応用物理学輪講 I
11月29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
2024年11月29日（金）16：50～18：50

Aグループ

座長
中田　勇宇
指導
教員名
木村　隆志　准教授
座長
中野　遼太
指導
教員名
Max　Hirschberger　准教授
発表者名 永山　裕一
指導教員名 木村　隆志　准教授
発表題目（英語） Soft X-ray Reflection Ptychography Imaging
要旨（英語） Soft X-rays, with their energy levels matching the absorption edges of multiple elements, have been studied as a promising tool for elemental distribution imaging through soft X-ray ptychography. However, conventional optical setups require the transmission of synchrotron radiation through the sample, making it impossible to observe materials on opaque substrates or the surfaces of thick samples.
In this study, we introduce a reflective geometry to measure total reflection of X-rays at the sample surface. This approach enables the observation of new types of samples and physical properties that are inaccessible with transmission-based methods. Simulations were conducted to reconstruct real-space images from curved diffraction patterns obtained near the critical angle. Additionally, we present the current experimental setup and sample preparation being developed at the large synchrotron facility, SPring-8.
発表言語 日本語
発表者名 西澤　優
指導教員名 武田　俊太郎　准教授
発表題目（英語） Arbitrary temporal waveform shaping of optical non-Gaussian quantum states
要旨（英語） Today, there is global interest in developing quantum computers, and various types of quantum computers have been proposed to achieve this. Among them, the photonic approach stands out due to its numerous advantages, such as operating at room temperature and pressure, high clock frequency, and potential applications in optical communication.
In the photonic approach, we perform computation using quantum states generated within the light wave packets with specific temporal waveforms. Here, to surpass classical computation, it is essential to use non-Gaussian quantum states. Moreover, by using quantum states with optimized temporal waveforms, it is possible to enhance the interference of lights, reduce noise, and enable high-speed information readout, thereby improving information processing efficiency.
However, waveform shaping of non-Gaussian states is difficult. This is because, with conventional generation methods, the temporal waveform of non-Gaussian quantum states was determined by the experimental setup.
To solve this problem, we have proposed a new method for arbitrary waveform shaping of non-Gaussian states. This method involves an intensity-modulation system for the trigger light, which is the light detected during the generation of non-Gaussian states, and theoretically, it enables arbitrary waveform shaping for multiple non-Gaussian states within a single setup. In this presentation, I will introduce our waveform shaping method and present our experimental results demonstrating waveform shaping for a single-photon state.
発表言語 英語
発表者名 野田　源文
指導教員名 関　真一郎　准教授
発表題目（英語） Realization of versatile spin textures in a centrosymmetric rare-earth magnet
要旨（英語） Topologically protected spin swirling structures, such as skyrmions, have attracted attention for next-generation magnetic memory applications. Previously, extensive studies have successfully identified skyrmion-hosting materials with non-centrosymmetric systems. These asymmetries cause the relativistic Dzyaloshinskii-Moriya (DM) interaction, which inherently prefers twisted spin configurations and plays a crucial role in topological spin texture formation.

Recently, however, these spin textures have been observed in centrosymmetric Gd compounds accompanied by itinerant-electron-mediated spin interactions. In these skyrmion-hosting materials, extremely small skyrmions are realized, and thus, they are anticipated for future applications.

This study focused on a Gd-based compound with tetragonal space group I4/mmm and measured its physical properties. This presentation will discuss detailed spin textures realized in this compound based on the X-ray scattering measurement.
発表言語 日本語

Bグループ

座長
永濱　壮真
指導
教員名
十倉　好紀　卓越教授
座長
畠中　友也
指導
教員名
森本　高裕　准教授
発表者名 橋爪　智紀
指導教員名 山本　倫久　教授
発表題目（英語） Single Electron Sources in 2DEG for electron quantum optics
要旨（英語） Electron quantum optics is an attempt to reproduce quantum optics using electrons. This is achieved by forming a two-dimensional electron gas within a GaAs/GaAsAl semiconductor heterostructure. By applying Lorentzian voltage pulses to the contacts, a single electron can be excited without exciting additional holes. Since there is no extra electron-hole excitation, decoherence due to additional electron-electron interactions is less likely to occur, and shot noise is reduced due to fewer electrons and holes. These properties indicate that Levitons can be treated as “flying qubits.” Furthermore, flying qubits can be manipulated by treating quantum point contacts as beam splitters in quantum optics. This is expected to make it possible to reproduce an optical quantum computer using electrons in semiconductors.
発表言語 日本語
発表者名 濵野　直紀
指導教員名 香取　秀俊　教授
発表題目（英語） Development of a frequency-stabilized 2.92 um laser for continuous cooling in optical lattice clocks
要旨（英語） The Sr optical lattice clock has a fractional frequency uncertainty of 10^. However, in the current design of optical lattice clocks, it is impossible to simultaneously perform both cooling and spectroscopy of the atoms, which limits the improvement in laser frequency stability to 1/√t for an averaging time t.
We are developing a next-generation optical lattice clock that allows continuous cooling and spectroscopy to improve stability as 1/t. The key to achieving continuous operation lies in the laser cooling on the 2.92 um transition, which does not share energy levels with the spectroscopic transition, thus allowing for simultaneous cooling and spectroscopy.
In this study, I am developing a 2.92 um laser for the optical lattice clock. Since this cooling transition requires a narrow-linewidth laser, I convert the 2.92 um light to 1.46 um, where a narrow-linewidth laser can be used as a stable reference. This presentation will discuss the development of the wavelength conversion device for the 2.92 um laser, as well as our ongoing efforts toward achieving frequency stabilization.
発表言語 英語
発表者名 廣田　和希
指導教員名 古澤　明　教授
発表題目（英語） Experiment of generating highly squeezed vacuum state
要旨（英語） Furusawa-Endo lab is studying optical continuous variable measurement based quantum computer. It has the advantage of operating at room temperature and high clock frequency.
In this scheme, a quantum state called squeezed vacuum state is used and achieving higher quality of squeezed vacuum state is important to reduce noise in each calculation step.
I will explain in detail how it is related to noise in each calculation and my experiment toward measuring better quality state than previous studies.
発表言語 英語
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