2000 Fiscal Year Final Research Report Summary
Formation of isolated artificial two-level system in solid devices
| Project/Area Number |
10450014
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | The Institute of Physical and Chemical Research (RIKEN) |
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Principal Investigator |
ISHIBASHI Koji The Institute of Physical and Chemical Research (RIKEN), 半導体工学研究室, 先任研究員 (30211048)
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| Project Period (FY) |
1998 – 2000
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| Keywords | quantum dots / coupled quantum dots / Coulomb blockade / zero-dimensional quantum level / carbon nanotubes / two-dimensional electron gas |
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| Research Abstract |
The aim of the project is to realize an artificial two-level system using coupled quantum dots, where the single electron charging effect (Coulomb blockade) and zero-dimensional quantum levels are important. To form the quantum dot, we first used surface gate technique, where the lithographically made surface gates are deposited on top of the GaAs/AlGaAs 2 dimensional electron gas wafer. The Coulomb blockade and zero-dimensional quantum levels have been clearly observed below 1 Kelvin in a single dots, and resonant tunneling between two discrete quantum levels in double dots have been observed with an important Coulomb blockade effect. But, coherence in the two-dot system is to be studied further. The signal of the change in single electron charge have been obtained in double-dot system, which is important for the read-out of the two level system.
To increase the operation temperature of the coupled quantum dot, we have developed the process of the formation of quantum dots in single-wall carbon nanotubes which has an extremely small diameter of about one nanometer. The charging energy and the mean level spacing have been obtained which is larger by more than an order compared with the dot made by standard electron beam lithography. Finally, we have developed a technique to form coupled quantum dots in carbon nanotubes.
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