Updated April 5, 2022
Defense Primer: Quantum Technology
Quantum technology translates the principles of quantum
militaries to continue to operate at full performance in GPS-
physics into technological applications. In general, quantum
degraded or GPS-denied environments.
technology has not yet reached maturity; however, it could
In addition, quantum sensors could potentially be used in an
hold significant implications for the future of military
intelligence, surveillance, and reconnaissance (ISR) role.
sensing, encryption, and communications, as well as for
Successful development and deployment of such sensors
congressional oversight, authorizations, and appropriations.
could lead to significant improvements in submarine
Key Concepts in Quantum Technology
detection and, in turn, compromise the survivability of sea-
based nuclear deterrents. Quantum sensors could also
Quantum applications rely on a number of key concepts,
enable military personnel to detect underground structures
including superposition, quantum bits (qubits), and
or nuclear materials due to their expected “extreme
entanglement. Superposition refers to the ability of quantum
sensitivity to environmental disturbances.” The sensitivity
systems to exist in two or more states simultaneously. A
of quantum sensors could similarly potentially enable
qubit is a computing unit that leverages the principle of
militaries to detect electromagnetic emissions, thus
superposition to encode information. (A classical computer
enhancing electronic warfare capabilities and potentially
encodes information in bits that can represent binary states
assisting in locating concealed adversary forces.
of either 0 or 1, whereas a quantum computer encodes
information in qubits, each of which can represent 0, 1, or a
Quantum Computers
combination of 0 and 1 at the same time. Thus, the power of
According to NAS, “quantum computers are the only
a quantum computer increases exponentially with the
known model for computing that could offer exponential
addition of each qubit.)
speedup over today’s computers.” While quantum
Entanglement is defined by the National Academy of
computers are in a relatively early stage of development,
Sciences (NAS) as a property in which “two or more
advances—many of which are driven by the commercial
quantum objects in a system can be intrinsically linked such
sector—could hold implications for the future of artificial
that measurement of one dictates the possible measurement
intelligence (AI), encryption, and other disciplines.
outcomes for another, regardless of how far apart the two
objects are.”
For example, some analysts have suggested that quantum
Entanglement underpins a number of potential
computers could enable advances in machine learning, a
military applications of quantum technology. Both
subfield of AI. Such advances could spur improved pattern
superposition and entanglement are, however, difficult to
recognition and machine-based target identification. This
sustain due to the fragility of quantum states, which can be
could in turn enable the development of more accurate
disrupted by minute movements, changes in temperature, or
lethal autonomous weapon systems, or weapons capable of
other environmental factors.
selecting and engaging targets without the need for manual
Military Applications of
human control or remote operation. AI-enabled quantum
Quantum Technology
computers potentially could be paired with quantum sensors
to further enhance military ISR applications.
The Defense Science Board (DSB), an independent
Department of Defense (DOD) board of scientific advisors,
In addition, quantum computers could potentially decrypt
has concluded that three applications of quantum
classified or controlled unclassified information stored on
technology hold the most promise for DOD: quantum
encrypted media, allowing adversaries to gain access to
sensing, quantum computers, and quantum
sensitive information about U.S. military or intelligence
communications. The DSB concluded that quantum radar,
operations. Some analysts note that significant advances in
hypothesized to be capable of identifying the performance
quantum computing would likely be required to break
characteristics (e.g., radar cross-section, speed) of objects—
current encryption methods. Their estimates suggest that a
including low observable, or stealth, aircraft—“will not
quantum computer with around 20 million qubits would be
provide upgraded capability to DOD.”
required to break current encryption methods; however, the
most advanced quantum computers today generally have no
Quantum Sensing
more than 256 qubits.
Quantum sensing uses the principles of quantum physics
within a sensor. According to the DSB, this is the most
The practical applications of quantum computers will likely
mature military application of quantum technologies and is
be realized only after improvement in error rates and
currently “poised for mission use.” Quantum sensing could
development of new quantum algorithms, software tools,
provide a number of enhanced military capabilities. For
and hardware. While, as NAS notes, “there is no guarantee
example, it could provide alternative positioning,
that [these technical challenges] will be overcome,” some
navigation, and timing options that could in theory allow
analysts believe that an initial quantum computer prototype
capable of breaking current encryption methods could be
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Defense Primer: Quantum Technology
developed in the 2030 to 2040 timeframe. For this reason,
potentially address within the next one to three years. The
NAS concludes that “the development, standardization, and
list currently includes quantum chemistry, optimization, and
deployment of post-quantum cryptography is critical for
machine learning. Section 214 also directs the services to
minimizing the chance of a potential security and privacy
establish programs with small and medium businesses to
disaster.” (Information intercepted prior to the deployment
provide quantum computing capabilities to government,
of post-quantum cryptography would not be protected.)
industry, and academic researchers working on these
challenges. Section 1722 directs DOD to conduct an
Quantum Communications
assessment of the risks posed by quantum computers, as
Quantum communications—excluding quantum key
well as current standards for post-quantum cryptography.
distribution ([QKD], discussed below)—are in a nascent
Finally, Section 105 of the FY2022 NDAA (P.L. 117-81)
stage of development. Quantum communications could
directs the President to establish—through the National
theoretically enable the secure networking of quantum
Science and Technology Council—the Subcommittee on
military sensors, computers, and other systems, thus
the Economic and Security Implications of Quantum
improving performance over that of a single quantum
Information Science, while Section 229 directs the
system or classical communications network. Networking
Secretary of Defense to “establish a set of activities to
could additionally strengthen the robustness of such
accelerate the development and deployment of dual-use
systems at range, thus expanding the potential environments
quantum capabilities.”
in which they could be deployed (i.e., outside of the
laboratory settings generally required to sustain fragile
DOD has not provided a breakdown of quantum research in
quantum states). This could significantly expand the
recent budget requests; however, according to data analytics
military utility of quantum communications.
firm Govini, DOD requested approximately $688M for
Quantum key distribution is a subset of quantum
quantum technologies and research in FY2021.
communications that uses the principles of quantum physics
to encrypt information that is then sent over classical
Potential Questions for Congress
networks. QKD enables secure communications that cannot
What funding level does the current maturity of military
be covertly intercepted during transmission. (QKD
applications of quantum technology warrant? To what
communications can, however, be intercepted at the relay
extent, if at all, should the U.S. government invest in
stations currently required for long-distance transmissions.)
and research technologies that enable quantum military
China is reportedly investing heavily in QKD and
applications (e.g., materials science, fabrication
completed construction of an approximately 1,250 mile
techniques)?
Beijing-Shanghai quantum network in 2016. Nonetheless,
To what extent, if at all, can commercial advances in
the DSB concluded that “QKD has not been implemented
quantum technology be leveraged for military
with sufficient capability or security to be deployed for
applications?
DOD mission use.”
How mature are U.S. competitor efforts to develop
military applications of quantum technologies? To what
Funding and Recent Legislative Activity
extent, if at all, could such efforts threaten advanced
Congress has considered the management and implications
U.S. military capabilities, such as submarines and
of quantum technology. For example, Section 234 of the
stealth aircraft?
FY2019 National Defense Authorization Act (NDAA) (P.L.
What measures are being taken to develop quantum-
115-232) directs the Secretary of Defense—acting through
resistant encryption and to protect data that have been
the Under Secretary of Defense for Research and
encrypted using current methods?
Engineering—to execute a quantum technology research
What measures, if any, should the United States take to
and development program in coordination with the private
ensure that the quantum workforce is sufficient to
sector and other government agencies.
support U.S. competitiveness in quantum technology?
Furthermore, Section 220 of the FY2020 NDAA (P.L. 116-
Related CRS Products
92) requires DOD to develop ethics guidelines for the use
CRS Report R45409, Quantum Information Science: Applications,
of quantum technologies, as well as plans for supporting the
Global Research and Development, and Policy Considerations, by
quantum workforce and reducing the cybersecurity risks
Patricia Moloney Figliola.
associated with quantum technologies. It additionally
authorizes the Secretary of each military department to
establish Quantum Information Science (QIS) Research
Other Resources
Centers that may “engage with appropriate public and
Defense Science Board, Applications of Quantum Technologies:
private sector organizations” to advance quantum research.
Executive Summary, October 2019.
To date, the Navy has designated the Naval Research
Emily Grumbling and Mark Horowitz, eds., Quantum
Laboratory as its QIS Research Center, while the Air Force
Computing: Progress and Prospects, National Academy of
has designated the Air Force Research Laboratory as a QIS
Sciences, 2019.
Research Center for both the Air Force and Space Force.
The Army says it does not plan to establish a QIS Research
Center at this time.
Kelley M. Sayler, Analyst in Advanced Technology and
Section 214 of the FY2021 NDAA (P.L. 116-283) directs
Global Security
the services to compile and annually update a list of
technical challenges that quantum computers could
IF11836
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Defense Primer: Quantum Technology
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