Design of an Ultra-Efficient Reversible Full Adder-Subtractor in   Quantum-dot Cellular Automata
  By the progressive scaling of the feature size and power consumption in VLSI chips the part of energy dissipated due to information loss in irreversible computations will become a serious limitation in the near future. Quantum-dot cellular automata (QCA) is an emerging nanotechnology with extremely low energy dissipation which facilitates new computation paradigms such as reversible computing. In this paper a novel reversible full adder-subtractor circuit based on QCA is proposed. Our proposed design is implemented using only one layer and does not require any rotated cells which significantly improves the manufacturability of the design. In addition, it improves the cell count, area and total energy dissipation by almost 45% and 50% and 48%, respectively, as compared to the existing QCA-based single-layer and multilayer reversible full adders. 
Elham Taherkhani, Mohammad Hossein Moaiyeri and Shaahin Angizi
cs.ET