Why quantum, and why now?
Imagine a coordinated attack that denies GNSS access across national infrastructure. The economic impact alone could be devastating - estimates suggest it could cost the UK economy over £1 billion after only 24 hours. In such scenarios, many legacy systems fall back on classical inertial or timing systems, but these often lack the long-term accuracy and robustness to operate effectively in isolation.
Quantum sensors, by contrast, offer the promise of higher precision and longer drift-free operation. Technologies such as cold atom interferometers and optical atomic clocks demonstrate the potential to outperform classical systems. However, to realise their benefits at scale, industry stakeholders must understand not only the potential, but also the integration challenges, some of which are unique to quantum technologies.
To illustrate the promise and complexity of quantum PNT systems, consider a hypothetical airborne navigation platform that integrates Infleqtion's Tiqker optical atomic clock with a quantum accelerometer. This conceptual system offers a resilient, high-accuracy navigation solution, independent of GNSS. It serves as a thought experiment, an exploration of how cold atom technology might translate from laboratory prototypes to mission-critical applications.
Benchmarking quantum and classical systems
Comparing the performance of quantum and classical systems is not straightforward, especially in complex missions like our hypothetical airborne platform. In this scenario, Infleqtion’s Tiqker optical atomic clock provides frequency stabilities rivalling the best classical systems, with an Allan deviation flicker floor of <5x10-15, (effectively timing error) over long durations. To meaningfully validate such figures across platforms, however, robust benchmarking is essential. This may also include advanced time-transfer technologies with femtosecond resolution, which are still under development (Hugo Bergeronet al. (2019), Xiao Xiang et al. (2023)).
In airborne deployments, where integration might involve fusing outputs from multiple atomic clocks, verifying a coherent and reliable metric introduces additional complexity. For example, clock outputs may drift in subtly different ways depending on environmental conditions or vibration profiles. System designers might pre-emptively calibrate individual clocks against a reference or apply sensor fusion algorithms to harmonise outputs. Yet these mitigations cannot fully resolve divergence during dynamic flight conditions, where real-time validation of timing integrity becomes difficult. Even as a thought experiment, this illustrates how airborne quantum PNT requires not only precise components but also sophisticated coordination and monitoring strategies.
Verification and validation in a probabilistic world
Quantum systems are fundamentally probabilistic. For an airborne platform operating independently of GNSS, this raises a critical question: how do you confirm performance within stochastic bounds when real-time data integrity is essential? Traditional validation methods may not suffice. Instead, integration teams may require sophisticated stochastic modelling and simulation frameworks that reflect edge cases, such as turbulence, variable flight dynamics, or electromagnetic interference.
As highlighted in recent IET articles, probabilistic validation is not a peripheral concern; it is central to real-world deployment. Successful navigation in this context demands new thinking about performance assurance.
Quantum fragility and environmental interference
Quantum states are delicate, and airborne environments would likely amplify that fragility. System designers can and do mitigate many risks through techniques such as magnetic shielding, active thermal regulation, and vibration isolation. For example, a quantum accelerometer might be mounted on a damped platform and enclosed in a mu-metal shield to suppress environmental interference.
Yet these strategies cannot eliminate all sources of noise. Rapidly changing electromagnetic fields from other avionics systems or subtle cabin pressure fluctuations in high-altitude flight can still affect quantum coherence in ways that are hard to fully predict or filter in real time. In our conceptual scenario, such residual effects would remain a key design consideration, requiring both compensation techniques and robust error models to maintain reliable performance.
Without such precautions, even a high-precision system could deliver misleading data, which is an unacceptable risk for critical navigation.
Redundancy and failure modes
System integrators routinely build in redundancy. However, in our thought experiment, the failure modes do not always resemble those seen in classical systems. One challenge would be ensuring that sensors continue to operate within acceptable performance envelopes without frequent recalibration, a non-trivial problem in a probabilistic domain.
Maintaining confidence in system health may call for new monitoring techniques, ones that infer internal states indirectly or incorporate feedback from supporting classical systems. In high-reliability environments, such as aerospace, this added complexity reinforces the need for a systems engineering approach that deeply understands quantum behaviour.
Contextual quantum sensor integration is key
Perhaps the biggest challenge for integrators is that quantum sensor integration is highly context-dependent. A solution suited to airborne platforms may not be viable for maritime or land-based systems. Each environment brings unique constraints, including vibration, thermal load, and magnetic interference. Size, weight, power, and cost (SWaP-C) also vary widely between applications; a naval vessel can accommodate a container-scale sensor, while an unmanned aerial system cannot.
In defence contexts, this becomes even more complex. Mission-specific quantum sensor designs can trigger higher classification levels, limiting collaboration and slowing deployment. Navigating these technical, regulatory, and security constraints requires strategic planning as much as technical insight.
Case study: Infleqtion’s approach
Fortunately, suppliers are meeting these challenges directly; such as Infleqtion. Infleqtion are a leading ‘quantum information company’ who provide platforms utilising cold-atom technology along three key themes: quantum computers, optical atomic clocks and quantum sensors. With offices in the United States, United Kingdom, and Australia, they have key developments underway on PNT systems in partnership with government and industry. Ryan Hanley from Infleqtion has provided context for how they tackled the above challenges:
“Infleqtion is advancing quantum PNT sensors from the laboratory to real-world deployment by pairing world-class cold atom expertise with a system-level approach to integration. We design our quantum systems around real-world constraints—such as SWaP-C, environmental robustness, and mission-specific requirements—building modular, application-driven platforms that complement classical systems and enable seamless integration.
Each product is engineered with the end-use case in mind, from airborne to maritime platforms, allowing us to tailor interface specifications for GNSS-denied PNT operations and ensure performance in diverse conditions.
Infleqtion leads in developing deployable quantum technologies. Our work includes deploying cold atom PNT systems on airborne and maritime platforms, delivering a world-leading neutral atom quantum computer for the UK, and contributing to the production of Bose-Einstein condensates aboard the International Space Station. Field trials, together with deep collaboration with partners like QinetiQ and BAE Systems, have enabled us to validate performance, understand integration challenges such as failure modes, performance limits, and environmental constraints, and mature our technology stack for mission-critical use in defence and commercial markets.”
Ryan Hanley, Head of Research and Development, UK at Infleqtion
TTP: bridging science and deployment
At TTP, we work alongside system integrators to bridge the gap between emerging quantum technologies and practical, deployable systems. We support clients in evaluating quantum sensor options, capturing requirements, and developing systems that make the best use of this new capability.
Whether you are building a proof of concept or preparing for deployment, we help ensure your architecture makes the most of quantum without being derailed by avoidable integration challenges.
Looking ahead: resilient PNT in a quantum era
Quantum sensors offer a transformative path to resilient, GNSS-independent navigation. Their unparalleled sensitivity and long-term stability could redefine what is possible in PNT.
However, unlocking that potential requires more than scientific expertise. It demands engineering foresight, thoughtful integration, and a clear understanding of the operational context.
Companies such as Infleqtion are rising to the challenge, and TTP is here to help integrators navigate the complexities of deployment. The road to quantum-ready PNT may be complex, but it is essential. In a world where GNSS denial is increasingly plausible, resilience is no longer a luxury; it is a necessity.
