DEMONSTRATION OF QUANTUM DOTS AND QUANTUM WIRES WITH REMOVABLE IMPURITIES

We present the first demonstration of a nanostructural device with a central electrode (diameter almost-equal-to 300 nm) which is contacted independently. This structure is used to create a quantum wire into which an ''impurity'' of variable size can be introduced. With additional confining gates the structure can also be used to create a quantum dot which can be converted continuously into a quantum ring. Experimental results of magnetoresistance in both low and high magnetic fields are presented which demonstrate the effect of introducing the artificial impurity to a quantum wire.