Design of a fault-tolerant reversible control unit in molecular quantum-dot cellular automata Golnaz Bahadori * , Monireh Houshmand * ,‡ and Mariam Zomorodi-Moghadam † * Department of Electrical Engineering, Imam Reza International University, Mashhad, Iran † Department of Computer Engineering, Ferdowsi University of Mashhad, Mashhad, Iran ‡ m.hooshmand@imamreza.ac.ir Received 2 November 2017 Accepted 17 December 2017 Published 22 January 2018 Quantum-dot cellular automata (QCA) is a promising emerging nanotechnology that has been attracting considerable attention due to its small feature size, ultra-low power consuming, and high clock frequency. Therefore, there have been many e®orts to design computational units based on this technology. Despite these advantages of the QCA-based nanotechnologies, their implementation is susceptible to a high error rate. On the other hand, using the reversible computing leads to zero bit erasures and no energy dissipation. As the reversible computation does not lose information, the fault detection happens with a high probability. In this paper, ¯rst we propose a fault-tolerant control unit using reversible gates which improves on the previous design. The proposed design is then synthesized to the QCA technology and is simulated by the QCADesigner tool. Evaluation results indicate the performance of the proposed approach. Keywords: Quantum-dot cellular automata; reversible computing; fault-tolerant QCA circuit; reversible control unit; fault-tolerant reversible logic. 1. Introduction In the recent decade, the design of integrated circuits has had signi¯cant development in critical features such as reducing transistor size, reducing power consumption, and increasing functionality. However, based on Moore's law for CMOS technology, many fundamental physical limitations have been anticipated and hence, emerging technologies have been considered as alternative computing approaches. In consid- eration of quantum e®ects which can be appeared at nanoscale, quantum-dot cellular automata (QCA) as a promising emerging nanotechnology which works based on quantum e®ects can be an appropriate approach. QCA works based on coulombic interactions which are among adjacent neighboring cells. Coulombic interactions International Journal of Quantum Information Vol. 16, No. 1 (2018) 1850010 (21 pages) # . c World Scienti¯c Publishing Company DOI: 10.1142/S0219749918500107 1850010-1 Int. J. Quantum Inform. Downloaded from www.worldscientific.com by UNIVERSITY OF NEW ENGLAND on 01/28/18. For personal use only.