Diagnosis of single faults in quantum circuits

TL;DR

This paper presents a method for efficiently detecting and isolating single-gate faults in quantum circuits by leveraging quantum properties, significantly improving fault diagnosis with minimal test cases.

Contribution

It introduces a fault model for quantum circuits that enables complete characterization of single faults and efficient fault detection strategies.

Findings

Most common quantum gates can be isolated without error under the SMGF model

Few test cases are sufficient for fault detection in quantum circuits

Quantum properties enable significant improvements over classical ATPG methods

Abstract

Detecting and isolating faults is crucial for synthesis of quantum circuits. Under the single fault assumption that is now routinely accepted in circuit fault analysis, we show that the behaviour of faulty quantum circuits can be fully characterized by the single faulty gate and the corresponding fault model. This allows us to efficiently determine test input states as well as measurement strategy that can be used to detect every single-gate fault using very few test cases and with minimal probability of error; in fact we demonstrate that most commonly used quantum gates can be isolated without any error under the single missing gate fault (SMGF) model. We crucially exploit the quantum nature of circuits to show vast improvement upon the existing works of automatic test pattern generation (ATPG) for quantum circuits.