2003 Fiscal Year Final Research Report Summary
Physics of small superconductors and its application to quantum computing devices
| Project/Area Number |
14540321
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅱ(磁性・金属・低温)
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
EBISAWA Hiromichi Tohoku University, Graduate School of Information Sciences, Professor, 大学院・情報科学研究科, 教授 (90005439)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Masahiko Tohoku University, Graduate School of Information Sciences, Associate Professor, 大学院・情報科学研究科, 助教授 (60301040)
IMAMURA Hiroshi Tohoku University, Graduate School of Information Sciences, Associate Professor, 大学院・情報科学研究科, 助教授 (30323091)
|
|---|
| Project Period (FY) |
2002 – 2003
|
| Keywords | small superconductor / single-electron-transistor / SQUID / Parity effect / Little-Parks oscillation / quantum bit / vortex / superconducting network |
|---|
| Research Abstract |
Aiming to realize the quantum computers based on superconducting devices, we have investigated the basic physical properties of the small superconducting systems and also studied the mechanism of the manipulation and control of the quantum devices from a fundamental point of view. The followings are the results obtained by this research project:(1) We have studied the single-electron-transistor consisting of superconducting systems and clarified the nature of the quantum fluctuation of the voltage and its effects on the performance of the device. (2) Parity effects in a tiny SQUID are studied in terms parity projected grand canonical ensemble and clarified the effects of parity on the Josephson coupling energy. (3) The effects of the parity on the spin-injection and tunnel magneto-resistance in a superconductor is studied and clarified the relation between Coulomb blockade and spin accumulation. (4) Mesoscopic orbital magnetism in a superconductor-normal metal hybrid system and pointed out the enhanced fluctuations in diamagnetism due to mesoscopic effects. (5) Little-Parks effect in a one-dimensional superconductor is studied and it is found that the phase of the Little-Parks oscillation is reversed in tiny systems. (6) Physical properties and electronic properties of topological crystals are studied and, especially, found the appearance of specific node states in the Little-Parks oscillation of Moebius crystals. (7) The decoherence in a spin system coupling via RKKY interaction is studied and found that when the interaction is ferromagnetic, decoherence can be suppressed. (8) Phase transition and vortex structure in small superconducting networks are theoretically studied. (9) Vortex dynamics in a superconducting Corbino disk is theoretically studied.
|
