Quantum-inspired algorithm for direct multi-class classification

Roberto Giuntini, Federico Holik, Daniel K. Park, Hector Freytes, Carsten Blank, Giuseppe Sergioli

Research output: Contribution to journalArticlepeer-review


Over the last few decades, quantum machine learning has emerged as a groundbreaking discipline. Harnessing the peculiarities of quantum computation for machine learning tasks offers promising advantages. Quantum-inspired machine learning has revealed how relevant benefits for machine learning problems can be obtained using the quantum information theory even without employing quantum computers. In the recent past, experiments have demonstrated how to design an algorithm for binary classification inspired by the method of quantum state discrimination, which exhibits high performance with respect to several standard classifiers. However, a generalization of this quantum-inspired binary classifier to a multi-class scenario remains nontrivial. Typically, a simple solution in machine learning decomposes multi-class classification into a combinatorial number of binary classifications, with a concomitant increase in computational resources. In this study, we introduce a quantum-inspired classifier that avoids this problem. Inspired by quantum state discrimination, our classifier performs multi-class classification directly without using binary classifiers. We first compared the performance of the quantum-inspired multi-class classifier with eleven standard classifiers. The comparison revealed an excellent performance of the quantum-inspired classifier. Comparing these results with those obtained using the decomposition in binary classifiers shows that our method improves the accuracy and reduces the time complexity. Therefore, the quantum-inspired machine learning algorithm proposed in this work is an effective and efficient framework for multi-class classification. Finally, although these advantages can be attained without employing any quantum component in the hardware, we discuss how it is possible to implement the model in quantum hardware.

Original languageEnglish
Article number109956
JournalApplied Soft Computing
Publication statusPublished - 2023 Feb

Bibliographical note

Funding Information:
R.G. and G.S. acknowledge the support from the Italian Ministry of Education , PRIN project (Grant No. 20173YP4N3 ) and the FdS (Fondazione di Sardegna) project (cup: F73C22001360007 ). D.K.P. acknowledges the support from the National Research Foundation of Korea (Grant No. 2019M3E4A1079666 , 2021M3H3A1038085 , 2022M3E4A1074591 ). F.H. acknowledges the support from the Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación (Grant No. PICT- 2019-2019-01272 ). We thank Keng Loon Chow for his valuable suggestions during the conceptualization of this study. All authors reviewed the manuscript.

Publisher Copyright:
© 2022 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Software


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