By Eric Vandenbroeck and co-workers
The Race to Lead the Quantum Future
Over the last several
years, as rapid advances in artificial intelligence have gained enormous public
attention and critical scrutiny, another crucial technology has been evolving
largely out of public view. Once confined to the province of abstract theory,
quantum computing seeks to use operations based on quantum mechanics to crack
computational problems that were previously considered unsolvable. Although the
technology is still in its infancy, it is already clear that quantum computing
could have profound implications for national security and the global economy
in the decades to come.
Since the late 2010s,
the United States and many other advanced countries have become
increasingly involved in the race for leadership in quantum information science
and technology, a field that encompasses quantum computing, quantum communications,
and quantum sensing. Over the last decade, governments in 20 countries have
announced investments in quantum development totaling more than $40 billion
worldwide; China alone has committed to spend $15.3 billion over five years. In
2016, Beijing designated the development of quantum technologies as a national
priority, and it has created advanced hubs for production. For its part, the
United States, in 2018, enacted the National Quantum Initiative, legislation
aimed at maintaining the country’s technological and scientific lead in quantum
information and its applications. The U.S. government has announced $3.7
billion in unclassified funding, plus more funding for defense research and
development. In addition to government-led initiatives, multiple research and
development efforts are underway in the private sector and academia.
Although these
investments are still dwarfed by U.S. and international funding for AI, the
rise of quantum technology has already begun to shape international policy. In
2019, the United States announced a bilateral “statement on quantum
cooperation” with Japan, which the U.S. government strengthened in 2023.
And in 2024, Washington established a multilateral initiative called the
Quantum Development Group to coordinate strategies for advancing and managing
the new technology. The United States has also discussed quantum issues within
various economic and security forums, including AUKUS, the trilateral defense
pact among Australia, the United Kingdom, and the United States; the Quad, or
Quadrilateral Security Dialogue, among Australia, India, Japan, and the United
States; and the U.S.-EU Trade and Technology Council. Underscoring the growing
concerns about the technology in Washington, one analyst for the Center for a
New American Security argued in November, following the U.S. presidential
election, that the incoming administration must “act quickly during the first
100 days to reinvigorate America’s quantum competitiveness.”
Thus far, the advent
of quantum technology has been perceived largely as a national security issue.
Since the 1990s, researchers have recognized that one of the greatest threats
posed by a powerful quantum computer is its potential as a code-breaking tool,
capable of penetrating the encryption used by the most advanced communication
systems and digital networks around the world today. This concern has spurred
the U.S. government to develop and advocate for the adoption of
quantum-resistant cryptography, strengthen export controls on quantum
technology and related products, and build action-oriented partnerships with
industry, academia, and local governments.
However, the focus on
codebreaking has led policymakers to ignore other important applications of
quantum technology. Before quantum machines could crack advanced encryption
systems—a capability that will require enormous computational power even after
the technology is developed—they could have a transformational effect in many
sectors of the economy, including energy and pharmaceuticals. Effectively
harnessed, quantum technologies could spur innovation, scientific discovery,
economic growth, and opportunity. In sheer human impact, some of the
breakthroughs that could be unlocked by quantum machines rival those that are
now projected to come from AI. For this reason, the technology must be
developed in open societies, with clear guardrails in place to ensure that it
is used for benevolent purposes.
Winning the quantum
race will not be easy. China has already taken the lead in some areas
such as quantum communications, and in the coming years, focused American
innovation and leadership will be critical to maintain U.S. competitiveness.
The United States and its international partners will need to commit far more
resources to bring their quantum projects to fruition, and they will have to
develop quantum industries and a strong quantum supply chain to support these
projects. If the United States and its allies fail to make these efforts a
central strategic goal and policymaking priority, they could lose diplomatic
influence, military might, and the ability to provide oversight of a powerful
new technology. They could also miss out on the chance to forge a new path for
economic and societal progress.
Everywhere All at Once
The concept of a
quantum computer was first proposed by the theoretical physicist and Nobel
laureate Richard Feynman in 1981. Feynman came of age during the dawn of
quantum mechanics, when scientists began to recognize that atoms, electrons,
light, and other sub-nanoscale objects—building blocks for everything in the
universe—obey fundamentally different rules than the objects of everyday life.
Unlike, for example, a ball, which follows the straightforward rules of
classical mechanics, electrons behave simultaneously as particles and waves,
and their location cannot be exactly defined.
Feynman’s insight was
that to truly understand the quantum mechanical world—and the general workings
of the universe itself—it would be necessary to build a computer that operates
according to the same laws. “Nature isn’t classical, dammit,” he said, “and if
you want to make a simulation of nature, you’d better make it quantum
mechanical.”
Configuring a dilution refrigerator in Elmsford, New
York, March 2023
Feynman’s insight has
turned out to be prescient. In the more than four decades since, computers
following the “classical” design have utterly transformed the planet:
pocket-sized mobile phones today are a million times as powerful as the hulking
desktop personal computers of the 1980s. Moore’s law—the prediction that the
number of transistors on a computer chip would double every two years—has
continued to broadly hold true in the semiconductor industry, despite multiple
predictions of its demise. And the best supercomputers today can handle a
quintillion—that is, a billion billion—operations per second. Yet as this
revolution continues to mature, it has become increasingly clear that some
computations are and will remain beyond even the best classical computers.
This is because existing
computer technologies are constrained by the basic premise on which they
operate. All forms of classical computing, whether an abacus, a personal
laptop, or a high-performance cluster of machines in a national security
facility, follow what scholars call Boolean logic. In this system, the basic
unit of information is a bit, which is an object that can assume one of two
states, conventionally referred to as 0 or 1. Although this system has proved
highly efficient for many kinds of calculations, it cannot perform those of
exceeding complexity, such as factoring a thousand-digit number, calculating
the reaction dynamics of a molecule with hundreds of atoms, or solving certain
kinds of optimization problems that are common in many fields.
In contrast, by
harnessing quantum mechanics, quantum computing does not have the same
constraints. A lesson of quantum physics—one that is startling and
counterintuitive—is that particles can exist in a simultaneous combination of
multiple states. Accordingly, instead of bits, with their either-or operation,
quantum computing uses a quantum bit, or qubit, which is a system that can be
simultaneously in states 0 and 1. This both-at-once ability, known as
superposition, conveys an enormous computational advantage, one that increases
when more qubits are working together. Whereas a classical computer must
process one state after another sequentially, a quantum computer can explore
many possibilities in parallel. Think of trying to find the correct path through
a maze: a classical computer has to try each path one by one; a quantum
computer can explore multiple paths simultaneously, making it orders of
magnitude faster for certain tasks. It is important to note that contrary to
popular simplification, a quantum computer is not simply an enormous set of
classical computers working in parallel. Although there are exponentially many
possible answers that can be explored through a quantum processor, only one
combination can be measured in the end. Deriving a solution from a quantum
computer thus requires clever programming that amplifies the correct answer.
A major challenge is
figuring out how to build quantum processors that are large and stable enough
to produce consistent results for meaningful problems. Such processors tend to
be extremely sensitive to their environment and can be easily affected by changes
in temperature, vibrations, and other disturbances, which can lead to a variety
of errors in the system. Since computational fidelity relies on qubits
maintaining coherence, researchers are investing heavily in methods to improve
qubit quality, including new designs, chip-fabrication processes, and
techniques to correct qubit errors.
Currently, there is a
wide array of approaches to designing qubits, each with its advantages and
drawbacks. In principle, any quantum mechanical system—atoms, molecules, ions,
photons—could be fashioned into a qubit. In practice, factors such as manufacturability,
controllability, performance, and computational speed dictate the most viable
paths. Today’s leading efforts include superconducting, neutral atom, photonic,
and ion trap qubits. It is unclear at this early stage which, if any, will turn
out to be successful. Beyond building the processor, other challenges include
how to package the qubits, transmit their signals, and run applications.
Researchers must use cryogenic refrigerators, which can cool superconducting
qubits to within thousandths of a degree above absolute zero, to provide an
ultracold, dark, and quiet environment for operation. Expertise across these
highly specialized components comes from disparate sources in many countries.
Today, there are various “full-stack” quantum computing companies, including
Amazon, Google, IBM, and QuEra, that are trying to integrate components into a
final product. In short, quantum computing today faces a multitude of
challenges and unknowns, and continued development will require a host of
engineering innovations. What is clear is that for any of the approaches to
succeed, they must be reliable, scalable, and cost-effective.
The New Answering Machines
The race to arrive at
a full-scale quantum computer is driven by several motives. Most fundamentally,
quantum computing promises to provide answers to problems previously thought
unsolvable—puzzles that would take eons for the world’s best classical computers
to crack. The most well-known problem of this kind is integer factorization, or
breaking down a number as a product of several smaller numbers: even the
fastest supercomputers are unable to factor very large numbers. This has meant
that the most advanced forms of cryptography—which are based on
factorization—cannot now be broken. But quantum computers may change that.
In 1994, the computer
scientist Peter Shor proved that a quantum computer would be able to factor
very large numbers. At the time, such a computer remained firmly in the realm
of theory, but as the technology has begun to develop, Shor’s insight has led to
concerns that quantum processors may one day be capable of breaking even the
most advanced encryption. Today, national security experts assume that hostile
state and private actors are already collecting encrypted information in
anticipation of the new technology, an approach known as a “store now, decrypt
later” attack.
But decryption is
only one possible application for quantum computers, and it is likely more than
a decade away. As Feynman intuited, more obvious uses for quantum-based
computing relate to quantum simulation—the ability to make exact calculations
of quantum systems such as electrons, molecules, and materials—and these
applications could begin to come into use sooner. Quantum processors are
already contributing to discoveries in a number of highly specialized areas in
physics—including quasiparticle engineering, many-body dynamics, spin
transport, metallic transport, time crystals, wormhole dynamics, and
magnetization. With a full-scale, full-capability quantum computer, the
possibilities are astounding. Consider agricultural fertilizers. At present,
nitrogen fixation—the chemical process required to produce ammonia from
nitrogen gas—is hugely energy intensive, accounting for as much as two percent
of the world’s annual energy budget. This is because the industrial catalysts
used in this reaction are highly inefficient. In fact, the naturally occurring FeMoco molecule, a catalyst for biological nitrogen
fixation, is far more efficient, but it cannot yet be chemically synthesized or
isolated in industrial-scale quantities, and its mechanism of action has proven
too challenging for existing computing technology to elucidate. With quantum
computers, however, researchers may be able to perform the difficult
calculations necessary to learn FeMoco’s reaction
mechanism, allowing the design of FeMoco-inspired
catalysts that could save vast amounts of energy.
Google’s “Willow” chip
To assess the current
state of the quantum race, the research arm of the U.S. Department of Defense,
the Defense Advanced Research Projects Agency, or DARPA, recently announced a
Quantum Benchmarking Initiative to determine whether any quantum computing approach
can achieve utility-scale operation by 2033. Although it is impossible to
predict the exact pace of future innovation, some researchers have estimated
that prototypes of full-scale quantum computers, consisting of perhaps ten
logical qubits, may be developed by the end of this decade. Such a feat,
together with improved error-correction methods and more efficient algorithms,
would bring the world tantalizingly close to quantum simulation.
By current estimates,
researchers are unlikely to achieve the first true quantum code-breaking
machine—a quantum computer with millions of qubits and adequate error
correction—until the late 2030s. Even then, such a computer would take hours to
factor a single large number. Still, it is crucial for the United States and
its international partners to prepare for this technology now. Networks have
been notoriously slow to implement new security standards, despite their long
availability. It will take years to develop, test, and refine a set of
quantum-secure standards. The U.S. National Institute of Standards and
Technology has been leading an effort since 2016 to develop cryptography
standards for a post-quantum world. In August 2024, NIST announced a first set
of three classical encryption algorithms as standards ready for immediate use,
with instructions for integration into encryption systems and other products.
Although this set of algorithms is impervious to all published decryption
methods today, it is possible that one or more of them could be vulnerable in
the future. Such concerns have taken on added urgency in the wake of new
research suggesting that public encryption may never be fully secure against
quantum attacks.
Like other new and
powerful technologies, quantum computing holds enormous promise, and it also
introduces significant new risks. In addition to large-scale data theft,
economic disruption, and intelligence breaches, quantum computers could be used
for malicious purposes such as simulating and synthesizing chemical weapons or
optimizing the flight trajectories of a swarm of drones. As with AI, the possibility of misuse or abuse raises critical
questions about who should control the technology and how to mitigate the worst
threats. Policymakers will need to determine how to maximize economic and
societal gains while minimizing the dangers. Finding the best ways to achieve
this balance will require a rigorous debate within civil society and an
understanding by the public of the technology’s potential gains and harms.
There are multiple futures for a world with quantum computers. The best one would
see liberal democracies leading both the technology’s development and its
collective management. A worse one would have the United States and its
international partners, through inaction or insufficient actions, cede
dominance of the new technology to China and other autocratic countries.
Quantum Leap
Perfecting the
quantum computer is a bold, ambitious, and multifaceted project and not one
that any company or country can accomplish on its own. Today’s early systems
already require thousands of specialty parts, tools, and instruments;
sophisticated fabrication and cryogenic facilities; and world-class mastery in
dozens of technical areas, all supported by billions of dollars of investment
in research and development. Tomorrow’s systems will be appreciably more
complex. If the United States is to lead this race and, together with its
international allies, build the most advanced quantum computing systems, it
must allow quantum workers to collaborate across sectors and borders. Effective
collaboration can give liberal democracies a significant advantage over more
closed, authoritarian countries.
For many companies working
on quantum systems today, quantum processors are the crown jewel of their
intellectual property and are fabricated in their home country: Google makes
quantum chips in the United States, Oxford Quantum Circuits produces quantum
chips in the United Kingdom, and Alice & Bob does so in France. In
each case, these chips are for in-house research and development; in some
instances, third parties are allowed to access early prototypes. As the
semiconductor sector has demonstrated, there are geopolitical advantages for
any country to maintain the domestic capacity to build a strategic component.
But in order to
fabricate processors and integrate full computer systems locally, the necessary
talent must also be available. This requires collaboration among government
entities, industries, and research and educational institutions. Quantum
computing companies can support this process by sharing their anticipated
workforce needs and providing on-the-job training opportunities. Because the
skill sets required for quantum computing are highly specialized, it will not
be possible for every country—and may not even be possible for any one
country—to develop all the talent needed. Our own work in quantum computing
involves collaborations with over 100 academic institutions and industry
partners across the United States, Europe, and the Asia-Pacific. The United
States and its allies would be wise to implement visa, immigration, and export
control policies that allow companies in this critical sector to recruit the
most talented scientists, engineers, and technicians. In September, the U.S.
Department of Commerce took an important step in this direction by announcing
new rules that include a deemed export exemption to facilitate the employment
of highly skilled international workers in the United States.
Washington and its
international partners will also need to establish strong supply chains for all
the subsystems and components that go into quantum computing. Many of the
necessary components are and will continue to be produced in disparate
locations around the world. Building superconducting qubits, for example,
requires many of the same tools that are used in advanced
semiconductor-fabrication facilities owned by companies such as Intel and TSMC;
these tools are manufactured in France, Germany, the Netherlands, and the
United States, among other countries. Cryogenic refrigerators require expertise
that is possessed by only a handful of companies, most based in the United
Kingdom and the EU. Still other components, such as control electronics and
wiring, are designed by specialized companies in Israel, Japan, and Taiwan, as
well as in the United States and the EU. Individual countries may attain
mastery of different pieces, but like-minded states will need to work together
to assemble the full puzzle and keep it out of the reach of authoritarian
states.
For quantum computing
to achieve its full potential, creative minds from many different disciplines
will be needed to develop uses for the technology. There are several early
efforts to foster a developer ecosystem, including DARPA’s Quantum Benchmarking
program, which measures progress toward potential application areas, and XPRIZE
Quantum Applications, a three-year, $5 million international competition to
generate new quantum computing algorithms for real-world challenges. Gains will
come from software developers creating easy interfaces for access, academics
and business leaders using these interfaces for the problems most important to
them, and consumers and civil society providing input on what they find most
valuable.
Like the race to land
humans on the moon or to sequence all the genes in the human genome, the
successful and safe development of quantum computing cannot be achieved by
scientists alone. It will require generational public and private commitments
of resources and talent and farsighted international diplomacy. Quantum
computers will create extraordinary opportunities for the United States and
many other countries around the world. They will also pose new risks, including
the potential for abuse or misuse, and possible shocks to the world order. If
these dangers can be managed, the potential of quantum computing to accelerate
human progress and build a better future could be incredible.
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