応用物理学輪講 I
7月12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7月12日（金）16：50～18：50

Aグループ

座長
伊豆　駿佑
指導
教員名
福谷　克之　教授
発表者名 宮本　尚樹
指導教員名 吉岡　孝高　准教授
発表題目（英語） Laser Cooling for Precision Spectroscopy of Positronium
要旨（英語） Positronium is a bound state of an electron and a positron, both of which are leptons. This unique property makes it a stringent testing ground for fundamental theories of physics, such as quantum electrodynamics, through the measurement of its transition frequencies.
Stopping the motion of positronium, thus obtaining a low temperature, is crucial for the accuracy of these measurements. Last year, we succeeded in one-dimensional laser cooling, approaching the recoil limit temperature. Building on this success, we have been developing an experimental system to extend this technique to three-dimensional laser cooling.

In this presentation, we will introduce the design of our cooling and spectroscopic experiments, as well as the current progress towards a method for generating positronium with a small spatial spread, which is essential for these experiments.
発表言語 日本語
発表者名 三宅　孝明
指導教員名 沙川　貴大　教授
発表題目（英語） Empirical analysis of Hamiltonian dynamics error for resource estimation in fault-tolerant quantum computing
要旨（英語） One of the promising applications of quantum computers is large-scale quantum dynamics simulation. The most famous algorithm for this purpose is called Trotterization, which approximates the time evolution operator using product formulas. Estimating the resources required for implementing these algorithms is crucial for verifying and achieving quantum supremacy early. In this presentation, I will discuss methods for resource reduction through parameter optimization and improvements in resource estimation by revising error metrics.
発表言語 日本語
発表者名 吉冨　成哉
指導教員名 求　幸年　教授
発表題目（英語）
要旨（英語）
発表言語

Bグループ

座長
井ノ上　慎一
指導
教員名
中村　泰信　教授
発表者名 山口　大輝
指導教員名 十倉　好紀　卓越教授
発表題目（英語） Multiferroics in a helimagnetic metal controlled and detected through non-reciprocal transports
要旨（英語） In multiferroic materials, more than one of the primary ferroic properties coexist in the same phase, for example, ferromagnetism and ferroelectricity (electric polarization). The properties of multiferroics have been intensely investigated in insulators, in which the definition of electric polarization is trivial. It has been theoretically and experimentally established, in insulators, that a type of helical magnetic structure induces an electric polarization, which means the helimagnetic structure can exhibit multiferroic properties if there is a spontaneous net magnetization at the same time. The same mechanism can be applied to the case of metallic materials, i.e. one can also define an electric polarization in metallic helimagnets. We have figured out a way to control and detect the polarization in a metal through non-reciprocal electric transports. In this talk, the details of the technic are going to be explained along with experimental steps such as micro-device fabrication.
発表言語 日本語
発表者名 村田　好登
指導教員名 高橋　陽太郎　准教授
発表題目（英語） Mode-mode coupling of spin excitations in a spin spiral hexaferrite
要旨（英語） Anharmonic mode coupling of phonon in coherent process has been attracting attentions in recent years. Through this process, the direct excitation of infrared-active phonon creates the off-resonant excitation of Raman-active phonon. This process can be explained as the shift of potential minimum of the Raman-active phonon, which induce the modulation of crystal structure.
We think this anharmonic process can also be applied to spin excitation, focusing on multiferroics. In this presentation, I will show the demonstration of indirect spin excitation in multiferroic hexaferrite using terahertz radiation and discuss the model which can explain this process.
発表言語 日本語
発表者名 結城　賢志
指導教員名 中村　泰信　教授
発表題目（英語） Fast readout of a superconducting qubit with a nonlinear Purcell filter using an auxiliary pulse
要旨（英語） The dispersive readout is a successful technique to quickly and accurately readout a state of a superconducting qubit. It uses the qubit-state-dependent frequency shift of a resonator dispersively coupled to the qubit.
The nonlinear Purcell filter was proposed as a means to realize a fast dispersive readout of the qubit while suppressing its decoherence due to thermal noise in the readout resonator. It was demonstrated that the driven steady state of this filter exhibits bifurcation that improves the signal-to-noise ratio of the readout. In this study, we aim for a further acceleration of the readout using the bifurcation phenomenon by employing an auxiliary pulse in addition to the conventional readout pulse.
発表言語 英語
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