| 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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| 次年度使用額が生じた理由 |
The reason for which not all of the budget was used during this fiscal year is that, because of the global pandemic, travel restrictions where strongly enforced and all conference or collaboration related travel could not be undergone. I hope to be able to travel in the future, to present and promote the results of the Kakenhi project at international conferences and to establish future international collaborations with other scientists working on this topic.
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