Cybersecurity of Cyber-Physical Systems in the Quantum Era: A Systematic Literature Review-Based Approach

The convergence of cyber-physical systems (CPSs), operational technologies (OTs), industrial control systems (ICSs), and quantum computing poses unprecedented challenges for the security and resilience of critical infrastructures (CIs). As quantum capabilities progress, classical cryptographic mechanisms such as RSA and ECC face increasing risks from quantum algorithms (Shor and Grover), while CPS and OT remain constrained by long life cycles, heterogeneity, and limited upgrade capabilities. This study conducts a systematic literature review (SLR) following a GQM-PICO-PRISMA methodological framework to examine 66 primary studies, selected from 1.522 records identified in seven scientific databases and published between 2005 and 2025. The review identifies dominant research domains, ranging from IoT/IIoT security to machine learning-based intrusion detection in CPS/OT environments, and synthesizes key challenges. Findings reveal significant fragmentation in CPS taxonomies, limited integration of post-quantum cryptography (PQC) into OT/ICS protocols, a scarcity of real-world datasets, and insufficient quantum threat modeling (QTM). This work consolidates and structures prior evidence into a literature-derived classification of quantum-era CPS/OT cybersecurity topics and distills a prioritized research agenda for advancing quantum-resilient architectures.