MICHAEL J. BIERCUK AND RICHARD FONTAINE
China recently announced the launch of its Jinan Project, a quantum information effort billed as “the world’s first unhackable computer network.” Building on its launch last year of the world’s first quantum-enabled satellite, China has made significant strides in quantum technology, a field with rapidly increasing relevance to national security. Its satellite has been hailed as a major step toward “unbreakable” encrypted communications.
China is far from the only country interested in quantum technology and its potential applications to national security. Beyond secure communications, quantum computing offers new ways of modelling chemical processes, as well as superior (and artificial intelligence-empowered) targeting and autonomous decision-making systems. Quantum computers may provide the ability to crack existing secure communications, by attacking the security of public key cryptosystems. And they may even augment the performance of “standoff detection” in military settings, in which targets with magnetic or gravitational signatures are detected at a distance, and without contact with the threats themselves.
In truth, however, the full promise of quantum technology is unknown, in national security or any other field. While major claims on the subject sometimes reflect hype more than reality, it’s incontrovertible that governments and companies around the world are investing in it in a serious way. The United States has directed significant defense and intelligence dollars into quantum research. The European Union is devoting over a billion euros to its own quantum technology ecosystem. And it appears Russia may be making quiet investments as well.
The bets are good ones. Given the state of the field and its vast potential, quantum technology could be transformational, possibly even as significant an advance in the 21st century as harnessing electricity was in the 19th.
Yet the field remains very poorly understood outside of specialist circles, and popular accounts often tend toward misunderstandings and misleading claims. National security experts who are otherwise comfortable discussing nuclear weapons design, cybersecurity, energy and tech issues tend to look blankly at the idea of quantum technology or rely on hyperbolic media reports.
This may be forgivable given the technical complexity of the field and the phenomena that run counter to our daily experience. Yet this deficit puts the quality of America’s strategic planning and investment efforts at risk. And inaction following several of the U.S. government’s major strategic planning documents may open the door to other nations overtaking America’s historical strategic advantage in the field.
It’s time for this to change. Given the range of possible national security applications, and the fervor with which America’s friends and competitors are pursuing advances, the country’s strategic elite need to understand the basics. In that light, this article — a quantum primer of sorts — is co-authored by a university-based quantum scientist and a decidedly non-specialist national security analyst. While we have very different backgrounds and areas of expertise, we are united by an interest in the possibilities inherent in quantum technology and ensuring that the United States harnesses that potential with wisdom.
For the reader who has made it thus far, we’d ask: Put aside for a moment the hype, the grandiose claims, the self-interested sales pitches, and the science fiction-esque quality of the discussion as it often takes shape. The truth of quantum technologies is more interesting still.
Back to Basics
Quantum physics is, simply put, the set of laws that governs the universe on tiny scales. We mean really, really small — distances measured in nanometers, or mere billionths of a meter. Those laws appear completely different than the so-called “classical” physics of electromagnetism, gravity, and mechanics, which govern our daily experience. In our classical world, actions are deterministic. A rocket follows a predictable path, and a car slows predictably, given well-known physical laws. At the tiny, quantum level, however, things get weird. In essence, the predictable view of the world breaks down, and in its place are new rules that seem counterintuitive at best and completely at odds with reality at worst.
Most modern technology already leverages quantum physics. The trillion-dollar semiconductor industry, which has given us powerful microprocessors and mobile telephony, owes its existence to the quantum behavior of electrons in solids. In practice, semiconductors wash away most of the exotic phenomena observed at the quantum level, by aggregating many individual particles and then relying on bulk properties averaged across them. Quantum technology, by contrast, exploits those phenomena, by accessing and controlling individual atoms, electrons in circuits, and photons.
Despite countless schoolbook diagrams, atoms are not, in fact, very much like a mini cartoon solar system, with electrons orbiting their nucleus in defined pathways. Instead, tiny particles behave more like waves than spheres, and they can spread out across space and interfere with one another like ripples in a pond. This has a counterintuitive implication: We can only consider the behavior of matter at the quantum level probabilistically, rather than as fixed absolutes. At the human level, of course, we don’t observe this; the computer or phone on which you are reading this article exists in only one place, and if you fling it out of the window, its motion can be accurately predicted using the laws of mechanics.
It is this probabilistic, wave-like nature of light and matter that explains some of the stranger things we observe in quantum physics. Instead of being described as existing here or there, as with a baseball, a book or a B-2, quantum systems may be (loosely) described as simultaneously existing in more than one place until the system is observed (to say it more generally, these systems can exist in more than one “quantum state” at the same time).
This effect is known as “superposition,” and seems crazy enough on its own. But it gets stranger. Upon observation, the quantum system “chooses” just one possibility, and the superposition collapses. In other words, a particle of light or matter can be described as being in multiple places at the same time, until you have a look at it; then it freezes in just one place.
Quantum systems may also be linked together in a way that classical physics cannot describe. With “entanglement,” linked particles can be “remotely controlled” no matter how far apart they may be. Manipulate the local partner of an entangled pair and you instantaneously manipulate its entangled partner as well. In many circumstances our vernacular language — tied to our own physical experiences — is simply inadequate to describe the physics we find in the quantum realm.
These effects are so counter-intuitive that for decades many of the 20th century’s greatest scientific minds dismissed them as nothing more than mathematical oddities. Beginning in the 1980s, however, scientists began to isolate quantum systems in the laboratory and demonstrate that this unusual physics was in fact real. Now, researchers are seeking to employ those systems to power a new generation of applications — the so-called second quantum revolution. And the race is on, across the world, to make the greatest and fastest strides.
New Technologies, New Applications
You probably don’t realize it, but you very likely already employ quantum technology on a regular basis. Get in your car, switch on Waze or Google Maps, and you are already harnessing quantum effects. A GPS receiver works by measuring the tiny time delays in signals from multiple satellites separated in space. Doing this requires very stable and very accurate time measurement: enter the atomic clock. Such clocks, which reside inside every GPS satellite, often use quantum superposition. They employ atoms of Cesium or Rubidium to achieve an extremely stable “tick,” one accessible only within the atoms themselves. The primary standard for time, operated using this kind of physics, is so stable that it will lose just one second in 100 million years. That kind of stability powers not just GPS but other systems as well, including the synchronization protocols that govern Internet operations.
A clock that loses just a second in 100 million years may sound like more than we need, but scientists are hoping to harness quantum technology to do even better. New generations of research grade clocks based on single atoms are currently in development that will lose only a second in a billion years. This kind of stability enables clocks to be used as sensors — their tick is so regular that tiny changes in the environment due to gravity, magnetic fields, and the like produce identifiable signatures. The most sensitive experiments to date have shown that such clocks can measure the change in the Earth’s gravity that comes from lifting the clock by a bit more than one foot. Atomic sensors are already in use for military applications, but improvements in measurement sensitivity to these extraordinary scales promise to dramatically improve their capabilities and enable an entire new generation of remote sensors.
Today, most attention is focused not on perfecting clocks but rather on the esoteric-sounding realm of quantum information. The field consists of both quantum communications (think super-secure) and quantum computation (think blazingly fast).
Quantum communications seeks to enable new cryptographic protocols, using the rules of quantum physics to guarantee security. Photons, or particles of light which are widely used today in optical communications, possess a variety of physical properties that obey the rules of quantum mechanics. In quantum communications, researchers typically leverage the feature we discussed earlier — that measuring or “observing” a quantum state destroys its superposition or entanglement. This measurement-means-destruction phenomenon provides a new tool to detect hacking: code your quantum message in the right way and an attempt to intercept your information will destroy it — and do so in a detectable way.
Today, quantum data transfer rates remain quite low, and so communicating entire messages is not yet practical. Instead, experts have focused primarily on quantum cryptographic key distribution (sometimes called QKD) — the way in which two parties use quantum communications to share a “classical” cipher used for encoding and decoding their message. But each of these efforts does not ensure “unhackable” communications or perfectly detectable eavesdropping, only security improvements. At the moment, exploring the variety of security attacks on quantum communications systems is an active area of research.
Quantum computers in general rely on quantum bits (qubits) — their version of the bits (binary digits) that power classical computers. Bits are as straightforward as it gets. They take discrete values of 1 and 0, and they are represented physically as electronic transistors that switch on or off. Classical computers use the zeros and ones to encode information; to represent the number 18, for instance, a computer uses “00010010.”
Qubits, by contrast, can exist in superpositions of 1 and 0 — that is, they can be both 1 and 0 at the same time. The mathematical result is to vastly increase information capacity and processing power. Consider what a difference this makes: A byte (eight bits) in your computer can store a single number between 0 and 256. A quantum byte, on the other hand, can represent 256 numbers all at the same time. This exponential increase in information capacity represents a significant departure from conventional computing. As with all computing, however, one will still need to run a useful algorithm on this gigantic “information space” and get something useful at the end when measurement destroys the quantum state. Hence there is an emerging field of quantum algorithm development.
The processing speed promised by quantum computers holds out the possibility of solving problems that are exceptionally challenging for even the most powerful supercomputers. For all the wonders of today’s classical computers, there are many things they can’t do, like modelling the chemical structure or reactions of complex molecules. So don’t imagine faster Facebook and Twitter with quantum computers. Instead, imagine new computational tools that solve problems that are practically impossible on conventional hardware.
The Security Implications of Quantum Technology
Quantum technology has some obvious potential applications in the security world. Better atomic clocks, for example, would improve spatial resolution in GPS and allow for more precise targeting and navigation. Quantum communications could allow political and military leaders to exchange messages with enhanced privacy, and to know with high confidence if someone had attempted to seize their information. Quantum computing power may be used to crack encrypted messages, as we describe below.
The security and economic dimensions of just these applications are potentially enormous. Consider espionage and surveillance, for instance. Finding the prime factors of very big numbers — that is, the two numbers divisible only by one and themselves that can be multiplied together to reach a target — is extremely difficult. Make the number big enough and classical computers simply cannot factor them. It would take too long (even in the millions of years) to perform all the calculations necessary to identify its primes. Public key cryptosystems — which is to say, most encryption — rely on the mathematical complexity of factoring primes to keep messages safe from prying computers.
By virtue of their approach to encoding and processing information, however, quantum computers are conjectured to be able to factor primes faster — exponentially faster — than a classical machine. Very simple quantum demonstrations have successfully factored two-digit numbers and research is now focused on how to design and operate a sufficiently large quantum computer to factor long numbers (e.g. 2048 bits). There is a very long way to go in reaching this potential — likely several decades — but a quantum computer that does it would be able to crack even highly resistant encryption. The upshot would be to render vulnerable the entire public-key encryption system, which is today used effectively not only to pass messages but to secure transactions.
Other applications in materials science and chemistry could prove equally impactful, and on much shorter timescales. For instance, it is very difficult to build a computer model that represents all of the possible electron interactions in a molecule, as governed by the rules of quantum physics. As a result, it is challenging for today’s computers to calculate reaction rates, combustion, and other effects. Even using the best-known approximations, modelling relatively simple molecules on the world’s fastest computer could take longer than the age of the universe.
Creating nitrogen-based fertilizer, for instance, consumes nearly 6 percent of the world’s natural gas production, in part because no efficient catalyst has been found for synthesizing it. Yet biological systems perform similar tasks routinely. Today’s computers aren’t up to the task of deciphering how they do it, given the difficulty in modelling the interaction of electrons in chemical reactions. A quantum computer, however, may well be able to do so, and in the process lead to new methods of synthesizing fertilizer. The result would be a freeing up of critical energy resources and better food security.
Quantum computing could also help develop revolutionary artificial intelligence systems. Recent efforts have demonstrated a strong and unexpected link between quantum computation and artificial neural networks, potentially portending new approaches to machine learning. Such advances could lead to vastly improved pattern recognition, for example, which in turn would permit far better machine-based target identification. To imagine one example, the hidden submarine in our vast oceans may become less-hidden in a world with AI-empowered quantum computers, particularly if they are combined with vast data sets acquired through powerful quantum-enabled sensors.
Even the relatively mundane near-term development of new quantum-enhanced clocks may impact security, and beyond just making GPS devices more accurate. Quantum-enabled clocks are so sensitive that they can discern minor gravitational anomalies from a distance. They thus could be deployed by military personnel to detect underground, hardened structures, submarines, or hidden weapons systems. Given their potential for remote sensing, advanced clocks may become a key embedded technology for tomorrow’s warfighter.
For all these examples, we have seen repeatedly in the history of technology development that the most profound impacts of new technologies are generally those least anticipated. ENIAC, one of the first digital electronic computers, was designed in the 1940s primarily to calculate artillery trajectories. The idea that its technology would eventually lead to the Internet, the iPhone, and the FitBit would have boggled the minds of ENIAC’s creators. Similarly, quantum technology holds the promise to transform the world in ways not possible to imagine today.
The Global Landscape
For many years quantum technology was a field dominated by U.S.-based efforts, but the landscape is changing rapidly. The federal government was one of the field’s first strategic investors in the 1990s, funding major university-based research programs through the National Security Agency, the Department of Defense, and other intelligence community entities. (Indeed, one of us has worked on such U.S. government-funded efforts in the United States and Australia since 2001.) Washington has also built repositories of quantum expertise in the Department of Energy’s laboratories and the National Institute of Standards and Technology, and it has supported work with non-traditional international technology partners like Austria and Australia.
Recently, governments in Europe, the United Kingdom, and Canada have launched new initiatives aimed at establishing domestic research workforces and a new quantum technology industry. These efforts build on longstanding strengths in fundamental physics disciplines such as quantum optics, atomic physics, and precision metrology. The scope and scale of the challenge in realizing useful quantum technologies means that these investments from traditional European allies are good for the United States. Further, U.S. co-investment in these efforts helps to ensure that domestic agencies remain integrated into top-tier research programs and major technical developments are known well in advance to U.S. agencies.
The work is not taking place only in friendly nations. Chinese research strength in quantum technology has traditionally focused on quantum communications, and China is now a global leader in the field. Following Alibaba’s investments, China has made rapid progress in output related to experimentalquantum computing and recently announced multi-billion-dollar investments in the field. Russia has seen very limited public progress in the field (after having made seminal foundational contributions to quantum physics), but Russian scientists have recently emerged as co-authors on a major new experiment.
One area where the United States holds a distinct advantage is in the role of U.S.-based or -founded technology companies. The research and development community is increasingly moving away from its traditional focus on university labs, as a large and growing commercial ecosystem develops in response to research breakthroughs. IBM, for example, has recently accelerated its decades-long quantum investments and even brought online an early stage quantum computer (consisting of just 16 qubits) for free user access. Google recently invested in a research team at the University of California to seed a growing in-house quantum effort. Microsoft has inked global partnerships to link university academics with its own in-house quantum computer science theory effort. Similarly, Silicon Valley venture capitalists are entering the field, and now support a number of quantum-focused startups. The size and scale of U.S. venture capital, relative to the global supply, continues to make Silicon Valley a preferred destination for new startups — another strategic advantage for the United States.
Leaping Ahead
The United States holds major strategic advantages in the quantum race. It’s not just the supply of American venture capital, the location of Silicon Valley, or our collection of collaborative allies. The United States also has a highly competent, cleared contractor base, trusted foundries, national laboratories, and federally funded research and development centers. American investment has, however, tended to be ad hoc and disparate, and expertise has traditionally been based in highly independent academic laboratories.
Over the years there have been a variety of efforts to survey the landscape and identify opportunities in quantum technology. The Trump administration should move past paper studies and act, articulating a clear vision for quantum technology —and quantum computing in particular — and a path by which the country can realistically attain it. Recently the U.S. House of Representatives began holding hearings on U.S. leadership on quantum technology, a welcome sign of action.
Fundamental challenges remain in moving from the promise of quantum technologies to a world in which they augment national security, enhance national prosperity, and improve everyday lives. Overcoming these hurdles will require not just the right levels of funding and attracting a world-class talent base, but also working with partners abroad to leverage common efforts. Collaboration with strategic allies — especially the Five Eyes — has been essential to American leadership up to now, and it will be critical to U.S. technical superiority in the field in the future.
In light of rapidly progressing technological advances, national security experts will need to become more familiar with the basic concepts of quantum technology, and sensitive to its potential and limitations. Many professionals can describe the basic ways in which Iran has enriched uranium, talk about the various kinds of cyberattacks, or wax eloquent about the possibilities of big data-enabled AI. It’s time to add quantum technology to the intellectual toolkit of today’s national security policymakers and analysts.
We hope that this primer takes a modest step in that direction. America’s national security edge will turn in part on maintaining the gap between our own advanced technologies and those of our adversaries and competitors. In this race, quantum technology will have an uncertain but potentially transformative role to play. Now is the time to start harnessing the country’s unique advantages and working with partners to multiply them.
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