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You are the th visitor since Jan. 17, 2000.
Last updated on Nov. 8, 2000.
This page is maintained by T. Fujisawa.

Japanese version
(including geneal remaks(pdf), posters, and press release note)

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Quantum dots are small conductive regions in a semiconductor, containing a variable number of electrons that ocupy well-defined, discrete quantum states. Quantum dots are often referred to as 'artificial atoms' and provide useful models for studying the behaviour of electrons in atoms, but in a more convenient experimental setting. For example, connecting quantum dots to current and voltage contacts allows their discrete energy spectra to be studied by charge-transport measurements.
Two quantum dots can be connected to form an 'artificial molecule': the strength of the electronic tunneling between the atoms determines whether the 'bonding' is 'ionic' (in which electrons are localized on indivisual dots) or 'covalent' (in which the electrons are delocalized over both dots).
We have seen a transition from ionic to covalent bonding in an artificial molecule that is probed by microwave excitaions, which can be used to vary the inter-dot coupling strength. Of technological relevance is the finding that quantum dots, as single-electron devices, display controllable quantum coherence. A requirement for practical applications of quantum dot circuitry as, for example, logic gates in quantum computers.

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Publication list (incl. some PDF files)

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SEM picture of the quantum dot molecule

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Visit the latest research project.
Single electron dynamics in quantum dots (2000.4 -)

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