| 研究課題/領域番号 |
20K14417
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| 研究種目 |
若手研究
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| 配分区分 | 基金 |
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| 審査区分 |
小区分13030:磁性、超伝導および強相関系関連
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| 研究機関 | 沖縄科学技術大学院大学 |
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研究代表者 |
POLOGOMEZ Juan 沖縄科学技術大学院大学, 量子システム研究ユニット, 研究員 (90867962)
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| 研究期間 (年度) |
2020-04-01 – 2022-03-31
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| 研究課題ステータス |
交付 (2020年度)
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| 配分額 *注記 |
3,510千円 (直接経費: 2,700千円、間接経費: 810千円)
2021年度: 1,690千円 (直接経費: 1,300千円、間接経費: 390千円)
2020年度: 1,820千円 (直接経費: 1,400千円、間接経費: 420千円)
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| キーワード | Bose gases / Impurities / BEC / Vortices / Machine Learning / Quantum dissipation / Ultracold atoms / Polarons |
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| 研究開始時の研究の概要 |
Understanding and controlling dissipation in closed quantum systems will be paramount for the success of future quantum devices. Although quantum mechanics does not intrinsically include dissipation, it can appear as a dynamical response of a subsystem coupled to its effective environment. In this study I will focus on the seminal Bose polaron problem in the experimentally relevant system of an impurity coupled to an ultracold Bose gas. The main objective is to quantitatively describe the relationship between the impurity’s dissipative motion and the underlying excitations of the Bose gas.
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| 研究実績の概要 |
The main goal of this scientific project is to study the response of an impurity embedded in a Bose gas in which multiple excitations exist.
The initial part of the research project focused on investigating different excitation appearing in Bose-Einstein condensates in one and two dimensions.
In the one-dimensional case, I have studied low-energy excitations in the form of shock waves using multiple theoretical and numerical approaches. In addition, I have also investigated dissipative motion of impurities in spin-orbit coupled Bose-Einstein condensates (BECs). These present exotic low-energy excitations in their stripe phase of matter.
In the two-dimensional case, I have studied vortices - which are excitations appearing in rotating BECs. For these studies, I used mean field approaches as well as new techniques based on Machine Learning alorithms. In the Machine Learning study, I investigated the detection of such vortex excitations in the presence of low-energy phonons.
These achievements have lead to four successful publications in international journals. The published material is mostly related to excitations in Bose gases, while the study on impurities is still in its writing stage and will be ready for submission within one or two months from the submission date of this report.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The initial work plan for the first year included - for the first six months - the development of the numerical codes needed to perform the main research project. The numerical codes have been developed and allow for the study of single and multiple impurities in BECs as well as the study of the bulk excitations. An extension of the codes has also been developed for studying spin-orbit coupled BECs. These type of system was included in the original project plan as an interesting system for studying the dissipative motion of impurities.
The next steps of the project, including the study of the the response of an impurity to particular excitations as well as its dissipative motion have also been executed. In particular, the work done was focused on the dissipative motion of impurities in a lattice formed by the stripe phase of a spin-orbit coupled BEC. This work is now in its writing stage, having been otherwise finalized, and will be ready for submission soon, within one or two months from now.
In addition, a follow-up project with multiple impurities is being initiated, with the purpose of continuing the study of spin-orbit coupled BECs.
Other tightly-related projects have been developed, all based on the study of excitation in BECs. In one dimension, I investigated shock waves and their universal features for different interatomic interactions within the Bose gas. In two dimensions, I have worked on vortices, both in their ground state as well as when other low-energy excitations are present in the system. The studies were successfully published in international journals.
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| 今後の研究の推進方策 |
The results of this project will be presented in international conferences (when the present context will allow for attending such events) and can lead to future projects related to dissipative motion of impurities in BECs. There are no major changes to the work plan. In the future I plan to continue the research of dissipative motion considering the particular excitations of the underlying bulk system. I might include new techniques based on machine learning as I have already gained some experience while investigating vortex excitations and their dynamics in the presence of phononic excitations.
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