Fault Models in Reversible and Quantum Circuits

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Advances in Unconventional Computing

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In this chapter we describe faults that can occur in reversible circuit as compared to faults that can occur in classical irreversible circuits. Because there are many approaches from classical irreversible circuits that are being adapted to reversible circuits, it is necessary to analyze what faults that exists in irreversible circuits can appear in reversible circuit as well. Thus we focus on comparing faults that can appear in classical circuit technology with faults that can appear in reversible and quantum circuit technology. The comparison is done from the point of view of information reversible and information irreversible circuit technologies. We show that the impact of reversible computing and quantum technology strongly modifies the fault types that can appear and thus the fault models that should be considered. Unlike in the classical non-reversible transistor based circuits, in reversible circuits it is necessary to specify what type of implementation technology is used as different technologies can be affected by different faults. Moreover the level of faults and their analysis must be revised to precisely capture the effects and properties of quantum gates and quantum circuits that share several similarities with reversible circuits. By not doing so the available testing approaches adapted from classical circuits would not be able to properly detect relevant faults. In addition, if the classical faults are directly applied without revision and modifications, the presented testing procedure would be testing for such faults that cannot physically occur in the given implementation of reversible circuits. The observation and analysis of these various faults presented in this chapter clearly demonstrates what faults can occur and what faults cannot occur in various reversible technologies. Consequently the results from this chapter can be used to design more precise tests for reversible logic circuits. Moreover the clearly described differences between faults occurring in reversible and irreversible circuits means that new algorithms for fault detection should be implemented specifically for particular reversible technologies.


Part of the Emergence, Complexity and Computation book series (ECC, volume 22)