Coherent control of Bloch electrons by external driving fields

2015 Fiscal Year Final Research Report

• Project/Area Number: 25400330
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kayanuma Yosuke 東京工業大学, 応用セラミックス研究所, 特任教授 (80124569)
• Co-Investigator(Kenkyū-buntansha): NAKAMURA Kazutaka 東京工業大学, 応用セラミックス研究所, 准教授 (20302979)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: バンドギャップ変調 / 動的局在 / コヒーレント制御 / 位相干渉効果 / 過渡反射スペクトル / 位相ロック２連パルス / ディラック円錐

Outline of Final Research Achievements

We clarified the peculiar features of the quantum state of Bloch electrons under the influence of oscillating elctromagnetic fields. It is found that, by choosing the ratio of the amplitude and the frequency of the field, it is possible to reduce, or even collapse the band gap of the Bloch states. It has been demonstrated that we can control the Bloch-Zener tunneling of electrons by applying this principle. Furthermore, we have shown that the morphology of the Dirac cone in graphene can be changed drastically by irradiating electromagnetic fields with various polarization. As an example, we have shown that the Dirac cone is deformed into Dirac wedge, where a one-dimensional manifold of zero-gap state emerges.
We have formulated the theory for the generation and detection of coherent phonons in bulk crystals. It was shown that by using the phase-locked double pulses, the coherence of the electron-phonon coupled state can be controlled and observed via the transient reflection modulation.

Free Research Field

物性理論