2017 Fiscal Year Annual Research Report
Time evolution of topological magneto-optics and superconducting qubits
| Project/Area Number |
16F16027
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
NORI FRANCO 国立研究開発法人理化学研究所, 創発物性科学研究センター, グループディレクター (50415262)
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| Co-Investigator(Kenkyū-buntansha) |
LI ZHOU 国立研究開発法人理化学研究所, 創発物性科学研究センター, 外国人特別研究員
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| Project Period (FY) |
2016-10-07 – 2019-03-31
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| Keywords | topological materials / flat-band / Gaussian quantum states |
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| Outline of Annual Research Achievements |
I have finished a paper "Nonlinear response in non-centrosymmetric topological materials” and submitted to Phys. Rev., the paper is under review now. I have used the generalized Kubo formula to explain nonlinear phenomena in topological insulators.
I have collaborated with Dr. Clemens to work on a project on flat-band and finished a paper "Lifetime of flatband states” submitted to Phys. Rev., the paper is under review now. I have developed a numerical method to exactly study the time evolution of Gaussian quantum states, the method is for one dimension and can be generalized to two and three dimensions.
I have attended three international conferences and delivered three talks separately. I have been invited by Prof. Zubin at Purdue University to visit his group and delivered a talk in Condensed Matter Seminar at Purdue.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
I proposed to finish a paper on second harmonic generation in topological insulators, now the paper titled "Nonlinear response in non-centrosymmetric topological materials” is finished and submitted to Phys. Rev.
I proposed to study the time evolution of quantum states, and now in collaboration with another researcher at RIKEN, I finished part of this study, our work is submitted to Phys. Rev.
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| Strategy for Future Research Activity |
I plan to continue work on the two projects in FY2018.
1. For the nonlinear response in topological insulators, which is related to a perturbation expansion on electric field E based on the dipole approximation. If one think about perturbation theory based on multipole expansion, an exotic term called toroidal moment appear as an independent term, which is related to the magnetoelectric effect. The magnetic toroidal dipole can be imagined as the field of a solenoid bent into a torus. It requires the breaking of inversion (parity) symmetry as the second harmonic generation does.
2. For the flat-band project, now the numerical method to treat disorder is for one dimension, I will continue to develop the method to work for two and three dimensions. We work on a cross-stitch model, in the future study other complicated models based on natural and artificial systems may be considered.
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