ) 2020.1
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Ballistic hot-electron transport in a quantum Hall edge channel defined by a double gate
Shunya Akiyama, Taichi Hirasawa, Yuya Sato, Takafumi Akiho, Koji Muraki, Toshimasa Fujisawa
Applied Physics Letters 2019.12
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Quantum anti-dot formed with an airbridge gate in the quantum Hall regime
Ryota Eguchi, Eiki Kamata, Chaojing Lin, Hiromitsu Aramaki, Toshimasa Fujisawa
Applied Physics Express 12 ( 6 ) 2019.6
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Charge equilibration in integer and fractional quantum Hall edge channels in a generalized Hall-bar device
Chaojing Lin, Ryota Eguchi, Masayuki Hashisaka, Takafumi Akiho, Koji Muraki, Toshimasa Fujisawa
PHYSICAL REVIEW B 99 ( 19 ) 2019.5
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Spectroscopic study on hot-electron transport in a quantum Hall edge channel
Tomoaki Ota, Shunya Akiyama, Masayuki Hashisaka, Koji Muraki, Toshimasa Fujisawa
PHYSICAL REVIEW B 99 ( 8 ) 2019.2
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Coupling between quantum Hall edge channels on opposite sides of a Hall bar
Ngoc Han Tu, Masayuki Hashisaka, Takeshi Ota, Yoshiaki Sekine, Koji Muraki, Toshimasa Fujisawa, Norio Kumada
SOLID STATE COMMUNICATIONS 283 32 - 36 2018.11
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Electronic energy spectroscopy of monochromatic edge magnetoplasmons in the quantum Hall regime
Tomoaki Ota, Masayuki Hashisaka, Koji Muraki, Toshimasa Fujisawa
Journal of Physics: Condensed Matter 30 ( 34 ) 345301 - 345301 2018.8
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Signatures of a Nonthermal Metastable State in Copropagating Quantum Hall Edge Channels Reviewed
Itoh, K., Nakazawa, R., Ota, T., Hashisaka, M., Muraki, K., Fujisawa, T.
Physical Review Letters 120 ( 19 ) 2018
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Lin, C. J., Morita, K., Muraki, K., Fujisawa, T.
Japanese Journal of Applied Physics 57 ( 4 ) 2018
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Dissipative Landau-Zener transition in double quantum dot under sinusoidal potential modulation Reviewed
Ota, T., Hitachi, K., Muraki, K., Fujisawa, T.
Applied Physics Express 10 ( 11 ) 2017
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Ota, T., Hashisaka, M., Muraki, K., Fujisawa, T.
Journal of Physics-Condensed Matter 29 ( 22 ) 2017
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Two-electron double quantum dot coupled to coherent photon and phonon fields Reviewed
Sato, Y., Chen, J. C. H., Hashisaka, M., Muraki, K., Fujisawa, T.
Physical Review B 96 ( 11 ) 2017
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Waveform measurement of charge- and spin-density wavepackets in a chiral Tomonaga-Luttinger liquid Reviewed
Hashisaka, M., Hiyama, N., Akiho, T., Muraki, K., Fujisawa, T.
Nature Physics 13 ( 6 ) 559 - 562 2017
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Brasseur, P., Tu, N. H., Sekine, Y., Muraki, K., Hashisaka, M., Fujisawa, T., Kumada, N.
Physical Review B 96 ( 8 ) 2017
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Long-lived binary tunneling spectrum in the quantum Hall Tomonaga-Luttinger liquid Reviewed
Washio, K., Nakazawa, R., Hashisaka, M., Muraki, K., Tokura, Y., Fujisawa, T.
Physical Review B 93 ( 7 ) 2016
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Rabi splitting in a two-electron double quantum dot induced by a surface acoustic wave
Fujisawa T., Sato Y., Chen J. C. H., Hashisaka M., Muraki K.
Meeting Abstracts of the Physical Society of Japan 71 1156 - 1156 2016
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22pAG-2 Non-Equilibrium Energy Spectrum in Copropagating Quantum Hall Edge Channels
Nakazawa R., Itoh K., Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 71 1422 - 1422 2016
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Energy relaxation processes in a quantum Hall edge channel investigated by hot-electron spectroscopy
Ota Tomoaki, Hashisaka Masayuki, Muraki Koji, Fujisawa Toshimasa
Meeting Abstracts of the Physical Society of Japan 71 1032 - 1032 2016
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Spatially separated charge and spin wave packets in copropagating quantum Hall edge channels
Hashisaka Masayuki, Hiyama Naoaki, Akiho Takafumi, Muraki Koji, Fujisawa Toshimasa
Meeting Abstracts of the Physical Society of Japan 71 1033 - 1033 2016
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19aAE-9 Magnetic field and temperature dependences of fractional quasiparticle creation in a local fractional quantum Hall region
Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1135 - 1135 2015
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22pBB-3 Controlling Electronic States in GaAs Quantum Dots with Surface Acoustic Wave Phonons
Fujisawa Toshimasa
Meeting Abstracts of the Physical Society of Japan 70 1336 - 1337 2015
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21pBK-10 Detection of inelastic processes in a quantum Hall edge channel using cross-correlation noise measurements
Ota T., Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1290 - 1290 2015
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Exchange-Induced Spin Blockade in a Two-Electron Double Quantum Dot
Imanaka, D., Sharmin, S., Hashisaka, M., Muraki, K., Fujisawa, T.
Physical Review Letters 115 ( 17 ) 2015
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21pBK-11 Heat-transport measurement between quantum Hall edge channels using a quantum-dot local thermometer
Nakazawa R., Morita K., Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1291 - 1291 2015
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23pBK-6 Electron Spin Transport through a Double Quantum Dot in a Surface Acoustic Cavity
Sato Y., Chen Jason C. H., Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1373 - 1373 2015
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21pBK-8 An edge-magnetoplasmon Mach-Zehnder interferometer
Hiyama N., Hashisaka M., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1288 - 1288 2015
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23pBK-3 Effect of nuclear spin polarization on singlet spin blockade in two electron double quantum dots
Imanaka D., Sharmin Sonia, Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1370 - 1370 2015
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Enhanced electron-phonon coupling for a semiconductor charge qubit in a surface phonon cavity Reviewed
Chen, J. C. H., Sato, Y., Kosaka, R., Hashisaka, M., Muraki, K., Fujisawa, T.
Scientific Reports 5 2015
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Shot-Noise Evidence of Fractional Quasiparticle Creation in a Local Fractional Quantum Hall State Reviewed
Hashisaka, Masayuki, Ota, Tomoaki, Muraki, Koji, Fujisawa, Toshimasa
Physical Review Letters 114 ( 5 ) 2015
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An edge-magnetoplasmon Mach-Zehnder interferometer Reviewed
Hiyama, N., Hashisaka, M., Fujisawa, T.
Applied Physics Letters 107 ( 14 ) 2015
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19aAE-10 Metastable non-equilibrium states in an artificial Tomonaga-Luttinger liquid formed in quantum Hall edge channels
Fujisawa T., Washio K., Nakazawa R., Hashisaka M., Muraki K., Tokura Y.
Meeting Abstracts of the Physical Society of Japan 70 1136 - 1136 2015
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23pBK-5 Surface-acoustic-wave stimulated phonon assist tunneling in a double quantum dot in a SAW cavity
Chen J. C. H., Sato Y., Hashisaka M., Muraki K., Fujisawa T.
Meeting Abstracts of the Physical Society of Japan 70 1372 - 1372 2015
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Single-electron counting statistics with a finite frequency bandwidth Reviewed
Watase, Narii, Hashisaka, Masayuki, Muraki, Koji, Fujisawa, Toshimasa
Japanese Journal of Applied Physics 53 ( 4 ) 2014
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Plasmon transport and its guiding in graphene Reviewed
Kumada, N., Dubourget, R., Sasaki, K., Tanabe, S., Hibino, H., Kamata, H., Hashisaka, M., Muraki, K., Fujisawa, T.
New Journal of Physics 16 ( 6 ) 063055 2014
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Time-resolved charge fractionalization in inhomogeneous Luttinger liquids Reviewed
Perfetto, E., Stefanucci, G., Kamata, H., Fujisawa, T.
Physical Review B 89 ( 20 ) 201413 2014
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Fractionalized wave packets from an artificial Tomonaga-Luttinger liquid Reviewed
Kamata, H., Kumada, N., Hashisaka, M., Muraki, K., Fujisawa, T.
Nature Nanotechnology 9 ( 3 ) 177 - 181 2014
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Cross-correlation measurement of quantum shot noise using homemade transimpedance amplifiers Reviewed
Hashisaka, Masayuki, Ota, Tomoaki, Yamagishi, Masakazu, Fujisawa, Toshimasa, Muraki, Koji
Review of Scientific Instruments 85 ( 5 ) 2014
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Spin-dependent tunneling rates for electrostatically defined GaAs quantum dots Reviewed
Yamagishi, M., Watase, N., Hashisaka, M., Muraki, K., Fujisawa, T.
Physical Review B 90 ( 3 ) 2014
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Stable and unstable dynamics of Overhauser fields in a double quantum dot Reviewed
Sharmin, Sonia, Muraki, Koji, Fujisawa, Toshimasa
Physical Review B 89 ( 11 ) 2014
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Distributed-element circuit model of edge magnetoplasmon transport Reviewed
Hashisaka, M., Kamata, H., Kumada, N., Washio, K., Murata, R., Muraki, K., Fujisawa, T.
Physical Review B 88 ( 23 ) 235409 2013
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Transient Current in the Spin Blockade Region of a Double Quantum Dot Reviewed
Sharmin, S., Muraki, K., Fujisawa, T.
Japanese Journal of Applied Physics 52 ( 11 ) 2013
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Plasmon transport in graphene investigated by time-resolved electrical measurements Reviewed
Kumada, N., Tanabe, S., Hibino, H., Kamata, H., Hashisaka, M., Muraki, K., Fujisawa, T.
Nature Communications 4 6 - 6 2013
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Hashisaka, M., Washio, K., Kamata, H., Muraki, K., Fujisawa, T.
Physical Review B 85 ( 15 ) 155424 2012
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Magnetic-Field Dependence of Tunnel Couplings in Carbon Nanotube Quantum Dots
Grove-Rasmussen, K., Grap, S., Paaske, J., Flensberg, K., Andergassen, S., Meden, V., Jorgensen, H. I., Muraki, K., Fujisawa, T.
Physical Review Letters 108 ( 17 ) 2012
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Correlation of 1/f Noise between Semiconductor Point Contacts with a Common Lead Reviewed
Yamagishi, M., Hashisaka, M., Muraki, K., Fujisawa, T.
Japanese Journal of Applied Physics 51 ( 2 ) 2012
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Frequency conversion of radio-frequency edge magnetoplasmons using a quantum point contact Reviewed
Hashisaka, M., Murata, R., Muraki, K., Fujisawa, T.
Applied Physics Letters 100 ( 23 ) 2012
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Impact of Valley Polarization on the Resistivity in Two Dimensions
Takashina, K., Niida, Y., Renard, V. T., Fujiwara, A., Fujisawa, T., Muraki, K., Hirayama, Y.
Physical Review Letters 106 ( 19 ) 2011
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Multiple two-qubit operations for a coupled semiconductor charge qubit
Fujisawa, T., Shinkai, G., Hayashi, T., Ota, T.
Physica E-Low-Dimensional Systems & Nanostructures 43 ( 3 ) 2011
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Gate-Dependent Orbital Magnetic Moments in Carbon Nanotubes
Jespersen, T. S., Grove-Rasmussen, K., Flensberg, K., Paaske, J., Muraki, K., Fujisawa, T., Nygard, J.
Physical Review Letters 107 ( 18 ) 2011
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Gate-dependent spin-orbit coupling in multielectron carbon nanotubes
Jespersen, T. S., Grove-Rasmussen, K., Paaske, J., Muraki, K., Fujisawa, T., Nygard, J., Flensberg, K.
Nature Physics 7 ( 4 ) 2011
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Time Resolved Potential Measurement At Quantum Point Contacts Under Irradiation Of Surface Acoustic Burst Wave
Fujisawa, T., Nishio, K., Nagase, T., Hashisaka, M., Muraki, K.
Physics of Semiconductors: 30th International Conference on the Physics of Semiconductors 1399 2011
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Field and Density Dependence of Edge Magnetoplasmon Transport in a Quantum Hall System Reviewed
Kumada, N., Kamata, H., Muraki, K., Fujisawa, T.
Horiba International Conference: the 19th International Conference on the Application of High Magnetic Fields in Semiconductor Physics and Nanotechnology 334 012032 2011
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Edge magnetoplasmon transport in gated and ungated quantum Hall systems Reviewed
Kumada, N., Kamata, H., Fujisawa, T.
Physical Review B 84 ( 4 ) 045314 2011
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Admittance Measurement for a Quantum Point Contact in Multiterminal Quantum Hall Device Reviewed
Washio, K., Hashisaka, M., Kamata, H., Muraki, K., Fujisawa, T.
Japanese Journal of Applied Physics 50 ( 4 ) 04DJ04 - 04DJ04-4 2011
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Interferometric detection of edge magnetoplasmons in AlGaAs/GaAs heterostructures Reviewed
Hashisaka, Masayuki, Washio, Kazuhisa, Kamata, Hiroshi, Muraki, Koji, Fujisawa, Toshimasa
Physica Status Solidi C: Current Topics in Solid State Physics, Vol 8, No 2 8 ( 2 ) 381 - 383 2011
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Kondo Effect in a Semiconductor Quantum Dot with a Spin-Accumulated Lead
Kobayashi, T., Tsuruta, S., Sasaki, S., Fujisawa, T., Tokura, Y., Akazaki, T.
Physical Review Letters 104 ( 3 ) 2010
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Wide-band capacitance measurement on a semiconductor double quantum dot for studying tunneling dynamics Reviewed
Ota, T., Hayashi, T., Muraki, K., Fujisawa, T.
Applied Physics Letters 96 ( 3 ) 2010
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Bidirectional single-electron counting and the fluctuation theorem
Utsumi, Y., Golubev, D. S., Marthaler, M., Saito, K., Fujisawa, T., Schon, G.
Physical Review B 81 ( 12 ) 2010
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Voltage-controlled group velocity of edge magnetoplasmon in the quantum Hall regime Reviewed
Kamata, H., Ota, T., Muraki, K., Fujisawa, T.
Physical Review B 81 ( 8 ) 085329 2010
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Separately contacted monocrystalline silicon double-layer structure with an amorphous silicon dioxide barrier made by wafer bonding
Takashina, K., Nagase, M., Nishiguchi, K., Ono, Y., Omi, H., Fujiwara, A., Fujisawa, T., Muraki, K.
Semiconductor Science and Technology 25 ( 12 ) 2010
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Intrinsic Gap and Exciton Condensation in the v(T)=1 Bilayer System
Giudici, P., Muraki, K., Kumada, N., Fujisawa, T.
Physical Review Letters 104 ( 5 ) 2010
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Time-Dependent Local Potential Induced by Scanning Gate Microscopy
Wang, Z. Z., Chen, D. M., Ota, T., Fujisawa, T.
Japanese Journal of Applied Physics 48 ( 4 ) 04C148 - 04C148-4 2009
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Spin splitting of upper electron subbands in a SiO2/Si(100)/SiO2 quantum well with in-plane magnetic field
Niida, Y., Takashina, K., Fujiwara, A., Fujisawa, T., Hirayama, Y.
Applied Physics Letters 94 ( 14 ) 2009
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NEGATIVE MAGNETORESISTANCE OF A SILICON 2DEG UNDER IN-PLANE MAGNETIC FIELD DUE TO SPIN-SPLITTING OF UPPER SUBBANDS
Takashina, K., Niida, Y., Renard, V. T., Fujiwara, A., Fujisawa, T., Hirayama, Y.
International Journal of Modern Physics B 23 ( 12-13 ) 2009
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Nuclear Spin Resonance Induced by Radio Frequency Electric Field
Kumada, N., Kamada, T., Hirayama, Y., Miyashita, S., Fujisawa, T.
Physics of Semiconductors 1199 2009
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Correlation Measurement of Time-Dependent Potentials in a Semiconductor Quantum Point Contact Reviewed
Kamata, H., Ota, T., Fujisawa, T.
Japanese Journal of Applied Physics 48 ( 4 ) 04C149 - 04C149-4 2009
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Electrons and holes in a 40 nm thick silicon slab at cryogenic temperatures
Takashina, K., Nishiguchi, K., Ono, Y., Fujiwara, A., Fujisawa, T., Hirayama, Y., Muraki, K.
Applied Physics Letters 94 ( 14 ) 142104 - 142104 2009
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Fano-Kondo Interplay in a Side-Coupled Double Quantum Dot
Sasaki, S., Tamura, H., Akazaki, T., Fujisawa, T.
Physical Review Letters 103 ( 26 ) 2009
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Bidirectional Current Drag Induced by Two-Electron Cotunneling in Coupled Double Quantum Dots Reviewed
Shinkai, G., Hayashi, T., Ota, T., Muraki, K., Fujisawa, T.
Applied Physics Express 2 ( 8 ) 2009
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Correlated Coherent Oscillations in Coupled Semiconductor Charge Qubits
Shinkai, G., Hayashi, T., Ota, T., Fujisawa, T.
Physical Review Letters 103 ( 5 ) 2009
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A gate-defined silicon quantum dot molecule Reviewed
Liu, H. W., Fujisawa, T., Inokawa, H., Ono, Y., Fujiwara, A., Hirayama, Y.
Applied Physics Letters 92 ( 22 ) 2008
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Spin-conserved single-electron transport between Zeeman sublevels in a few-electron quantum dot Reviewed
Fujisawa, T., Shinkai, G., Hayashi, T.
Japanese Journal of Applied Physics 47 ( 4 ) 3107 - 3110 2008
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Ota, T., Kumada, N., Yusa, G., Miyashita, S., Fujisawa, T., Hirayama, Y.
Japanese Journal of Applied Physics 47 ( 4 ) 3115 - 3117 2008
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Initialization and logic gate operations of nuclear spin qubits using a submicron scale resistively-detected NMR device Reviewed
T. Ota, G. Yusa, N. Kumada, S. Miyashita, T. Fujisawa, Y. Hirayama
Physica Status Solidi (C) Current Topics in Solid State Physics 5 ( 1 ) 306 - 309 2008
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Voltage-pulse-induced electromigration
Hayashi, T., Fujisawa, T.
Nanotechnology 19 ( 14 ) 2008
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Spatial imaging of valence band electronic structures in a GaSb/InAs quantum well
Suzuki, K., Kanisawa, K., Perraud, S., Fujisawa, T.
Applied Surface Science 254 ( 23 ) 2008
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Spin-dependent phase diagram of the nu(T)=1 bilayer electron system
Giudici, P., Muraki, K., Kumada, N., Hirayama, Y., Fujisawa, T.
Physical Review Letters 100 ( 10 ) 2008
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Observation of Bogoliubov excitations in exciton-polariton condensates
Utsunomiya, S., Tian, L., Roumpos, G., Lai, C. W., Kumada, N., Fujisawa, T., Kuwata-Gonokami, M., Loffler, A., Hofling, S., Forchel, A., Yamamoto, Y.
Nature Physics 4 ( 9 ) 700 - 705 2008
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Pauli-spin-blockade transport through a silicon double quantum dot
Liu, H. W., Fujisawa, T., Ono, Y., Inokawa, H., Fujiwara, A., Takashina, K., Hirayama, Y.
Physical Review B 77 ( 7 ) 2008
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A triple quantum dot in a single-wall carbon nanotube
Grove-Rasmussen, K., Jorgensen, H. I., Hayashi, T., Lindelof, P. E., Fujisawa, T.
Nano Letters 8 ( 4 ) 2008
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Bound states induced by a single donor in a semiconductor quantum well: A scanning tunneling spectroscopy study
Perraud, S., Kanisawa, K., Wang, Z. Z., Fujisawa, T.
Physica E-Low-Dimensional Systems & Nanostructures 40 ( 5 ) 2008
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GaAs microcavity exciton-polaritons in a trap
Kim, N. Y., Lai, C. W., Utsunomiya, S., Roumpos, G., Fraser, M., Deng, H., Byrnes, T., Recher, P., Kumada, N., Fujisawa, T., Yamamoto, Y.
Physica Status Solidi B-Basic Solid State Physics 245 ( 6 ) 2008
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Many-body excitations in the tunneling current spectra of a few-electron quantum dot
Melnikov, D. V., Fujisawa, T., Austing, D. G., Tarucha, S., Leburton, J. P.
Physical Review B 77 ( 16 ) 2008
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Direct measurement of the binding energy and bohr radius of a single hydrogenic defect in a semiconductor quantum well
Perraud, S., Kanisawa, K., Wang, Z. Z., Fujisawa, T.
Physical Review Letters 100 ( 5 ) 2008
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Electric field induced nuclear spin resonance mediated by oscillating electron spin domains in GaAs-based semiconductors
Kumada, N., Kamada, T., Miyashita, S., Hirayama, Y., Fujisawa, T.
Physical Review Letters 101 ( 13 ) 2008
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Controlled resonant tunneling in a coupled double-quantum-dot system Reviewed
Shinkai, G., Hayashi, T., Hirayama, Y., Fujisawa, T.
Applied Physics Letters 90 ( 10 ) 2007
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Higher-order moment of single-electron current noise in a double quantum dot
Fujisawa, T., Hayashi, T., Hirayama, Y.
Physics of Semiconductors, Pts A and B 893 2007
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Imaging the percolation of localized states in a multisubband two-dimensional electronic system subject to a disorder potential
Perraud, S., Kanisawa, K., Wang, Z. Z., Fujisawa, T.
Physical Review B 76 ( 19 ) 2007
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Coherent zero-state and p-state in an exciton-polariton condensate array
Lai, C. W., Kim, N. Y., Utsunomiya, S., Roumpos, G., Deng, H., Fraser, M. D., Byrnes, T., Recher, P., Kumada, N., Fujisawa, T., Yamamoto, Y.
Nature 450 ( 7169 ) 2007
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Decoherence of nuclear spins due to dipole-dipole interactions probed by resistively detected nuclear magnetic resonance
Ota, T., Yusa, G., Kumada, N., Miyashita, S., Fujisawa, T., Hirayama, Y.
Applied Physics Letters 91 ( 19 ) 2007
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Zeeman splitting in single-electron transport through a few-electron quantum dot
Fujisawa, T., Shinkai, G., Hayashi, T.
Physical Review B 76 ( 4 ) 2007
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Interaction of a 2-level system with 2D phonons
Naber, W. J. M., Fujisawa, T., Liu, H. W., van der Wiel, W. G.
Physics of Semiconductors, Pts A and B 893 2007
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Spatial imaging of two-dimensional electronic states in semiconductor quantum wells
Suzuki, K., Kanisawa, K., Janer, C., Perraud, S., Takashina, K., Fujisawa, T., Hirayama, Y.
Physical Review Letters 98 ( 13 ) 2007
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Real-time observation of charge states and energy relaxation in a double quantum dot Reviewed
Hayashi, T., Fujisawa, T., Tomita, R., Hirayama, Y.
Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers 45 ( 4B ) 3629 - 3632 2006
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Surface-acoustic-wave-induced transport in a double quantum dot
Naber, W. J. M., Fujisawa, T., Liu, H. W., van der Wiel, W. G.
Physical Review Letters 96 ( 13 ) 2006
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Time-dependent single-electron transport through quantum dots
Fujisawa, T., Hayashi, T., Sasaki, S.
Reports on Progress in Physics 69 ( 3 ) 2006
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Bidirectional counting of single electrons
Fujisawa, T., Hayashi, T., Tomita, R., Hirayama, Y.
Science 312 ( 5780 ) 2006
-
Pauli blockade transport in the cotunneling regime through a double quantum dot
Liu, H. W., Fujisawa, T., Hayashi, T., Hirayama, Y.
Physica Status Solidi C - Current Topics in Solid State Physics, Vol 3, No 11 3 2006
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Electrical pump-and-probe study of spin singlet-triplet relaxation in a quantum dot
Sasaki, S., Fujisawa, T., Hayashi, T., Hirayama, Y.
Physical Review Letters 95 ( 5 ) 2005
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Pauli spin blockade in cotunneling transport through a double quantum dot
Liu, H. W., Fujisawa, T., Hayashi, T., Hirayama, Y.
Physical Review B 72 ( 16 ) 2005
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High-frequency manipulation of few-electron double quantum dots - toward spin qubits
Kodera, T., van der Wiel, W. G., Ono, K., Sasaki, S., Fujisawa, T., Tarucha, S.
Physica E-Low-Dimensional Systems & Nanostructures 22 ( 1-3 ) 2004
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Controlled decoherence of a charge qubit in a double quantum dot
Fujisawa, T., Hayashi, T., Hirayama, Y.
Journal of Vacuum Science & Technology B 22 ( 4 ) 2004
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Electron counting of single-electron tunneling current
Fujisawa, T., Hayashi, T., Hirayama, Y., Cheong, H. D., Jeong, Y. H.
Applied Physics Letters 84 ( 13 ) 2004
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Background charge fluctuation in a GaAs quantum dot device
Jung, S. W., Fujisawa, T., Hirayama, Y., Jeong, Y. H.
Applied Physics Letters 85 ( 5 ) 2004
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Coherent charge oscillation in a semiconductor double quantum dot
Hayashi, T., Fujisawa, T., Cheong, H. D., Jeong, Y. H., Hirayama, Y.
Ieee Transactions on Nanotechnology 3 ( 2 ) 2004
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Rotation and phase-shift operations for a charge qubit in a double quantum dot
Fujisawa, T., Hayashi, T., Cheong, H. D., Jeong, Y. H., Hirayama, Y.
Physica E-Low-Dimensional Systems & Nanostructures 21 ( 2-4 ) 2004
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Electrical pulse measurement, inelastic relaxation, and non-equilibrium transport in a quantum dot
Fujisawa, T., Austing, D. G., Tokura, Y., Hirayama, Y., Tarucha, S.
Journal of Physics-Condensed Matter 15 ( 33 ) 2003
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Electrical pump and probe measurements of a quantum dot in the coulomb blockade regime
Fujisawa, T., Austing, D. G., Hirayama, Y., Tarucha, S.
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 42 ( 7B ) 4804 - 4808 2003
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Investigation of spin state in a quantum dot by using strongly asymmetric tunnel barriers
Hayashi, T., Fujisawa, T., Hirayama, Y.
Physica Status Solidi B-Basic Solid State Physics 238 ( 2 ) 2003
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Spin selection rules in single-electron transport through a few-electron quantum dot
Fujisawa, T., Austing, D. G., Tokura, Y., Hirayama, Y., Tarucha, S.
Physics of Semiconductors 2002, Proceedings 171 2003
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Electromagnetic Aharonov-Bohm effect in a two-dimensional electron gas ring
van der Wiel, W. G., Nazarov, Y. V., De Franceschi, S., Fujisawa, T., Elzerman, J. M., Huizeling, Ewgm, Tarucha, S., Kouwenhoven, L. P.
Physical Review B 67 ( 3 ) 2003
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Electron transport through double quantum dots
van der Wiel, W. G., De Franceschi, S., Elzerman, J. M., Fujisawa, T., Tarucha, S., Kouwenhoven, L. P.
Reviews of Modern Physics 75 ( 1 ) 2003
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Coherent manipulation of electronic states in a double quantum dot
Hayashi, T., Fujisawa, T., Cheong, H. D., Jeong, Y. H., Hirayama, Y.
Physical Review Letters 91 ( 22 ) 2003
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Out-of-equilibrium Kondo effect in a mesoscopic device
De Franceschi, S., Hanson, R., van der Wiel, W. G., Elzerman, J. M., Wijpkema, J. J., Fujisawa, T., Tarucha, S., Kouwenhoven, L. P.
Physical Review Letters 89 ( 15 ) 2002
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Spin-dependent energy relaxation inside a quantum dot
Fujisawa, T., Tokura, Y., Austing, D. G., Hirayama, Y., Tarucha, S.
Physica B-Condensed Matter 314 ( 1-4 ) 2002
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Impedance analysis of a radio-frequency single-electron transistor
Cheong, H. D., Fujisawa, T., Hayashi, T., Hirayama, Y., Jeong, Y. H.
Applied Physics Letters 81 ( 17 ) 2002
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Nonequilibrium transport through a vertical quantum dot in the absence of spin-flip energy relaxation
Fujisawa, T., Austing, D. G., Tokura, Y., Hirayama, Y., Tarucha, S.
Physical Review Letters 88 ( 23 ) 2002
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Allowed and forbidden transitions in artificial hydrogen and helium atoms
Fujisawa, T., Austing, D. G., Tokura, Y., Hirayama, Y., Tarucha, S.
Nature 419 ( 6904 ) 2002
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Temporal and spatial characterization of quantum dots
Hirayama, Y., Kanisawa, K., Tokura, Y., Yamaguchi, H., Fujisawa, T.
2001
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Novel Kondo anomaly in quantum dots
Tarucha, S., Austing, D. G., Sasaki, S., Fujisawa, T., Tokura, Y., Elzerman, J. M., van der Wiel, W., de Franseschi, S., Kouwenhoven, L. P.
Materials Science and Engineering B-Solid State Materials for Advanced Technology 84 ( 1-2 ) 2001
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Transient current spectroscopy of a quantum dot in the Coulomb blockade regime
Fujisawa, T., Tokura, Y., Hirayama, Y.
Physical Review B 63 ( 8 ) 2001
-
Relaxation time of excited states in a quantum dot studied by pulse-excited current
Fujisawa, T., Tokura, Y., Hirayama, Y.
Proceedings of the 25th International Conference on the Physics of Semiconductors, Pts I and Ii 87 2001
-
Multi-level Kondo regimes in a quantum dot
De Franceschi, S., Van Der Wiel, W. G., Fujisawa, T., Elzerman, J. M., Izumida, W., Tarucha, S., Kouwenhoven, L. P.
2001
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Energy relaxation process in a quantum dot studied by DC current and pulse-excited current measurements Reviewed
Fujisawa, T., Tokura, Y., Hirayama, Y.
Physica B 298 ( 1-4 ) 573 - 579 2001
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A double quantum dot as an artificial two-level system
van der Wiel, W. G., Fujisawa, T., Tarucha, S., Kouwenhoven, L. P.
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 40 ( 3B ) 2100 - 2104 2001
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From quantum effects to quantum circuits - Toward the quantum computer
Takayanagi, H., Ando, H., Fujisawa, T.
Ntt Review 12 ( 1 ) 2000
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Transmission type RF single electron transistor operation of a semiconductor quantum dot
Fujisawa, T., Hirayama, Y.
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 39 ( 4B ) 2338 - 2340 2000
-
Inelastic tunneling in a double quantum dot coupled to a bosonic environment
Fujisawa, T., van der Wiel, W. G., Kouwenhoven, L. P.
Physica E 7 ( 3-4 ) 2000
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The Kondo effect in the unitary limit
van der Wiel, W. G., De Franceschi, S., Fujisawa, T., Elzerman, J. M., Tarucha, S., Kouwenhoven, L. P.
Science 289 ( 5487 ) 2000
-
Charge noise analysis of an AlGaAs/GaAs quantum dot using transmission-type radio-frequency single-electron transistor technique
Fujisawa, T., Hirayama, Y.
Applied Physics Letters 77 ( 4 ) 2000
-
Elastic and inelastic single electron tunneling in coupled two dot system
Tarucha, S., Fujisawa, T., Ono, K., Austing, D. G., Oosterkamp, T. H., van der Wiel, W. G., Kouwenhoven, L. P.
Microelectronic Engineering 47 ( 1-4 ) 1999
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Microwave spectroscopy of a double quantum dot in the low- and high-power regime
van der Wiel, W. G., Fujisawa, T., Oosterkamp, T. H., Kouwenhoven, L. P.
Physica B 272 ( 1-4 ) 1999
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Photon assisted tunneling spectroscopy on a double quantum dot
Fujisawa, T., Oosterkamp, T. H., van der Wiel, W. G., Tarucha, S., Kouwenhoven, L. P.
Compound Semiconductors 1998 1999
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Spontaneous emission spectrum in double quantum dot devices
Fujisawa, T., Oosterkamp, T. H., van der Wiel, W. G., Broer, B. W., Aguado, R., Tarucha, S., Kouwenhoven, L. P.
Science 282 ( 5390 ) 1998
-
Microwave spectroscopy of a quantum-dot molecule
Oosterkamp, T. H., Fujisawa, T., van der Wiel, W. G., Ishibashi, K., Hijman, R. V., Tarucha, S., Kouwenhoven, L. P.
Nature 395 ( 6705 ) 873 - 876 1998
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Photon assisted tunnelling in single and coupled quantum dot systems
Fujisawa, T., Tarucha, S.
Superlattices and Microstructures 21 ( 2 ) 1997
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Multiple photon assisted tunneling between two coupled quantum dots
Fujisawa, T., Tarucha, S.
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 36 ( 6B ) 4000 - 4003 1997
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Tunnelling and transfer between 1D and 2D electrons in adjusted quantum wells with thin barrier
Friedland, K. J., Hirayama, Y., Fujisawa, T., Saku, T., Tarucha, S.
Physica B 227 ( 1-4 ) 1996
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Resonant tunneling properties of single electron transistors with a novel double-gate geometry
Fujisawa, T., Tarucha, S.
Applied Physics Letters 68 ( 4 ) 1996
-
ALGAAS/INGAAS/GAAS SINGLE-ELECTRON TRANSISTORS FABRICATED BY GA FOCUSED ION-BEAM IMPLANTATION
Fujisawa, T., Hirayama, Y., Tarucha, S.
Applied Physics Letters 64 ( 17 ) 1994
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NANOSTRUCTURE FABRICATION AND THE SCIENCE USING FOCUSED ION-BEAMS
Fujisawa, T., Bever, T., Hirayama, Y., Tarucha, S.
Journal of Vacuum Science & Technology B 12 ( 6 ) 1994
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Itoh, M., Saku, T., Fujisawa, T., Hirayama, Y., Tarucha, S.
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 33 ( 1B ) 771 - 774 1994
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SUB-MU-M WIDE CHANNELS WITH SURFACE-POTENTIAL COMPENSATED BY FOCUSED SI ION-BEAM IMPLANTATION
Fujisawa, T., Saku, T., Hirayama, Y., Tarucha, S.
Applied Physics Letters 63 ( 1 ) 1993
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THE LOCAL-ENVIRONMENT-DEPENDENT DX CENTERS
Mizuta, M., Baba, T., Fujisawa, T., Yoshino, J., Kukimoto, H.
Institute of Physics Conference Series ( 106 ) 1990
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DIRECT EVIDENCE FOR THE NEGATIVE-U PROPERTY OF THE DX-CENTER AS STUDIED BY HYDROSTATIC-PRESSURE EXPERIMENTS ON GAAS SIMULTANEOUSLY DOPED WITH GE AND SI
Fujisawa, T., Yoshino, J., Kukimoto, H.
Japanese Journal of Applied Physics Part 2-Letters 29 ( 3 ) L388 - L390 1990
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EFFECT OF LOCAL ATOMIC CONFIGURATION ON DX ENERGY-LEVEL
Baba, T., Mizuta, M., Fujisawa, T., Yoshino, J., Kukimoto, H.
Impurities, Defects and Diffusion in Semiconductors : Bulk and Layered Structures 163 1990
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THE NEGATIVE-U PROPERTY OF THE DX CENTER EVIDENCED BY HYDROSTATIC-PRESSURE EXPERIMENTS
Fujisawa, T., Yoshino, J., Kukimoto, H.
1990
-
THE LOCAL-ENVIRONMENT-DEPENDENT DX CENTERS
Mizuta, M., Baba, T., Fujisawa, T., Yoshino, J., Kukimoto, H.
106 1990
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COMPOSITION AND PRESSURE DEPENDENCES OF DX-CENTER IN ALGASB
Takeda, Y., Fujisawa, T., Zhu, Y., Sasaki, A., Kukimoto, H.
1989
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DX CENTERS IN III-V-COMPOUND AND ALLOY SEMICONDUCTORS AS STUDIED BY HYDROSTATIC-PRESSURE EXPERIMENTS
Fujisawa, T., Yoshino, J., Kukimoto, H.
Journal of Crystal Growth 98 ( 1-2 ) 243 - 248 1989
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THE LOCAL-ENVIRONMENT-DEPENDENT DX CENTERS - EVIDENCE FOR THE SINGLE ENERGY-LEVEL WITH A SPECIFIED CONFIGURATION
Baba, T., Mizuta, M., Fujisawa, T., Yoshino, J., Kukimoto, H.
Japanese Journal of Applied Physics Part 2-Letters 28 ( 6 ) L891 - L894 1989
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COMPOSITION AND PRESSURE DEPENDENCES OF DX-CENTER IN ALGASB
Takeda, Y., Fujisawa, T., Zhu, Y., Sasaki, A., Kukimoto, H.
Institute of Physics Conference Series <D> ( 96 ) 1989
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METASTABLE BEHAVIOR OF THE DX CENTER IN SI-DOPED GAAS
Fujisawa, T., Kristofik, J., Yoshino, J., Kukimoto, H.
Japanese Journal of Applied Physics Part 2-Letters 27 ( 12 ) 1988
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OBSERVATION OF THE PERSISTENT PHOTOCONDUCTIVITY DUE TO THE DX CENTER IN GAAS UNDER HYDROSTATIC-PRESSURE
Tachikawa, M., Fujisawa, T., Kukimoto, H., Shibata, A., Oomi, G., Minomura, S.
Japanese Journal of Applied Physics Part 2-Letters 24 ( 11 ) L893 - L894 1985
MISC
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Plasmon assisted tunneling in a double quantum dot coupled to a quantum-Hall plasmon resonator
LIN Chaojing, LIN Chaojing, 二俣晃, 橋坂昌幸, 秋保貴史, 村木康二, 藤澤利正
日本物理学会講演概要集(CD-ROM) 78 ( 1 ) 2023
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Time-resolved investigation of plasmon mode along interface channels in integer and fractional quantum Hall regimes
Chaojing Lin, Masayuki Hashisaka, Takafumi Akiho, Koji Muraki, Toshimasa Fujisawa
PHYSICAL REVIEW B 104 ( 12 ) 2021.9
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Fractionalization of charge wave packets at integer/fractional quantum Hall Y junctions
LIN Chaojing, 橋坂昌幸, 秋保貴史, 村木康二, 藤澤利正
日本物理学会講演概要集(CD-ROM) 75 ( 2 ) 2020
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Tomonaga–Luttinger-liquid nature of edge excitations in integer quantum Hall edge channels
Masayuki Hashisaka, Toshimasa Fujisawa
Reviews in Physics 3 32 - 43 2018.11
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7pAV-7 Cross-correlation measurement of repartitioned noise in a quantum Hall edge channel
Ota T., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 69 ( 2 ) 472 - 472 2014.8
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7pAV-8 Energy transport between counter-propagating quantum Hall edge channels
Nakazawa R., Washio K., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 69 ( 2 ) 472 - 472 2014.8
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7pAV-6 Fractional quasiparticle creation at a local fractional quantum Hall state
Hashisaka M., Ota T., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 69 ( 2 ) 472 - 472 2014.8
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Charge-density-wave dynamics in quantum Hall edge states Reviewed
Masayuki Hashisaka, Hiroshi Kamata, Toshimasa Fujisawa, Norio Kumada, Koji Muraki
SOLID STATE PHYSICS 49 ( 5 ) 359 2014.5
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28aAU-10 Capacitance probing of charge/spin dynamics in a few-electron double quantum dot
Ota T., Hitachi K., Fujisawa T., Muraki K.
Meeting abstracts of the Physical Society of Japan 69 ( 1 ) 702 - 702 2014.3
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28aAU-1 Single-electron counting statistics with a finite frequency bandwidth
Watase N., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 69 ( 1 ) 700 - 700 2014.3
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28aAU-8 Time-resolved measurements of surface acoustic waves with quantum point contacts
Chen J. C. H., Kosaka R., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 69 ( 1 ) 701 - 701 2014.3
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Shot noise of fractional quasiparticles at local fractional quantum Hall states
Hahisaka M., Ota T., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 2 ) 612 - 612 2013.8
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Positive cross-correlation of redistributed shot noise in quantum Hall edge channels
Ota T., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 2 ) 610 - 610 2013.8
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Measurement of Localized Temperature in Quantum Hall Edge Channel Using a Time Resolved Tunnel Spectroscopy
Washio K., Hashisaka M., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 2 ) 623 - 623 2013.8
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Fractionallized Wave Packets from an Artificial Tomonaga-Luttinger Liquid
Kamata H., Kumada N., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 2 ) 610 - 610 2013.8
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28pPSA-7 Resolution of Time Resolved Tunnel Spectroscopy Using a Quantum Dot
Washio K., Hashisaka M., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 1 ) 777 - 777 2013.3
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28pXQ-8 Counting spin-polarized electron tunneling events through a quantum dot in a high magnetic field
Yamagishi M., Watase N., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 1 ) 775 - 775 2013.3
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28pXQ-3 Stability of electron-nuclear feedback in a double quantum dot
Fujisawa T., Sharmin Sonia, Muraki K.
Meeting abstracts of the Physical Society of Japan 68 ( 1 ) 774 - 774 2013.3
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28pXQ-4 Sharp dip structures in excited-state current spectrum of a double quantum dot
SHARMIN Sonia, MURAKI Koji, FUJISAWA Toshimasa
Meeting abstracts of the Physical Society of Japan 68 ( 1 ) 774 - 774 2013.3
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27aXQ-4 Resonance of Edge Magnetoplasmons in cavity structures
Hashisaka M., Kamata H., Kumada N., Washio K., Murata R., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 68 ( 1 ) 760 - 760 2013.3
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20pPSA-12 Effect of dynamic nuclear spin polarization on the transient current of a double quantum dot in the spin blockade region
SHARMIN Sonia, MURAKI Koji, FUJISAWA Toshimasa
Meeting abstracts of the Physical Society of Japan 67 ( 2 ) 646 - 646 2012.8
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18pFB-8 Time-resolved measurement of Coulomb drag in counter-propagating quantum Hall edge channels
Kamata H., Kumada N., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 2 ) 620 - 620 2012.8
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20aEC-8 Plasmon Transport in Graphene Investigated by Time-Resolved Measurement Using Nanoribbon
Kumada N., Tanabe S., Hibino H., Kamata H., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 2 ) 634 - 634 2012.8
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26pSA-10 Cross-Correlation Measurement for Shot Noise in a Quantum Point Contact Using a Homemade-Cryogenic-Current Amplifier
Yamagishi M., Hashisaka M., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 1 ) 750 - 750 2012.3
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25pCJ-7 Distributed electrochemical capacitance between quantum Hall edge states
Hashisaka M., Washio K., Kamata H., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 1 ) 736 - 736 2012.3
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26pCE-9 Energy and Time Resolved Measurement of Edge Magnetoplasmons Using a Quantum Dot
Washio K., Hashisaka M., Kamata H., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 1 ) 744 - 744 2012.3
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24aSB-8 Plasmon transport in graphene on SiC
Kumada N., Tanabe S., Hibino H., Kamata H., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 1 ) 721 - 721 2012.3
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25pCJ-6 Local filling factor dependence of edge magnetoplasmon excitations onder a gale electrode
Kamata H., Kumada N., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 67 ( 1 ) 736 - 736 2012.3
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21pPSA-5 Harmonic distortion due to the non-linear conductance in a Quantum Point Contact
Murata R., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 2 ) 671 - 671 2011.8
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23pTM-6 Surface acoustic wave cavity characterized by time resolved potential measurements
Mizuno S., Nishio K., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 2 ) 696 - 696 2011.8
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22aTL-4 Time-resolved transport measurement in graphene on SiC
Kumada N., Tanabe S., Hibino H., Kamata H., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 2 ) 675 - 675 2011.8
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28aHD-13 Time-resolved spectroscopy of surface acoustic wave associated with periodic metal structure on semiconductor surface
Fujisawa T., Mizuno S., Nishio K., Hashisaka M., Muraki K.
Meeting abstracts of the Physical Society of Japan 66 ( 1 ) 726 - 726 2011.3
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25pHG-11 Admittance of a Quantum Point Contact in the Quantum Hall Regime
Washio K., Hashisaka M., Kamata H., Murata R., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 1 ) 703 - 703 2011.3
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26aPS-93 Correlation Measurements of background charge fluctuation at quantum point contacts
Yamagishi M., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 1 ) 713 - 713 2011.3
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25pHG-10 Transmission spectra of coupled plasmonic cavities
Hashiaska M., Kumada N., Washio K., Kamata H., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 1 ) 703 - 703 2011.3
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25pHG-9 Measurement of edge magnetoplasmon transport for gate defined edge channels
Kamata H., Kumada N., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 66 ( 1 ) 702 - 702 2011.3
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24aXA-3 Voltage-controlled resonator for edge magnetoplasmons
Kamata H., Kumada N., Hashisaka H., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 65 ( 2 ) 648 - 648 2010.8
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24aXA-4 Field dependence of edge magnetoplasmon transport in quantum Hall systems
Kumada N., Kamata H., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 65 ( 2 ) 649 - 649 2010.8
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23pPSB-61 Measurement scheme for quantum noise in mesoscopic devices using a current amplifier
Hashisaka Masayuki, Fujisawa Toshimasa
Meeting abstracts of the Physical Society of Japan 65 ( 2 ) 643 - 643 2010.8
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20aHV-4 Time-resolved surface acoustic wave potential at quantum point contacts
Nishio K., Nagase T., Hashisaka M., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 65 ( 1 ) 697 - 697 2010.3
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21pHV-8 Microwave transport as the edge magnetoplasmon in quantum Hall edge state
Hashisaka M., Washio K., Kamata H., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 65 ( 1 ) 718 - 718 2010.3
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30pTX-4 Effects of coupling to the leads on level crossings in a carbon nanotube quantum dot
Grove-Rasmussen K., Jorgensen H. I., Lindelof P. E., Muraki K., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 64 ( 1 ) 713 - 713 2009.3
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27pVE-13 Photoluminescence and transport simultaneous measurements of two-dimensional electron systems
Hayakawa J., Kawamura T., Kuwano M., Onomitsu K., Fujisawa T., Yusa G.
Meeting abstracts of the Physical Society of Japan 64 ( 1 ) 688 - 688 2009.3
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28aTX-4 Time-resolved electron wavepacket transport in the quantum Hall regime
Kamata Hiroshi, Ota Takeshi, Muraki Koji, Fujisawa Toshimasa
Meeting abstracts of the Physical Society of Japan 64 ( 1 ) 696 - 696 2009.3
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単一電子輸送における揺らぎの定理
内海裕洋, GOLUBEV D., HETTLER M., MARHALER M., 齋藤圭司, 藤澤利正, 藤澤利正, SCHOEN G., SCHOEN G.
日本物理学会講演概要集 64 ( 2 ) 2009
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20pYF-9 High frequency capacitance measurements using a double-quantum dot
Ota T., Hayashi T., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 594 - 594 2008.8
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20pYK-9 Optical Measurement of Nuclear Spin Polarization at the Filling Factor v=2/3 Fractional Quantum Hall System
Hayakawa J., Kawamura T., Rossander Lea Hildebrandt, Kuwano M., Onomitsu K., Miyashita S., Fujisawa T., Yusa G.
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 598 - 598 2008.8
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20aYK-8 Confinement Potential Dependence of the Magnetoresistivity of a Two-Dimensional Hole System in a SiO_2/(100)Si/SiO_2 Quantum Well
Niida Y., Takashina K., Nishiguchi K., Ono Y., Fujiwara A., Hirayama Y., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 587 - 587 2008.8
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20pYF-2 Kondo-Fano effect in a side-coupled double quantum dot
Sasaki S., Tamura H., Miyashita S., Maruyama T., Akazaki T., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 593 - 593 2008.8
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20pYF-3 Spin-accumulation effect of the Kondo effect of a semiconductor quantum dot
Kobayashi T, Tsuruta S, Sasaki S, Fujisawa T, Tokura Y, Akazaki T
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 593 - 593 2008.8
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23aQG-1 Local NMR on the Quantum Hall Regime
Kawamura Takashi, Hayakawa Jun-ichiro, Onomitsu Koji, Miyashita Sen, Fujisawa Toshimasa, Yusa Go
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 429 - 429 2008.8
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20pYK-12 Intrinsic Gap in the V_T=1 Bilayer Quantum Hall State Revealed under Tilted Magnetic Fields
Giudici Paula, Muraki Koji, Kumada Norio, Fujisawa Toshimasa
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 598 - 598 2008.8
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20pYF-11 Decoherence of double-quantum-dot qubit by fluctuation of electrostatic environment
Shinkai G., Hayashi T., Ota T., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 63 ( 2 ) 595 - 595 2008.8
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24aWH-3 Coherent-oscillation characteristics of electrostatically coupled two pairs of double quantum dots
Shinkai G., Ota T., Hayashi T., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 63 ( 1 ) 672 - 672 2008.2
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24aWH-9 Modulation of the Kondo effect by the spin-polarized current injection
Kobayashi T, Tsuruta S, Sasaki S, Fujisawa T, Tokura Y, Akazaki T
Meeting abstracts of the Physical Society of Japan 63 ( 1 ) 673 - 673 2008.2
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Decoherence of nuclear spins in a GaAs quantum well probed by a submicron scale all-electrical NMR device
OTA T., KUMADA N., YUSA G., MIYASHITA S., FUJISAWA T., HIRAYAMA Y.
2007 1130 - 1131 2007.9
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21aTG-1 LT-STS imaging of density-of-states distribution for two-dimensional holes in a GaSb/InAs quantum well
Suzuki K., Kanisawa K., Perraud S., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 2 ) 675 - 675 2007.8
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21pTH-10 Spin effects in the ν_T=1bilayer system : a clue to the nature of the compressible-incompressible phase transition
Giudici P., Muraki K., Kumada N., Hirayama Y., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 2 ) 685 - 685 2007.8
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21pTH-5 Nuclear spin resonance induced by radio frequency electric field through the electron-nuclear spin coupling
Kumada N., Kamada T., Hirayama Y., Miyashita S., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 2 ) 684 - 684 2007.8
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21aTG-2 Influence of quantum confinement on donor bound states : a scanning tunneling spectroscopy study
Perraud S., Kanisawa K., Wang Z. Z., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 2 ) 675 - 675 2007.8
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18pTA-12 Local density of states in InAs/GaSb double quantum wells observed by Low-temperature STS
Suzuki K., Janer C., Kanisawa K., Perraud S., Ueki M., Takashina K., Hirayama Y., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 663 - 663 2007.2
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21aTA-7 Single-electron transport through single and double silicon quantum dots
Liu H. W., Fujisawa T., Inokawa H., Ono Y., Fujiwara A., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 690 - 690 2007.2
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21aTA-3 Zeeman Splitting in a Few-Electron Quantum Dot under Vector Magnetic Field
Shinkai G., Hayashi T., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 689 - 689 2007.2
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21pTA-5 Transport characteristics of a quantum dot with current injection by electron focusing
Kobayashi T, Tsuruta S, Kang S, Sasaki S, Tamura H, Fujisawa T, Tokura Y, Akazaki T
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 693 - 693 2007.2
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19pRC-3 Temperature Dependent Resistivity of a Two-Dimensional Electron System in a SiO_2/Si/SiO_2 Quantum Well
Takashina K., Renard V., Niida Y., Fujiwara A., Hirayama Y., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 670 - 670 2007.2
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18pRC-3 Spin texture in a bilayer ν=2 ferromagnetic state
Kumada N., Muraki K., Hirayama Y., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 658 - 658 2007.2
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18pRC-2 Decoherence due to dipole interaction between nuclear spins probed by resistivelydetected NMR
Ota T., Kumada N., Yusa G., Miyashita S., Fujisawa T., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 658 - 658 2007.2
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18pTA-13 Observation of percolation transition from localized to extended states in semiconductor quantum-well structures
Perraud S., Kanisawa K., Wang Z. Z., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 62 ( 1 ) 663 - 663 2007.2
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Electrostatic coupling between two double-quantum dots studies by resonant tunneling current
SHINKAI Gou, FUJISAWA Toshimasa, HAYASHI Toshiaki, HIRAYAMA Yoshiro
2006 814 - 815 2006.9
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29pXB-8 Counting statistics of double quantum dot using charge detection
Fujisawa T., Hayashi T., Tomita R., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 61 ( 1 ) 697 - 697 2006.3
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Real-time observation of charge state transitions in a double quantum dot
HAYASHI T., FUJISAWA T., TOMITA R., HIRAYAMA Y.
2005 406 - 407 2005.9
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19pWF-6 Energy relaxation mechanism in a double quantum dot
Hayashi T., Fujisawa T., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 60 ( 2 ) 522 - 522 2005.8
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Long Spin Relaxation Time Observed in a Lateral Quantum Dot
SASAKI Satoshi, FUJISAWA Toshimasa, HAYASHI Toshiaki, HIRAYAMA Yoshiro
2004 612 - 613 2004.9
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30aYA-10 Pulse measurement of spin relaxation time in a lateral quantum dot
Sasaki S., Fujisawa T., Hayashi T., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 59 ( 1 ) 707 - 707 2004.3
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28aYA-2 Charge qubit in semiconductor double quantum dot
Hayashi T., Fujisawa T., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 59 ( 1 ) 681 - 681 2004.3
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Electrical pulse measurement and single-electron dynamics in uantun dots
FUJISAWA Toshimasa
72 ( 10 ) 1309 - 1313 2003.10
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Decoherence of electric dipole rotation in a double quantum dot
Hayashi T., Fujisawa T., Cheong H. D., Jeong Y. H., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 58 ( 2 ) 597 - 597 2003.8
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Coherent oscillation of electric dipole in coupled quantum dot
Hayashi T., Fujisawa T., Cheong H. D., Jeong Y. H., Hirayama Y.
Meeting abstracts of the Physical Society of Japan 58 ( 1 ) 620 - 620 2003.3
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Spin state in a quantum dot with asymmetric barriers
Hayashi Toshiaki, Fujisawa Toshimasa, Hirayama Yoshiro
Meeting abstracts of the Physical Society of Japan 57 ( 2 ) 569 - 569 2002.8
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Photonl Assisted Tunneling in Single-electron Double Quantum Dot
Ono K., Kodera T., Wiel W.G. van der, Fujisawa T., Tarucha S.
Meeting abstracts of the Physical Society of Japan 57 ( 2 ) 569 - 569 2002.8
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24pXP-9 Orbital angular momentum relaxation and spin relaxation in a vertical quantum dot
Fujisawa T., G. Austing D., Tokura Y., Hirayama Y., Tarucha S.
Meeting abstracts of the Physical Society of Japan 57 ( 1 ) 627 - 627 2002.3
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Inelastic spin relaxation in vertical quantum dots
Fujisawa T, Tokura Y, Austing D. G, Hirayama Y, Tarucha S
Meeting abstracts of the Physical Society of Japan 56 ( 2 ) 544 - 544 2001.9
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Charge states and spin states in quantum dots
Fujisawa Toshimasa
Meeting abstracts of the Physical Society of Japan 56 ( 2 ) 554 - 554 2001.9
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Transicnt current spcctroscopy and spin relaxation of a vertical quantum dot
Fujisawa T, Tokura Y, Hirayama Y, Austind D. G, Tarucha S
Meeting abstracts of the Physical Society of Japan 56 ( 1 ) 597 - 597 2001.3
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Conductance suppression in weakly coupled double quantum dots
Hayashi Toshiaki, Fujisawa Toshimasa
Meeting abstracts of the Physical Society of Japan 56 ( 1 ) 597 - 597 2001.3
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Non-equilibrium tunneling current though long-lived excited in a quantum dot
Fujisawa T, Tokura Y, Hirayama Y
Meeting abstracts of the Physical Society of Japan 55 ( 2 ) 586 - 586 2000.9
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Transmission Type Rf Single Electron Transistor Operation of a Semiconductor Quantum Dot
FUJISAWA Toshimasa, HIRAYAMA Yoshiro
1999 252 - 253 1999.9
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半導体人工分子 (「量子輸送現象における新展開」特集号) -- (5.量子ドット)
樽茶 清悟, 藤澤 利正
固体物理 34 ( 5 ) 451 - 455 1999.5
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31a-ZB-4 Bosonic environment effect on double quantum dot
Fujisawa T., Oosterkamp T.H., W.G van der Wiel, Broer B.W., Aguado R., Tarucha S., Kouwenhoven L.P.
Meeting abstracts of the Physical Society of Japan 54 ( 1 ) 168 - 168 1999.3
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Quantum transport in semiconductor nanostructures - Resent research topics -
TARUCHA Seigo, TOKURA Yasuhiro, FUJISAWA Toshimasa, HIRAYAMA Yoshiro
67 ( 2 ) 167 - 171 1998.2
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6p-N-4 Single electron tunneling and single photon emission in quantum dot systems
Tarucha S., Fujisawa T.
Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 636 - 636 1997.9
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29p-S-2 Photon assisted tunneling in semiconductor quantum dot system
Fujisawa T.
Meeting abstracts of the Physical Society of Japan 52 ( 1 ) 612 - 612 1997.3
Research Projects
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Quantum state control of chiral plasmons in integer and fractional quantum Hall systems
Grant number：24K00552 2024.4 - 2029.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Grant amount：\18590000 （ Direct Cost: \14300000 、 Indirect Cost：\4290000 ）
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ブレーディングデバイスの原理検証
Grant number：24H00827 2024.4 - 2027.3
日本学術振興会 科学研究費助成事業 学術変革領域研究(B)
橋坂 昌幸, 藤澤 利正
Grant amount：\84240000 （ Direct Cost: \64800000 、 Indirect Cost：\19440000 ）
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Developing thermoelectric devices based on non-thermal metastable states in low-dimensional electron systems
Grant number：23K17302 2023.6 - 2029.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)
Grant amount：\26000000 （ Direct Cost: \20000000 、 Indirect Cost：\6000000 ）
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トポロジーが紡ぐ物質科学のフロンティア の総括
Grant number：20H05606 2020.4 - 2021.3
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)
川上 則雄, 藤澤 利正
Grant amount：\3900000 （ Direct Cost: \3000000 、 Indirect Cost：\900000 ）
研究終了領域として「トポ物質科学」で行ってきた5年間の領域活動および研究成果をとりまとめ、本領域で得られた成果を社会・国民に向けて発信することを目的としている。この目的のため、得られた成果の情報収集を行い、これまで領域ホームページに公開してきた国際活動、領域研究会、若手研究者育成、セミナー、論文発表、講演、アウトリーチ活動などの内容をさらに充実させた。以下に、R2年度の実績について要約する。
●研究成果・社会への還元の分析：成果とりまとめの一環として、これまで行ってきた領域活動に関する分析を行った。発表論文、招待講演、受賞などの情報収集を行うとともに、それらに含まれる研究成果の内容の分析を行った。●事務局の維持：令和2年度の年間を通じて、トポ物質科学に関する最新情報をホームページに掲載してきた。このため、京都大学のトポ物質科学事務局を維持し、WEB コンテンツの更新を含め全面的にサポートし、情報の完備に努めた。●国際会議・研究会を利用した領域成果の発信：これに関してはCovid-19による異常事態のため、多くの学術的会合が中止になり、これを遂行することが困難となった。しかしながら、年度の後半においてはオンラインの会議が可能になったので、これを利用して成果の発信を行うことができた。また、本領域で得られた成果をオープンアクセス雑誌に掲載するための経費をサポートした(研究発表項目で雑誌論文として記載したもの)。●基礎情報の取りまとめ、事後評価報告書の作成：領域活動に関する基礎情報は、各研究項目のメンバーと公募研究者からこれまで随時、成果情報のファイルを提出してもらい集積してきた。これらを基に、事後評価用の報告書、発表資料を作成した。Covid-19の影響で対面での会議を開催することが困難であったので、報告書作成の会議はオンラインで行った。 -
Nonequilibrium states of low-dimensional quasiparticles in a mesoscopic quantum Hall system
Grant number：19H05603 2019.6 - 2024.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
Grant amount：\199550000 （ Direct Cost: \153500000 、 Indirect Cost：\46050000 ）
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Electron-phonon coupled systems with phononic crystal resonators
Grant number：17K18751 2017.6 - 2023.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
Grant amount：\6500000 （ Direct Cost: \5000000 、 Indirect Cost：\1500000 ）
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Construction of Topo-Q International Network
Grant number：15K21717 2015.11 - 2020.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Kawakami Norio
Grant amount：\82160000 （ Direct Cost: \63200000 、 Indirect Cost：\18960000 ）
To activate the international exchange of researchers and accelerate the collaborations with overseas research projects on topological materials science, we have played a principal role in establishing the international network dubbed “Topo-Q”. In particular, our original programs such as the alliance workshops have enabled us to host an international platform for the community of researchers working on topological materials science. Furthermore, by fully making use of the researchers exchange programs, we have stimulated the international collaborations and nurtured young researchers.
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Transport properties of nanostructured topological materials
Grant number：15H05854 2015.6 - 2020.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Fujisawa Toshimasa
Grant amount：\260650000 （ Direct Cost: \200500000 、 Indirect Cost：\60150000 ）
In this project, we have intensively studied transport characteristics of artificial topological-material nanostructures by using semiconductor heterostructures and low-dimensional structures. Particularly we have developed novel topological quantum phenomena that cannot be seen in bulk materials and provided design concepts for novel nanostructured devices with topological materials. Specific results include (1) dynamics and non-equilibrium phenomena in chiral edge states in quantum Hall systems, (2) controlling helical edge states in quantum spin Hall systems, (3) spin transport based on spin-orbit locking and Weyl semimetals, (4) elemental technologies for controlling fractional charges in fractional quantum Hall systems, and (5) experimental and theoretical works for detecting Majorana quasiparticles. These results would provide physical understandings of topological quasiparticles and applications of topological-material nanostructures.
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Administration of Topological Materials Science
Grant number：15H05851 2015.6 - 2020.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Kawakami Norio
Grant amount：\89700000 （ Direct Cost: \69000000 、 Indirect Cost：\20700000 ）
To accomplish the purpose of Topological Materials Science project, we have made a concrete research plan, thereby activating the collaboration among the core projects and also the solicitation projects. To this end, we have held the annual meetings, the international conferences, the topology interactive meetings and the alliance workshops, and have conducted the young researchers programs to establish an interdisciplinary innovative research field. Through these activities, we have put particular emphasis on nurturing young researchers and establishing an international network of collaborations.
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Energy conversion on a quantum nano-device in a phonon resonator
Grant number：15K13271 2015.4 - 2017.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
Fujisawa Toshimasa, SATO Yuya, TAKASU Ryo
Grant amount：\4030000 （ Direct Cost: \3100000 、 Indirect Cost：\930000 ）
We have conducted a research on energy conversion between a semiconductor phonon system and an electronic system. Particularly an electron-phonon hybrid system is developed with a semiconductor double quantum dot in a surface-acoustic-wave phonon resonator. The device was fabricated by patterning a metal layer on the surface. Firstly, we evaluated fundamental acoustic characteristics such as the phonon band gap and resonator modes by using time-, frequency-, and space-resolved measurements for piezoelectric potential. Phonon scattering rate in the resonator is significantly enhanced by a factor of about 80, which can be enhanced further by optimizing the structure. Moreover we find novel spin-flip phonon assisted tunneling in the Pauli spin blockade regime. Intriguingly, this tunneling process probes Rabi splitting associated with coherent coupling between electron and phonon systems. The results encourage further development towards phonon version of cavity quantum electrodynamics.
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Nonequilibrium charge dynamics in quantum Hall edge channels
Grant number：26247051 2014.4 - 2019.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
Fujisawa Toshimasa, Hata Tokuro
Grant amount：\39780000 （ Direct Cost: \30600000 、 Indirect Cost：\9180000 ）
This project is aiming at understanding quantum many-body effects in charge and chargeless transport in edge channels of two-dimensional semiconductor systems in high magnetic fields and controlling non-equilibrium states in artificial low-dimensional electronic systems. We have successfully investigated Tomonaga-Luttinger behaviors like spin-charge separation, chargelss heat transport, and coupling to other degrees of freedom (phonons), as proposed initially. Extended works on fractional charge tunneling through a local fractional quantum Hall region and electron-phonon hybrid quantum systems were also performed. These works clearly encourage further studies on plasmon integrated circuits and quantum information channels in such systems.
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Control, measure, and transfer the quantum information in semiconductor nanostructures
Grant number：21102003 2009.7 - 2014.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
TOKURA Yasuhiro, OTA Takeshi, TARUCHA Seigo, YAMAMOTO Michihisa, FUJISAWA Toshimasa
Grant amount：\196560000 （ Direct Cost: \151200000 、 Indirect Cost：\45360000 ）
We have succeeded for the first time to demonstrate operations combining one-qubit unitary gate and two-qubit operation of spin qubits realized in quantum dot (QD) system. By improving device design, the world fastest x-rotation (127MHz) and z-rotation (50MHz) are achieved. We designed a micro-magnet structure that enable electron dipole spin resonance operations to individual spins in multi-QD array and succeeded in controlling three spins. In an InAs QD, the strength of spin-orbit interaction and g-tensor are precisely determined and controlled by gate. Combining tunnel-coupled quantum wires and an Aharonov-Bohm ring, the control of flying qubit is realized by the two-path interferometer. Using surface acoustic wave, single electrons are coherently transferred between distance QDs with success probability more than 90 %. We developed wide-band capacitance measurement system to detect the signal related to spin triplet state in a coupled QD system.
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Dynamics of electron wavepackets in semiconductor quantum structures
Grant number：21000004 2009 - 2014
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Specially Promoted Research
FUJISAWA Toshimasa, MURAKI Koji, KUMADA Norio, MURAKAMI Shuichi, HASHISAKA Masayuki, YOKOYAMA Takehito
Grant amount：\452790000 （ Direct Cost: \348300000 、 Indirect Cost：\104490000 ）
This project promotes fundamental research on dynamics of electron wavepackets in semiconductor quantum structures by extending the transport studies on semiconductor quantum dots, quantum Hall effect, and spin electronics. We have successfully revealed novel phenomena with coherent effects, electron correlations, non-equilibrium states, and non-linear effects in the dynamics of wavepackets for electrons and electron spins as well as their collective modes like plasmons and magnons.
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表面弾性波による半導体量子構造の電子状態の観測と制御
Grant number：19204033 2007 - 2009
日本学術振興会 科学研究費助成事業 基盤研究(A)
藤澤 利正, 熊田 倫雄
Grant amount：\45500000 （ Direct Cost: \35000000 、 Indirect Cost：\10500000 ）
本研究は、半導体量子構造における電子状態と表面弾性波(SAW)フォノンとの相互作用を研究し、電子状態を観測するスペクトロスコピー技術の確立や、電子格子相互作用の人為的制御を目指すものである。SAWのみならず、量子ホール領域で試料端を伝搬するエッジマグネトプラズモン(EMP)や、印加した高周波電界など様々な時間依存ポテンシャルによる効果を視野に入れ、二次元量子ホール系と零次元量子ドット系という代表的な量子構造での研究を進めている。今年度は、試作したSAWキャビティの評価、SAW伝搬のシミュレーションのほか、結合二重量子ドットの相関トンネリングの観測、EMP波束のスクリーニング効果、二層系量子ホール状態に関する成果を得た。主な内容は下記のとおりである。
1:結合二重量子ドットの電流ドラッグ効果:2つの二重量子ドット素子を流れる電流の相関に注目し、非常に大きな電流ドラッグ効果が得られることを示した。空間的に離れた2つの電子が同時にトンネルする2種類のコトンネリングを利用して、正または負の相関をもつドラッグ電流を得ることが出来る。その電流値の比は30%に達し、電流ミラー素子などへの応用が期待される。
2:EMP伝搬速度のメカニズム:我々は、量子ホールエッジ状態を伝搬するEMPの群速度がゲート電圧に依存することを見いだし、可変遅延制御素子として働くことを示してきた。そのメカニズムを検討し、ゲート電極による遮蔽効果が主な原因であることを確認した。ゲート電圧の変化によって、エッジチャネルと金属電極との距離が遠くなると、遮蔽効果が薄れ速度が上昇すると考えられる。このことは、複数のエッジチャネルに速度差が生じることを示唆しており、発展性が見込まれる。 -
Semiconductor Quantum Electromechanical Structures
Grant number：16206003 2004 - 2007
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
YAMAGUCHI Hiroshi, KANISAWA Kiyoshi, SAITO Tadashi, TATENO Kouta, FUJISAWA Toshimasa, HIRAYAMA Yoshiro
Grant amount：\48750000 （ Direct Cost: \37500000 、 Indirect Cost：\11250000 ）
One of the meet important results we obtained is the realization of on-chip micromechanical parametric resonator based on semiconductor heterostructures. We proposed the application to the basic device for a nanomechanical parametron computer and demonstrated one bit operation. Because the energy dissipation in the micro/nanomechanical resonator is extremely small, the nanomechanical parametron computer can be a highly power-efficient digital processing system. We also successfully demonstrate this parametric resonator can be used for parametric signal amplification and very sensitive charge sensors.
It is also a very important result that the vibration damping in semiconductor-based micromechanical resonator was controlled by carrier excitation. So far the damping control was performed by coupling the micromechanical resonator to optical cavity, which needs fine alignment of optics. In our new method, the fine tuning was made by laser wavelength adjustment, and we found that significant effects can be obtained at around the band gap wavelength. This indicates that the effect was caused by the carrier excitation and piezoelectric effects play important role. By making the effective damping negative, we also successfully realized self oscillation of mechanical cantilever.
Furthermore, the Micromechanical beam resonators were fabricated using a strained film grown on a relaxed In_0.1Ga_0.9As/In_0.1Al_0.9As buffer layers. The natural frequency of fundamental mode was increased by the applied tensile strain. In addition, nearly one-order of magnitude sharper resonance line shape was obtained for the best sample. This technique can be widely applied for improving the performance of resonator-based micro/nanoelectromechamcal devices.
We also made development of fabrication and measurement technique for semiconductor electromechanical devices, including 3D nanohthography, block co-polymer lithography, quantum dot electrometiy, nanoprobe technique, semiconductor nanowire growth. Although, they could not be integrated with electromechanical systems, they are promising for future detailed study of quantum electromechanical systems. -
高圧下での測定によるIII-V族化合物半導体中の欠陥準位に関する研究
Grant number：01790355 1989 - 1990
日本学術振興会 科学研究費助成事業 奨励研究(特別研究員)
藤澤 利正
Grant amount：\1900000 （ Direct Cost: \1900000 ）