Fault Localization for Broken Control in Quantum Circuits

Reversible circuit is the basis of quantum computation, lowpower COMS, and nanotechnology. To ensure the validity and liability of the reversible circuits, fault detection and fault localization are necessary. And fault localization is more difficult than fault detection. Discussed in this paper is broken control faults (BCFs) localization in reversible circuits. By analyzing the influence of BCFs on the outputs of reversible circuit, it is found that the broken control fault of a gate with size k just changes the outputs of 2\+\n-k\ inputs of the reversible circuit. According to this, the authors presents a method to construct fault localization tree to locate BCFs, which divides the current fault set into several subsets and constructs the sub fault localization tree for each subset recurrently. The method doesn't need any truth table and fault table when constructing the fault localization tree which are necessary for the traditional fault localization method. The height of the fault location tree (FLT) is short and can be used to locate BCFs efficiently. It has less time and space complexity than the BCFs localization methods called Rfault, so it can be applied to larger circuits. This method can also be applied to locate other kinds of fault models, such as missing gate fault.