  Networked-Control Systems (NCSs), a type of cyber-physical systems, consist
of tightly integrated computing, communication and control technologies. While
being very flexible environments, they are vulnerable to computing and
networking attacks. Recent NCSs hacking incidents had major impact. They call
for more research on cyber-physical security. Fears about the use of quantum
computing to break current cryptosystems make matters worse. While the quantum
threat motivated the creation of new disciplines to handle the issue, such as
post-quantum cryptography, other fields have overlooked the existence of
quantum-enabled adversaries. This is the case of cyber-physical defense
research, a distinct but complementary discipline to cyber-physical protection.
Cyber-physical defense refers to the capability to detect and react in response
to cyber-physical attacks. Concretely, it involves the integration of
mechanisms to identify adverse events and prepare response plans, during and
after incidents occur. In this paper, we make the assumption that the
eventually available quantum computer will provide an advantage to adversaries
against defenders, unless they also adopt this technology. We envision the
necessity for a paradigm shift, where an increase of adversarial resources
because of quantum supremacy does not translate into higher likelihood of
disruptions. Consistently with current system design practices in other areas,
such as the use of artificial intelligence for the reinforcement of attack
detection tools, we outline a vision for next generation cyber-physical defense
layers leveraging ideas from quantum computing and machine learning. Through an
example, we show that defenders of NCSs can learn and improve their strategies
to anticipate and recover from attacks.
