Spin polarized injection into a quantum dot by means of the spatial separation of spins

We describe transport measurements on a small lateral dot involving spin polarized injection and detection. The novel layout of the lateral dot allows its electron occupation number to be reduced to 0 from 60 while maintaining operating tunneling barriers. The spin polarized injection occurs above View the MathML source due to the presence of spin resolved edge states in the two dimensional electron gas which form the leads to the quantum dot. We demonstrate the consequences of spin polarized leads by focusing on two spin properties of the quantum dot close to filling factor, ν, 2. Firstly, we illustrate an alternating odd/even occupation number effect due to spin blockade through current readout at ν=2. Secondly, we detect spin transitions directly at fixed electron number in the quantum dot as the magnetic field is lowered away from ν=2. The experimental results are explained by a comparison to theoretical calculations of the ground states in the different regimes. The current readout process is one of the requirements of a quantum dot based spin qubit quantum computer.