Operation of a multi-stage shift register in Quantum-dot Cellular Automata

New bistable single-electron devices, a Quantum-Dot Cellular Automata (QCA) Latch and a two-stage Shift Register were recently demonstrated [1,2]. These devices form a basis for implementing larger scale QCA circuits, where a clock will be used to control the flow of binary information through the circuit. In a multi-stage shift register, a bit is first written into the circuit by the input and then moved along the circuit using each latch as an input to the next. We use a two-stage shift register to replicate the propagation of a single bit through a multi-stage QCA shift register. Experimental data demonstrating single-bit propagation is presented along with a discussion of possible sources of errors. [1] A.O. Orlov, R. K. Kummamuru, R. Ramasubramaniam, G. Toth, C. S. Lent, G. H. Bernstein, and G. L. Snider, Appl. Phys. Lett, 77(2), pp. 295-297 (2001). [2] A.O. Orlov, R. K. Kummamuru, R. Ramasubramaniam, C. S. Lent, G. H. Bernstein, and G. L. Snider, unpublished