On the Feasibility of Quantum Unit Testing

TL;DR

This paper evaluates quantum unit testing methods, comparing classical and quantum-specific tests through extensive empirical analysis, highlighting the superior accuracy and efficiency of quantum-centric tests for verifying quantum software.

Contribution

It introduces and empirically assesses novel quantum-specific unit tests, demonstrating their advantages over traditional statistical approaches in quantum software verification.

Findings

Quantum-centric tests outperform statistical tests in accuracy.

Statevector and Inverse tests reduce false positives and negatives.

Efficient detection of discrepancies with fewer measurements.

Abstract

The increasing complexity of quantum software presents significant challenges for software verification and validation, particularly in the context of unit testing. This work presents a comprehensive study on quantum-centric unit tests, comparing traditional statistical approaches with tests specifically designed for quantum circuits. These include tests that run only on a classical computer, such as the Statevector test, as well as those executable on quantum hardware, such as the Swap test and the novel Inverse test. Through an empirical study and detailed analysis on 1,796,880 mutated quantum circuits, we investigate (a) each test's ability to detect subtle discrepancies between the expected and actual states of a quantum circuit, and (b) the number of measurements required to achieve high reliability. The results demonstrate that quantum-centric tests, particularly the Statevector test and the Inverse test, provide clear advantages in terms of precision and efficiency, reducing both false positives and false negatives compared to statistical tests. This work contributes to the development of more robust and scalable strategies for testing quantum software, supporting the future adoption of fault-tolerant quantum computers and promoting more reliable practices in quantum software engineering.