  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.
