Monday, June 30, 2014

Semiconductor quantum dots with single-atom precision

Nippon Telegraph and Telephone Corp. (NTT; Head Office: Chiyoda-ku, Tokyo; President: Hiroo Unoura), the Paul-Drude-Institute (PDI; Germany), and the Naval Research Laboratory (NRL: USA) have cooperatively developed a novel quantum dot*1 (artificial atom*2) and combined artificial molecules*2 with single-atom precision of the position and configuration. This has been realized at a clean surface of semiconductor single crystal thin film manufactured by Molecular Beam Epitaxy (MBE) *3 by using low-temperature Scanning Tunneling Microscope (STM) *4 to integrate atoms one-by-one with an atom manipulation*5 technique.

Quantum dots are often regarded as artificial atoms because, like real atoms, they confine their electrons to quantized states with discrete energies. But the analogy breaks down quickly, because while real atoms are identical, quantum dots usually comprise hundreds or thousands of atoms - with unavoidable variations in their size and shape and, consequently, in their properties and behavior. External electrostatic gates can be used to reduce these variations. But the more ambitious goal of creating quantum dots with intrinsically perfect fidelity by completely eliminating statistical variations in their size, shape, and arrangement has long remained elusive. Until now.

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