応用物理学輪講 I
12月2日
[注意事項]
発表の10日前までに　office[at]ap.t.u-tokyo.ac.jp　宛てに「氏名」「指導教員」「発表題目（英語）」「要旨（英語）」「発表言語（英語または日本語）」を送付して下さい。
発表日
2022年12月2日（金）16：50～18：50

Aグループ

座長
土屋　叡本
指導
教員名
小林　洋平　教授
座長
友田　寛子
指導
教員名
武田　俊太郎　准教授
発表者名 藤本　雄人
指導教員名 齊藤　英治　教授
発表題目（英語） Nonlinear transport effects in a polar crystal
要旨（英語） Recently, nonlinear transport effects attract a lot of interest both experimentally and theoretically. One important example of such effects is a p-n junction. A p-n junction is formed by joining two types of semiconductors, which breaks not only the spatial inversion symmetry but also the translational symmetry. Other systems that may exhibit nonlinear transport effects include the bulk crystals belonging to the noncentrosymmetric point groups. However, as they are translationally symmetric, when the system has the time-reversal symmetry, the nonlinear transport effects are prohibited because the group velocities cancel out each other with respect to the crystal momentum *k *and *-k*. Therefore, time-reversal symmetry breaking with magnetization or magnetic field, electron correlation, or other effects must be involved. Here, we focus on the ferromagnetic polar crystal, in which both the inversion and time-reversal symmetries are broken, which triggers the nonlinear transport effects. In this presentation, I will talk about the experimental method, results and problems of my research.
発表言語 日本語
発表者名 堀部　聡平
指導教員名 齊藤　英治　教授
発表題目（英語） Nonreciprocal Parametric Amplification of Magnons
要旨（英語） Magnons, quanta of spin waves, can be excited by microwaves. Parallel parametric amplification is a nonlinear process that converts one microwave photon into two magnons at half of the microwave frequency and can excite various magnon modes. Surface modes, which can be excited in thin magnets, are particularly intriguing due to their nonreciprocity. In other words, their propagation direction can be reversed by the direction of applied static field. It is thus expected that the parametric amplification can be nonreciprocal when exciting surface modes, which is addressed in this study.
In the experiment, a ferrimagnet Y3Fe5O12 (Yttrium Iron Garnet, YIG) thin disk was nonuniformly excited by the parallel parametric amplification. Electrical measurement results showed nonreciprocity: whether the magnon is excited is dependent on the direction of the applied static field in a certain microwave power range. In this presentation, the concepts and experimental results of the nonreciprocal parametric amplification will be explained and discussed.
発表言語 英語

Bグループ

座長
冬鏡　澪
指導
教員名
小芦　雅斗　教授
座長
長吉　博成
指導
教員名
古澤　明　教授
発表者名 宮村　岳昂
指導教員名 中村　泰信　教授
発表題目（英語） Generation of a shaped microwave photon with frequency tunability using a fixed-frequency superconducting qubit
要旨（英語） Quantum state transfer between remote chips will be useful for scalable superconducting quantum computing. Itinerant microwave photons can be used for such coherent quantum communication[1] [2]. In this method, it is necessary to tune the frequency of microwave photons. Also, to make the transfer efficient, shaping the waveforms of emitted photons is required.
Here, we explain a new method to emit frequency-tunable microwave photons without any additional elements by utilizing the linewidth of a resonator.
We also explain the demonstration of the photon shaping method while maintaining the frequency tunability in case the resonator state has large decay and can be approximately eliminated. Compared to previous works, this method can reduce burdens to implement quantum state transfer via microwave photons. Moreover, our method relies on experimental data, so it can include the effects of every microwave element on the signal line.

[1] M. Pechal et al., Phys. Rev. X 4, 041010 (2014).
[2] P. Kurpiers et al., Nature 558, 264 (2018).
発表言語 英語
発表者名 宮本　樹
指導教員名 長谷川　達生　教授
発表題目（英語） Real-time Observation for Switching Dynamics of Ferroelectric-ferroelastic Domains in Plastic/Ferroelectric Crystals
要旨（英語） Plastic/ferroelectric crystals are a class of newly discovered molecular ferroelectrics, where ferroelectric and structural transition arises as the globular polar cations rotate or freeze. They are attracting attention for the solution processability and unique multiaxial ferroelectricity. 1-azabicyclo[2.2.1] heptanium perrhenate, above all, exhibits 4-axis spontaneous polarization at room temperature and outstanding ferroelectric properties [1], although the microscopic mechanism of its desirable switching characteristics, i.e. dynamics of ferroelectric-ferroelastic domain walls, remains to be explored with the goal of modern application.
In this study, we adopted the birefringent field-modulation imaging technique [2], an optical microscopy that utilizes the Pockels effect, to observe the behavior of the ferroelectric-ferroelastic domain walls during intermittent switching. We also performed a high-speed imaging experiment to directly observe the periodic dynamics of the domains under AC electric fields. I will introduce these measurement techniques and discuss distinctive domain dynamics in the presentation,

[1] J. Harada et al. J. Am. Chem. Soc. 141, 9349 (2019).
[2] Y. Uemura et al. Phys. Rev. Appl. 14, 024060 (2020).
発表言語 日本語
発表者名 村田　拡輝
指導教員名 芦原　聡　教授
発表題目（英語） Optical Amplification of High-Repetition-Rate, Mid-Infrared Ultrafast Pulses toward High Harmonic Generation in Solids
要旨（英語） The evolution of high-power ultrafast lasers has not only developed laser applications in natural sciences and engineering, but also discovered non-perturbative strong-field phenomenon. Recently, high harmonic generation (HHG), a representative strong-field phenomena, has been found to occur in solids as well as in gases. Advantages of the solid-state such as the HHG efficiency and polarization control leads to the expectation to develop novel XUV light sources.
To generate higher harmonics without damaging interaction media, Mid-Infrared (MIR) pumps are more suitable than visible light pumps. However, the conventional method to obtain high power MIR pulses such as Ti:Sapphire-based system suffers low repetition rate because of parametric conversion.
The purpose of this study is to obtain sufficient pulse energy of high-repetition-rate MIR pulses for HHG in solids by the amplification of the output pulses from the MIR laser oscillator. In this presentation, the design of the amplifier and the current status of the amplifying crystals the will be reported.
発表言語 日本語
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