Although many quantum technologies remain at an early stage of development, they are already prompting questions about the future of nuclear risk reduction and disarmament efforts. On 22 April, under the EU-funded Science and Technology Watchtower project, UNIDIR convened technical and policy experts to discuss the potential impact of quantum sensing, computing and communications in the nuclear domain. The event highlighted the need for multilateral engagement to balance the opportunities and risks posed by quantum technologies.
Participants identified quantum sensing technologies, notably magnetometers and gravimeters, as among the most relevant near-term developments in the nuclear context. Ballistic missile submarines are generally considered highly survivable due to their low detectability. They play a crucial role in strategic deterrence, but advances in quantum sensing could eventually challenge this long-held assumption.
Quantum magnetometers can detect the subtle magnetic disturbances generated by submarines with sensitivity that, in certain configurations, could exceed that of current classical magnetic detection systems. Yet, the field is still relatively underexplored and many anticipated capabilities remain largely theoretical. Current technologies are constrained by hard limits on detection range, particularly in real-world conditions where noise and interference challenges are present. In parallel, detection-evasion techniques continue to evolve alongside advances in detection technologies.
As a stabilizing counterpoint, quantum-assisted navigation could enhance the survivability of sea-based deterrents by enabling submarines to operate for longer periods without surfacing. The overall assessment, however, remains uncertain as evidence based on operational performance remains thin.
Whether quantum advances ultimately have a stabilizing or destabilizing effect on nuclear deterrence will depend heavily on how relevant capabilities evolve and they are pursued by States.
Emerging quantum cyberthreats
Modern digital communications rely heavily on public-key encryption methods. Their security is based on mathematical problems that sufficiently powerful future quantum computers may eventually be able to solve, potentially rendering current protections insufficient. This could create risks for nuclear-related digital systems where information confidentiality, authentication and integrity are essential. For instance, future quantum computers may enable adversaries to compromise the encryption used to secure sensitive nuclear information.
While quantum computers capable of breaking current encryption schemes do not yet exist, there is already concern that adversaries may collect encrypted data today with the intent to decrypt it once the technology matures.
For nuclear systems whose operational data could retain value for decades, the consequences of the so-called “harvest now, decrypt later” attacks can be particularly grave.
Toward quantum-resilient nuclear architectures
In response to quantum cyberthreats, two complementary approaches were identified:
- Post-quantum cryptography (PQC): It is designed to resist both classical and quantum cyberattacks, and can already be deployed on existing systems. A notable example is the set of PQC standards released in 2024 by the US National Institute of Standards and Technology.
- Quantum key distribution (QKD): It is one of the most mature quantum technologies currently available. QKD enables encryption keys to be distributed in a way that makes intrusion attempts detectable.
UNIDIR’s event presented insights from an experimental demonstration conducted by Purdue University on QKD integration within a nuclear reactor control environment. The experiment suggested that QKD could be compatible with latency-sensitive nuclear control architectures and has the potential of addressing the nuclear sector’s stringent confidentiality standards.
Experts highlighted a layered approach combining PQC and QKD, alongside zero-trust architecture and hardware-based security, as a promising direction for strengthening future nuclear system design. However, modernization of nuclear systems is likely to proceed gradually. Their complexity could make rapid cryptographic and infrastructure upgrades difficult, potentially prolonging the window of vulnerability.
Multilateral engagement and the path forward
To date, quantum technologies remain a relatively nascent topic within multilateral nuclear disarmament discussions. Nevertheless, it is important to prepare for potential implications before the relevant technologies mature.
One key issue raised during UNIDIR’s multistakeholder dialogue was that quantum technologies should not be considered in isolation, as their interaction with other emerging technologies – such as AI – could shorten decision-making timelines, increase uncertainty, and elevate the risk of miscalculation during crises. On the positive side, quantum technologies could offer opportunities to strengthen nuclear disarmament efforts through improved verification enabled by quantum sensing and through quantum-secured communications.
The discussion emphasized that awareness among relevant stakeholders must be built to support informed multilateral deliberations.
UNIDIR’s Science and Technology Watchtower project seeks to contribute to such awareness-raising efforts, and this dialogue represented one step forward in bringing the quantum-nuclear nexus onto the disarmament community’s agenda. Previous events under the project’s umbrella have explored issues surrounding additive manufacturing, uncrewed systems, cybersecurity, AI and the Biological Weapons Convention, and more.