Quantum-dot cellular automata: Review and recent experiments (invited)

An introduction to the operation of quantum-dot cellular automata is presen ted, along with recent experimental results. Quantum-dot cellular automata (QCA) is a transistorless computation paradigm that addresses the issues of device density and interconnection. The basic building blocks of the QCA a rchitecture, such as AND, OR, and NOT are presented. The experimental devic e is a four-dot QCA cell with two electrometers. The dots are metal islands , which are coupled by capacitors and tunnel junctions. An improved design of the cell is presented in which all four dots of the cell are coupled by tunnel junctions. The operation of this basic cell is confirmed by the exte rnally controlled polarization change of the cell. (C) 1999 American Instit ute of Physics. [S0021-8979(99)26608-X].