| Project/Area Number |
18K03479
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
|
|---|
| Research Institution | University of Tsukuba |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2018-04-01 – 2021-03-31
|
| Project Status |
Completed (Fiscal Year 2020)
|
| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
|
|---|
| Keywords | 量子状態制御 / 電子スピン / 量子ドット / 非平衡状態 / フォノン / 位相干渉現象 / スピン・軌道相互作用 / 振動電場 / 量子マスター方程式 / 量子測定 / 散逸 / 量子フィードバック |
|---|
| Outline of Final Research Achievements |
I had conducted a research on the control of quantum system. Coherent spin dynamics in coupled quantum dots which are tunnel coupled to reservoirs is theoretically studied using Floquet quantum master equation method. It is found that the effect of modulation of the tunnel coupling is more effective than the modulation of the potential energy of the quantum dots. Moreover, the modulation of the spin-orbit interaction is found to enhance the coupling. When one increase the microwave amplitude, a dark state emerges. In the analysis with finite electron-phonon coupling, in addition to the conventional energy relaxation process, we found that decoherence process depending on the driving frequency. We also found a unique spin dynamics induced by a non-equilibrium phonon system. Quantum weak measurement on a small quantum system may reveal significant back-action effect and quantum phase information can be acquired with the charge measurement.
|
| Academic Significance and Societal Importance of the Research Achievements |
本研究で得られた知見により、量子ドット中の電子のコヒーレント制御の効果を高める指針が得られた。また今回考察した方法により量子ドット中のスピン・軌道相互作用の大きさを見積もるための条件を明らかにでき、スピンを用いた量子情報処理に向けて有益な知見が得られた。またマイクロ波の振幅の増大が、単に量子系の制御速度を向上させるだけでなく、暗状態の生成や位相緩和レートの増大、ラビ振動の飽和をもたらすなど様々な非線形効果をもたらすことを見出したことは、量子系の制御速度には原理的な上限があることを示し、今後の量子情報処理系の設計に関わる重要な知見をもたらした。
|
