Quantum technologies are often discussed in terms of being “revolutionary.” In the long term, this may likely be true, but at present, at least in military contexts, perhaps a more useful framing is to ask: in what domains and ways do quantum capabilities demonstrably outperform contemporary classical approaches; where are such technologies still insufficiently mature in readiness and operational feasibility; and what effects do such technologies exert on force design, intelligence tradecraft, and risks to national security? As Dr. Andrew Ilachinski of the Center for Naval Analysis has recently noted, at present the answer is uneven across (1) computing, (2) sensing, and (3) communications/transmission; with net impacts that are real, but frequently mischaracterized.
Quantum Computing: Real Capability — and Limits
Current quantum systems remain in the “noisy, intermediate-scale” era; they are useful primarily as research platforms and, selectively, as co-processors when paired with high-performance computing architectures. The near-term value for defense operations is not a Hollywood version of “break all cryptography,” but more realistically, the capability to achieve advantages in key problem spaces, including quantum simulation for materials and chemistry (propellants, catalysts, corrosion, batteries), certain optimization/graph problems under narrow constraints, and exploratory methods of machine learning and artificial intelligence (AI). The Congressional Research Service (CRS) reports that quantum computers are “in a relatively early stage of development” such that practical applications are dependent upon reducing error rates, and improving algorithms, software, and hardware.
Militarily, quantum advantage largely hinges on fault-tolerant quantum computing, which requires robust error correction. The CRS report highlights the relative fragility of quantum states and the difficulty of sustaining them in real environments. Critically, qubit counts alone are a misleading metric; the ability to process “more qubits” is meaningless, if these quantum parcels of information are noisy, and therefore do not equate to mission-relevant computational capability and/or effectiveness.
One of the more strategically salient claims about quantum computing is its potential to break widely used cryptography systems once sufficiently large fault-tolerant (quantum) operations. The CRS report summarizes current estimates that breaking existing encryption paradigms would require approximately 20 million qubits. Cashing the reality check reveals that “the most advanced quantum computers today generally have no more than around 1,000 qubits.” Even if the precise number of currently viable qubit capability is imprecise and conservative, the order of magnitude gap is nevertheless enormous. Clearly, presently viable and near-term quantum computers are not at a level that would enable their use, and risk as decryption devices. However, the threat is still operationally relevant because of assimilate-now, decrypt-later approaches to strategically latent engagements. Indeed, the CRS report explicitly warns that information intercepted prior to deploying post-quantum cryptography would likely not be protected and thus would present vulnerabilities to subsequent attack.
Quantum Sensing: Most Mature Defense Relevance
Quantum sensing has been widely assessed to be the most mature domain for defense applications. In this light, the CRS report support conclusions of the Defense Science Board (DSB) that quantum sensing is currently “poised for mission use,” with positioning, navigation, and timing (PNT) alternatives for advanced intelligence, surveillance and reconnaissance (ISR) modalities; including detection of underground structures, or nuclear materials (viz., via sensitivity to environmental disturbances), and more precise detection of electromagnetic emissions with implications for identifying concealed, clandestine and/or covert forces and electromagnetic engagement(s). Writ large, this creates new, more capable tools for use in contested environments where global positioning systems (GPS) may be jammed and/or deluded and where the highly enhanced acuity of quantum sensing can enable new regimes of target detection and discernment.
Yet, although claims of decisive anti-stealth capability (i.e., “quantum radar” narratives) persist, the CRS report sustains the DSB conclusion that quantum radar “will not provide upgraded capability” that is viable for near-term use in/by the Department of War (DoW). This is a cautionary assertion: quantum science and technology are not magic; so while certain applications are valid and show promise for near-term utility, others fail rigorous engineering and operational analyses and are not yet ready for “prime time” operational employment. Any genuine attempt at operational planning should be mindful of what (even the most promising) disruptive technology actually can, and/or cannot do in real world settings as relevant to the military and national defense mission.
To wit, even in those situations where quantum sensing is mature, deployment constraints (e.g., of size/weight/power, environmental controls for certain modalities, calibration burdens, and integration into existing platforms and networks without trading away reliability) are real and pose genuine limitations. So while the opportunities afforded by quantum sensing are substantial, it is important to bear in mind that what is feasible is not always fieldable, and what makes something unique does not render it to be directly usable.
Quantum Transmission and Communications: Promising, but Still Problematic
As detailed in the CRS report, it is critical to discern (somewhat incipient) broad scale “quantum communications” from (more developed but still relatively nascent) quantum key distribution (QKD) systems and functions. Theoretically, quantum communications could securely yoke quantum sensors and computers within a networked array to extend robustness at range; but such network designs are still rather basic.
The predominant advantage of using QKD systems is to detect eavesdropping during signal transmission. Still, QKD systems are not without vulnerabilities and limitations. QKD transmissions can be intercepted at relay stations currently required for long-distance links. Furthermore, the DSB concluded that while China has invested heavily in QKD, and built (QKD) supportive infrastructure, operationally, QKD “has not been implemented with sufficient capability or security to be deployed for [military] use.” Hence, for the DoD, QKD would be best regarded as a niche tool with select capabilities within specific threat models, modes and architectures, and not a general replacement for modern cryptography, nor a substitute for hardening cryptographic/computational endpoints in command, supply chain, or overall communications’ security.
Net Impact on Defense Science and Technology
In conclusion, in my view quantum is best regarded as a force enabling technology that fortifies:
• Navigation in contested areas through employment of quantum clocks and sensing.
• ISR and EW through quantum sensing-optimized receptivity to electromagnetic fields, timing, and subtle environmental signatures.
• Materials, energetics, and platform sustainment through quantum computing-based simulations.
• AI co-design through hybrid architectures in which quantum components accelerate specific (classical) computational kernels and capacities.
Realistic assessment and acknowledgement of these capacities and applications are important for doctrine and governance, as DoW engagement and oversight of quantum technology becomes a increasingly incentivized. For example, the (January) 2026 DoW Inspector General management advisory reported some ambiguity in assurance that quantum computing capabilities were prioritized in ways that could be most beneficial to DoW; citing (1) failures to maintain required annual updates of near-term capabilities’ and problems’ lists, and (2) internal consensus that demonstrable quantum capability is still 10-15 years away. This should not serve as a condemnation of quantum possibilities and/or investments; rather, it should be taken as a sober perspective upon the need for realistic assessment, proper focus, metrics of progress, and accountability.
Next Week: Part Two: Quantum Technology — Recognizing Risks and Threats to National Security and Defense
Disclaimer
The views and opinions expressed in this essay are those of the authors and do not necessarily reflect those of the United States government, Department of War or the National Defense University.
Dr. James Giordano is Director of the Center for Disruptive Technology and Future Warfare of the Institute for National Strategic Studies at the National Defense University.