05 (2010 Selected)：

Manipulation of electron spin and nuclear spins in hetero-g-factor double quantum dot

We aim the manipulation of electron and nuclear spins in semiconductor quantum dots using the spin-dependent single electron transport, the spin block ade, as a sensitive prove for spin scattering events in quantum dots.
We use a coupled double quantum dot made of different materials for each dot. Electron g factor of the dots are largely different each other. We will study the spin blockade effect and the lifting of the spin blockade due to electron spin - nuclear spin scattering. Polarized nuclear spins in quantum dot can be a future long-lived quantum memory for electron spin qubit.

We will fabricate double quantum dot devices made of GaAs dot and InGaAs dot, characterizing the g-factors of each dot, and measure the leakage current of the device in the spin blockade region. Repeating electron nuclear spin scattering at certain condition in spin blockade state, can polarize nuclear spins in the dot. AC magnetic field with RF frequency is applied to the device in order to coherently manipulate the polarized nuclear spins by means of NMR technique. A difference of quadruple splitting for the GaAs and InGaAs dot can be used individually access and manipulate the nuclear spins for each dot. We also use a fast DC pulse with nano second order, a typical time scale for the single electron tunneling interval in the device, in order to study a fast dynamics of the polarized nuclear spins. We will also use more complex multi step DC pulse and find the optimum sequence for writing/reading the nuclear spin memory.

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