For cyber-physical systems (CPS), ensuring process and data security is critically important since the corresponding infrastructure needs to have high operational efficiency with no downtime. There are many techniques available that make communications in CPS environments secure – such as enabling traffic encryption between sensors and the computers processing the sensor’s data, incorporating message authentication codes to achieve integrity, etc. However, most of these techniques are dependent on some form of symmetric or asymmetric cryptographic algorithms like AES and RSA. These algorithms are under threat because of the emerging quantum computing paradigm: with quantum computing, these encryption algorithms can be potentially broken. It is therefore desirable to explore the use of quantum cryptography – which cannot be broken by quantum computing – for securing the classical communications infrastructure deployed in CPS. In this paper, we discuss possible consequences of this option. We also explain how quantum computers can help even more: namely, they can be used to maximize the system’s security where scalability is never a constraint, and to ensure we are not wasting time cycles on communicating and processing irrelevant information.