Experimental Study on Quantum Coherence in Solids

固体中量子相干性的实验研究

• 批准号: 13304029
• 负责人: KATSUMOTO Shingo
• 金额: $ 26.29万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13304029/
• 关键词: quantum dot; quantum decoherence; spin flip; Kondo effect; Fano effect; Coulomb peak; quantum anti-dot; edge state; ファノ効果; クーロンピーク; 量子コヒーレンス; デコヒーレンス; 近藤状態; スピン偏極キャリア; Aharonov-Bohm効果; 単電子トンネリング

We have observed, for the first time, clear sign of the Fano effect, which is a consequence of phase-shift and interference in a combined system of a quantum dot and a quantum ring. The observation leads to new knowledge of quantum coherence, e.g., the nature of Fano parameter. We have also applied this effect to investigate various problems on quantum coherence. For example, we have clearly observed electrostatic control of quantum phase and found a new theoretical method to treat thermal broadening of the quantum phase, which is applied to analyze experimental results. Especially, we have given a partial answer to a long standing problem of "in-phase Coulomb peaks". We further found the existence of strongly coupled states in quantum dots and multi-level transport through an ordinal resonant tunneling and co-tunneling through a strongly coupled state results in Fano interference in a quantum dot without any outer reference arm. External magnetic field causes focusing of strongly coupled states and smooth transition to outmost edge states is observed.We have investigated the relation between the spin states in quantum dots and the quantum coherence by a quantum ring structure. We have found that the spin scattering causes quantum decoherence through the formation of quantum entangled states between a local spin and a spin of traversing electron.We have shown that coherent control of electronic path through magnetic decoration on two-dimensional electrons. We have found a new quantum oscillation in magnetoresistance of quantum anti-dot systems.

我们第一次观察到了Fano效应的明显迹象，这是量子点和量子环组合系统中相移和干涉的结果。这一观察导致了量子相干性的新知识，例如，Fano参数的性质我们还将这种效应应用于研究量子相干性的各种问题。例如，我们已经清楚地观察到量子相位的静电控制，并找到了一种新的理论方法来处理量子相位的热加宽，并将其应用于分析实验结果。特别是，我们已经给出了一个长期存在的问题的“同相库仑峰”的部分答案。我们进一步发现了量子点中存在强耦合态，以及通过有序共振隧穿和共-共振隧穿的多能级输运。在没有外参考臂的量子点中，通过强耦合态的隧穿将导致Fano干涉.外磁场使强耦合态聚焦，并观察到向最外边缘态的平滑跃迁.我们研究了量子点中自旋态之间的关系量子点和量子环结构的量子相干性。我们发现自旋散射通过在局域自旋和穿越电子自旋之间形成量子纠缠态而引起量子退相干，并通过对二维电子的磁装饰来实现对电子路径的相干控制。在量子反点系统的磁电阻中发现了一种新的量子振荡。

项目成果

H.Aikawa, K.Kobayashi, S.Katsumoto, Y.Iye: "Spin-flip Process and Quantum Decoherence in a Quantum Dot"Physica E. 22. 474-477 (2004)

H.Aikawa、K.Kobayashi、S.Katsumoto、Y.Iye：“量子点中的自旋翻转过程和量子退相干”Physica E. 22. 474-477 (2004)

H.Aikawa, K.Kobayashi, T.Nakanishi: "Electronic States in Quantum Dots and Phase Shift of Transparent Wave"Butsuri (issued by the Physical Society of Japan). (in press). (2004)

H.Aikawa、K.Kobayashi、T.Nakanishi：“量子点中的电子态和透明波的相移”Butsuri（日本物理学会发行）。

M.Hara, A.Endo, S.Katsumoto, Y.Iye: "Transport in a two-dimensional electron-gas narrow channel with a magnetic field gradient"Physical Review B. vol.69. 153304-1-153304-4

M.Hara、A.Endo、S.Katsumoto、Y.Iye：“具有磁场梯度的二维电子-气体窄通道中的传输”物理评论 B. vol.69。

M.Hara, A.Endo, S.Katsumoto, Y.Iye: "Transport in Ferromagnet/Semiconductor 2DEG Hybrid Network Structure"Physica E. vol.22. 345-348 (2004)

M.Hara、A.Endo、S.Katsumoto、Y.Iye：“铁磁体/半导体 2DEG 混合网络结构中的传输”Physica E. vol.22。

K.Kobayashi, H.Aikawa, S.Katsumoto, Y.Iye: "Reduction of quantum decoherence in non-local resistance measurement"Microelectronic Engineering. 63. 752-789 (2002)

K.Kobayashi、H.Aikawa、S.Katsumoto、Y.Iye：“非局部电阻测量中量子退相干的减少”微电子工程。