| 研究課題/領域番号 |
21K13856
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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 |
FOGARTY Thomas 沖縄科学技術大学院大学, 量子システム研究ユニット, スタッフサイエンティスト (60786987)
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| 研究期間 (年度) |
2021-04-01 – 2024-03-31
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| キーワード | quantum speed limits / orthogonality / interacting states / quantum control / quantum correlations / supersymmetry |
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| 研究実績の概要 |
In the past year I have published 3 main papers on this project. Two of these papers focussed on dynamics of quantum systems in supersymmetric
(SUSY) potentials. SUSY allows to build a hierarchy of degenerate potentials that can be mapped to one another through SUSY operators. In the first work I explored the quench dynamics of many-body states between different SUSY potentials showing that revivals of the initial state are persevered at periodic times, in comparison to quenches between arbitrary potentials [PRR 4 033014 (2022)]. Follow up work on shortcuts to adiabaticity (STAs) showed that SUSY can aid in quantum control, allowing to design STAs for a family of SUSY potentials using only information on their mutual SUSY operators [NJP 24 095001 (2022)]. This also allowed to relate the quantum speed limits (QSLs) of states with respect to their SUSY operators, showing that states in the same hierarchy have closely related QSLs and therefore dynamics.
The role of QSLs was further explored in interacting few-body systems which are used in a quantum heat engine [PRR 5 013088 (2023)]. Here the trap frequency and interaction are dynamically controlled allowing to realize an Otto cycle with enhanced performance due to the interactions. While dynamically controlling the interaction increases the QSL time and limits the power output, the enhancement obtained from the interactions still allows it outperform non-interacting cycles.
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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
Work on this project was delayed due to the COVID-19 pandemic and restrictions to travel in Japan and the rest of the world. For this reason planned conference trips and collaboration visits could not be undertaken. Work done with collaborators has also therefore been delayed, with different projects needing to be finished.
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| 今後の研究の推進方策 |
For the future work I will explore the controlled thermalization of quantum systems coupled to heat reservoirs. Using both shortcuts to adiabaticity and optimal control protocols I plan to design the coupling strength to speed up the equilibration of the system with the environment. Preliminary work will focus on the Caldirola-Kanai model, which allows to describe dissipative dynamics using a dissipationless Hamiltonian. Designing the control scheme for this simpler system should give insight into the full open system dynamics, even providing an approximate STA. Likewise computational control techniques can be used in this case, which rely on numerical optimization of the systems parameters. Furthermore, the quantum speed limit for equilibration can set the minimum timescale for the system to relax and will be dependent on the coupling strength and the spectral density of the bath.
The future plan also involves continuing close collaborations with experimental groups which are currently creating interacting quantum heat engines. The next step in these works is to consider dynamically driving the engines by tuning the trap frequency and interactions. QSLs inherently limit the operation time, STAs allow to approach this limit. In this work I will continue assisting in theoretical support of these groups, providing STAs and bounds on the operation time.
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| 次年度使用額が生じた理由 |
Due to COVID-19 travel restrictions the allotted amounts could not be used for international travel. Also planned research collaboration visits had to be rescheduled to 2023. For this reason the funds need to be used in the next financial year. These visits will be used to complete projects with collaborators in Ireland and Spain, along with a project in Tohoku.
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