2005 Fiscal Year Final Research Report Summary
Dynamics and its coherent control of equilibrium and nonequilibrium electrons in semiconductor quantum structures
| Project/Area Number |
13002002
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Review Section |
Physics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KOMIYAMA Susumu The University of Tokyo, Department of Basic Science, Professor, 大学院・総合文化研究科, 教授 (00153677)
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| Co-Investigator(Kenkyū-buntansha) |
IKUSHIMA Kenji The University of Tokyo, Department of Basic Science, Research associate, 大学院・総合文化研究科, 助手 (20334302)
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| Project Period (FY) |
2001 – 2005
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| Keywords | Terahertz imagingt / Terahertz microscope / auantum Hall edge channel / Quantum dot / Single-photon detection / nuclear spin |
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| Research Abstract |
The purpose of the project research is to achieve deeper understanding of the physics of semiconductor quantum structures by developing novel measurement methods based on the technique of single-terahertz-photon detection in quantum dots, and to explore the method of controlling quantum states of semiconductor many body systems. The achievements in the first category are (i) the development of novel scanning-type terahertz microscopes with unprecedented sensitivity and spatial resolution by using ultra-highly sensitive detectors and (ii) the study of dynamics of non-equilibrium electron generation in quantum Hall devices by applying the microscopes. The biggest achievement is the realization of a terahertz photon-counting technique by incorporating quantum-dot terahertz-photon detectors into scanning microscopes (spatial resolution, 50 □m): By applying the measurements systems, dynamics of non-equilibrium electron generation of quantum Hall bars at hot spots (electron entry and exit corners), gate-bias induced potential barriers, and edge states. The achievements in the second category are based on the realization of electrically manipulating nuclear spin system by using spin-split edge channels in quantum Hall bars; viz., nuclear-spin polarization has been generated, coherently controlled, and sensitively detected by means of the edge channels: By exploiting these effects, a novel nuclear-spin microscopy with a nano-meter resolution has been developed. By applying the technique, local nuclear-spin polarization in GaAs quantum Hall bars has been clarified with nano-meter accuracy, and the dynamics of its generation and diffusion have been unveiled. In addition, it is found that the slope of confining potential at the edge states channels crucially affects the efficiency of generating nuclear spin polarization, opening up the new possibility of probing quantum Hall edge channels with the probe of nuclear spin polarization.
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