Congress passed and the President signed into law the National Quantum Initiative Act (NQI Act; P.L. 115-368; codified at 15 U.S.C. §§8801 et seq.) in December 2018 to accelerate quantum research and development (R&D) for the economic and national security of the United States and ensure the continued U.S. leadership in quantum information science and its technology applications. Since the enactment of the NQI Act, researchers have made progress in quantum R&D, while the authorization of funding for several federal R&D activities under the NQI Act is set to expire at the end of FY2023. As Congress contemplates whether to reauthorize the NQI Act and continue appropriations, there are a number of questions it may consider: What is the current state of quantum technologies? How far are current R&D activities from delivering useful quantum systems and applications? What resources are needed to accelerate R&D in the field and how should those resources be prioritized? How can federal agencies further coordinate and facilitate authorized R&D efforts in collaboration with industry, academia, and global partners?

This report uses one particular quantum information technology—quantum computing—to explain concepts such as quantum superposition, entanglement, and qubit, and the current state of the field, including recent technical milestones. The report also provides an overview of relevant federal laws—the NQI Act as well as quantum provisions in annual National Defense Authorization Acts (NDAAs) and the CHIPS and Science Act. Finally, the report discusses current policy issues that Congress may opt to consider: (1) reauthorizing federal R&D activities under the NQI Act; (2) ensuring continued U.S. leadership in quantum computing through accelerating near-term applications, developing a robust supply chain, and facilitating workforce development; and (3) assessing and protecting national security interests with advances in quantum computing.

Concepts of Quantum Computing

Congress has defined some key terms related to quantum computing in federal law. In the NQI Act, the term quantum information science means "the use of the laws of quantum physics for the storage, transmission, manipulation, computing, or measurement of information."¹ In the Quantum Computing Cybersecurity Preparedness Act (P.L. 117-260), the term quantum computer means a computer that "uses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations."² In addition to these statutory definitions, reports issued under the National Quantum Initiative Program established in the NQI Act use the term quantum information science and technology (QIST) to refer to the understanding and applications of quantum information science to design new types of computers, networks, and sensors that "enable new speed, precision, or functionality."³

Specifically, quantum computing—part of the umbrella concept of QIST—is an emerging computing paradigm that harnesses the principles of quantum mechanics to represent, store, process, and transmit data.⁴ In quantum computing the basic data unit is a quantum bit, or qubit, the equivalent of a bit in conventional, non-quantum computers (also called classical computers).⁵ A quantum computer's data processing power is largely contingent upon the effective and efficient generation and manipulation of qubits.⁶ Scientists have physically created and controlled qubits using superconducting materials and devices,⁷ or tiny objects such as atoms, electrons, trapped ions, or photons.⁸

Unlike a classical bit that can represent only one piece of information, either 0 or 1, a qubit can represent more mathematically-rich information by being in a superposition, which can be expressed as a combination of a certain probability of being in 0 and a certain probability of being in 1.⁹ Qubits can be entangled with one another, so that a quantum computer can manipulate a group of qubits in a single operation, unlike in classical computing where the same operation needs to be performed on each bit individually.¹⁰ Computer algorithms specially designed to take advantage of these unique qubit properties of superposition and entanglement will allow quantum computers to perform multiple tasks simultaneously and certain calculations significantly faster than classical computers, leading to new ways to solve some complex problems that are intractable for classical computers at any scale (even high-performance supercomputers).¹¹

In short, as the number of qubits increases linearly, the information that the qubits are capable of carrying grows exponentially. In classical computing, doubling the number of bits only doubles its computational power to handle data. See Appendix A for the explanation for the terms of quantum, quantum mechanics, quantum superposition, and quantum entanglement.

Resolving computationally complex problems typically requires dealing with a large number of variables that interact in complicated ways, with multiple possible and uncertain outcomes.¹² Solving these problems requires a vast amount of computing resources and is time-consuming. Examples include modeling the behavior of individual atoms in a molecule; simulating all possible interactions when two objects collide with each other; optimizing a set of routes for a fleet of vehicles to deliver packages to customers in different locations; factoring a large composite integer into a product of prime numbers in cryptographic algorithms; and identifying fraud patterns in financial transactions. Researchers have demonstrated the potential for quantum computing to solve complex problems in areas such as cryptography, machine learning, and scientific and engineering research, particularly using modeling, optimization, and simulation (e.g., for the study of quantum physics, chemistry, and material science, and for new drug development).¹³ However, there are practical implementation challenges such as maintaining a qubit's superposition and correcting calculation errors (discussed in the following sub-section, "Increasing Quantum Computing Reliability"), leading to uncertainty about whether and when quantum computing could be broadly deployed and applied.

The Current State of Quantum Computing

Since the enactment of the NQI Act in 2018, researchers have made notable advances in quantum computing in three specific areas.

Demonstrating Quantum Advantage

In October 2019, a research team led by scientists from Google's quantum group reported that a quantum processor with 54 qubits took about 200 seconds to complete a specially designed computation; an equivalent computation would take a state-of-the-art classical supercomputer approximately 10,000 years. The researchers claimed that their experiment demonstrated a milestone for quantum computing—the first computational task executed much faster on a quantum processor than on a classical processor. This achievement also demonstrated so-called "quantum advantage" or "quantum speedup" over classical computing.

In April 2023, another research team led by the same Google group reported that a second generation of its quantum processor, with 70 qubits, performed a more complex task than the one reported in 2019. According to the researchers' estimate, the same task would take about 47 years for the Frontier supercomputer at Oak Ridge National Laboratory—the fastest classical computing system in the world at the time.¹⁴ The researchers claimed that such a computational task was beyond the capabilities of many existing classical supercomputers.¹⁵

Despite these successes, some experts argue that researchers have thus far only demonstrated quantum advantage over classical computers in solving mathematical proofs and that quantum advantage may not have practical value beyond academic research.¹⁶

Increasing Quantum Computing Reliability

To make quantum computing broadly applicable in solving practical problems, researchers have recognized the need for technical advances to increase the reliability of quantum computers.¹⁷ Many researchers agree that a major outstanding challenge to quantum computing is "noise," which can affect the accuracy of calculations made by a quantum computer.¹⁸ Noise refers to any disturbance to a qubit's environment, such as heat, light, thermal vibrations, electromagnetic radiation, Earth's magnetic field, cosmic rays, or neighboring qubits, among others.¹⁹ Qubits are highly susceptible to noise, which can cause the loss of information it holds.²⁰ Error rates are generally higher in quantum computers than in classical computers.²¹

Noise introduces errors in quantum calculations that are difficult to correct²² and limits the number of qubits a quantum computer can have.²³ Solutions to this challenge include developing fault-tolerant quantum processors or running fully error-corrected quantum algorithms. Both approaches require at least tens of thousands of qubits,²⁴ well beyond the capacity of current quantum processors.²⁵

Some promising recent research results point to the possible development of techniques that may help reduce error and increase reliability. In June 2023, a team led by IBM quantum researchers presented the results of an experiment to "controllably manipulate" quantum noise, demonstrating success in an experimental setting.²⁶ Google's quantum research group reported in February 2023 that its researchers were able to demonstrate that increasing the number of qubits can lower the error rate of calculations in a quantum computer.²⁷ The researchers admitted that the improvement on the error rate in their experiment was still small, and error rates needs to drop much more to realize the potential of solving problems beyond the reach of classical computers.²⁸ Some experts argue that progress so far has mitigated, but not fully corrected, calculation errors, and only full quantum error correction can truly enable reliable quantum computing.²⁹

Achieving Quantum Advantage for Practical Problems

Some experts have suggested focusing on the development of quantum computers that provide practical quantum advantage, beyond simulating and testing quantum hardware.³⁰ Practical quantum advantage means using quantum computers to reliably tackle useful, real-world problems that leading classical supercomputers cannot address. It will require a large-scale quantum computer with thousands, hundreds of thousands, or even millions of qubits, depending on factors such as the type of problem, the algorithm, and the architecture of the quantum hardware.³¹ Quantum processors at this scale do not yet exist.

To achieve practical quantum advantage, leading industry players have set their R&D roadmaps to scale up quantum processors with qubits. In November 2022, IBM announced a 433-qubit processor based on superconducting technology.³² The company claimed that it was on track to deliver a 1,000-qubit processor by the end of 2023.³³ In May 2023, IBM launched a $100 million partnership with the University of Tokyo and the University of Chicago, aiming to develop a quantum supercomputer by 2033 powered by 100,000 qubits,³⁴ which it predicts will allow the supercomputer to perform some useful tasks with practical quantum advantage.³⁵

Researchers at Google believe that scaling up qubits also helps to improve quantum error correction—the required feature of general-purpose quantum computers.³⁶ Google is reportedly working toward a 1,000-qubit processor and expects to achieve this milestone as early as 2025.³⁷ It hopes to demonstrate a useful, error-corrected quantum computer with one million qubits within a decade.³⁸

Federal Law Concerning Quantum Computing

Since the NQI Act was enacted in December 2018,³⁹ it has been amended by the National Defense Authorization Act (NDAA) for FY2022 (P.L. 117-81) and the CHIPS and Science Act (Division B of P.L. 117-167).⁴⁰ In addition to these amendments, the CHIPS and Science Act, the American COMPETES Act (Title XV of P.L. 116-260), and the NDAAs for FY2019 (P.L. 115-232), FY2020 (P.L. 116-92), FY2021 (P.L. 116-283), FY2022 (P.L. 117-81), and FY2023 (P.L. 117-263) contain other provisions pertinent to R&D activities in quantum computing. This section summarizes highlights of those provisions.

Federal R&D Investments in Quantum Information Science and Technology

Actual budget expenditures for federal QIST R&D activities at federal agencies totaled nearly $2 billion between FY2019-FY2021, or an average of $667 million per fiscal year.⁶⁴ These expenditures supported R&D activities conducted by NIST, NSF, DOE, DOD, the Department of Homeland Security (DHS), and the National Aeronautics and Space Administration (NASA).⁶⁵ These agencies reported an enacted budget authority of $918 million for FY2022 for QIST R&D activities, and a requested budget authority of $844 million for FY2023.⁶⁶ A large portion of the budget expenditures and budget authorities are for activities authorized in the NQI Act, as shown in Table 1.

Policy Considerations for Congress

Congress may be interested in considering policy issues surrounding the reauthorization of funding for several R&D activities under the NQI Act, which is set to expire at the end of FY2023. The funded programs and activities include NSF's five university-based Quantum Leap Challenge Institutes, DOE's five national lab-led research centers, and NIST's R&D activities such as the industry-led Quantum Economic Development Consortium (QED-C) (see Table 1, Table B-1, and Table B-2).

Many experts contend that sustained federal investment in QIST R&D generally is necessary to accelerate progress toward practical quantum computing and to maintain a leading role of U.S. researchers in quantum computing R&D globally.⁶⁷ There is less consensus, however, on the specific role the federal government should play, if any, in QIST R&D and how resources and support should be specifically targeted and prioritized to accelerate R&D in the field. Areas for possible congressional action include the following:

Reauthorizing Federal R&D Activities Under the NQI Act

When contemplating reauthorization, Congress may wish to consider the following options:

• 1. Whether to reauthorize and continue funding the existing NSF and DOE research and education centers and NIST activities, perhaps for a duration aligned with the sunset date of December 21, 2029, when the authority to carry out the National Quantum Initiative in the NQI Act expires.⁶⁸
• 2. Whether to increase the number of centers that NSF and DOE are authorized to support. The current maximum number is five for each agency.⁶⁹
• 3. Whether the current model of supporting national-level, large-scale centers is sustainable and effective to deliver practical quantum computers; whether to broaden federal support to include other research and education institutions, startups, small and medium-sized R&D enterprises, and individual principal investigators; and whether to widen the focus of support from basic to applied science and engineering research focused on making and testing scalable quantum systems and developing quantum software.⁷⁰
• 4. Whether to expand the NQI Act-authorized activities conducted by NIST, NSF, and DOE to include other agencies, such as NASA, DHS, the National Institutes of Health (NIH), and the National Telecommunications and Information Administration (NTIA).
• 5. Whether to prioritize particular aspects of quantum computing, networking, sensing, and their applications. While quantum computing is the most anticipated and most challenging quantum technology, quantum networking—which may be implementable for some near-term applications—has important implications for the development of advanced information infrastructure, where the United States faces substantial competition from other countries such as China.⁷¹
• 6. Whether to encourage and provide oversight of quantum R&D collaboration and coordination among federal agencies, national laboratories, academia, industry, and entities in allied countries. For example, a bipartisan bill introduced in the 118^th Congress, S. 2450, would amend the NQI Act to "ensure the coordination, and avoid unnecessary duplication," of DOE and NSF activities authorized under the NQI Act. It would also direct QED-C to conduct a study of the impediments to collaboration between NSF research and education centers, DOE research centers, industry, and academia.⁷²
• 7. Whether to direct any agency that conducts authorized and funded R&D activities to report its progress to Congress at some regular interval.⁷³ Among the current authorized activities established in the NQI Act, there is one statutory reporting requirement: NIST shall submit a report to congressional oversight committees summarizing QED-C findings.⁷⁴

Ensuring Continued U.S. Leadership in Quantum Computing

As discussed in the section "The Current State of Quantum Computing," researchers in the United States, many supported by federal programs, have made substantial progress in quantum computing R&D since the enactment of the NQI Act. This has helped establish U.S. leadership in this still nascent but promising field. To ensure and strengthen U.S. leadership, Congress may wish to consider three policy priorities when addressing quantum computing.

Accelerating the Development of Practical Quantum Computers with Near-Term Applications

The current global competition in quantum computing is essentially a race to achieve practical quantum advantage and solve practical problems. This requires breakthroughs in quantum error correction and scaled-up quantum processors with a larger number of qubits.

A bipartisan bill in the 118^th Congress, the Quantum Sandbox for Near-Term Applications Act of 2023 (S. 1439/H.R. 2739), would amend the NQI Act by directing the Department of Commerce (DOC), in coordination with NIST, to establish a public-private partnership "focused on quantum computing application development acceleration for quantum, quantum communication, quantum sensing, and quantum-hybrid computing near-term use cases."⁷⁵ To carry out this mandate, the bill says DOC should, acting through NIST, engage with QED-C, national laboratories, federally funded R&D centers, and other members of the U.S. quantum computing ecosystem.⁷⁶

Another bill, the Leveraging Quantum Computing Act (H.R. 3987), would engage federal agencies "to identify potential use cases with respect to which quantum computing could advance the missions of such agencies, including through on-premises, cloud-based, hybrid, or networked approaches."⁷⁷

Additionally, Congress may wish to consider targeting federal support toward specific priorities. To accelerate near-term applications of quantum computing, an option could be to direct federal agencies to support the development and testing of quantum algorithms and fault-tolerant quantum processors, and the development of computer networks to allow researchers and developers to access quantum computing resources through cloud computing services.

Supporting the Development of a Quantum Supply Chain

To build quantum computers at scale, industry has identified the strategic priority of developing an accessible, sustainable, and secure supply chain and independent manufacturing capabilities that can foster a healthy and stable quantum computing ecosystem. According to an industry survey commissioned by QED-C in June 2022, "key raw materials" and "key manufacturing/assembly equipment" were thought to be the top two "most likely causes of a [quantum computing] supply chain interruption in the next three years."⁷⁸

Quantum computing technologies are not mature enough to provide certain and sufficient market demand to have an established and extant supply chain.⁷⁹ Different approaches to the physical implementation of quantum computing may lead to a variety of, as yet unknown, mineral, material, and equipment requirements,⁸⁰ some of which may be under the control of non-allied countries.⁸¹

To address these issues, S. 2450 would direct DOC, through NIST and in consultation with DOE, to (1) determine the manufacturing capabilities to produce reliable quantum components and systems at scale and the gaps in access to such capabilities; and (2) establish a Manufacturing USA institute that provides an end-to-end manufacturing ecosystem addressing quantum computing, sensing, and networking and supports the development of a resilient quantum supply chain.⁸²

Other options for Congress could include the following:

• Directing a federal agency or body, such as the National Quantum Coordination Office, to study and report on the global quantum computing supply chain and identify risks and security concerns.
• Establishing proactive policies to avoid similar supply chain and manufacturing issues faced by the classical computer chip industry. These may include directing and funding federal agencies to support material science and computer engineering research dedicated to developing additional domestic quantum computing capacity, and to programs that support the establishment and maintenance of domestic quantum manufacturing capabilities.
• Imposing export controls for critical quantum computing materials and components.

Facilitating Workforce Development for Quantum Computing

Many experts maintain that training, recruiting, and retaining talent are important for sustaining U.S. leadership in quantum computing hardware and software R&D.⁸³ The National Science and Technology Council Subcommittee on Quantum Information Science has recommended four strategic actions: (1) understanding the workforce needs in the QIST ecosystem; (2) introducing broader audiences to QIST through public outreach; (3) enhancing QIST-specific education and training opportunities; and (4) making careers in QIST and related fields more accessible and equitable.⁸⁴ In the abovementioned QED-C industry survey, respondents identified a potential skilled workforce shortage in the United States in optical, mechanical, and electronics engineers, and software developers.⁸⁵

In the CHIPS and Science Act, Congress has authorized $8 million per year for FY2023-FY2026 for NSF to carry out QIST workforce development activities, including (1) commissioning the National Academies of Sciences, Engineering, and Medicine to conduct a study to evaluate and make recommendations for the workforce; and (2) making awards to carry out the Next Generation Quantum Leaders Pilot Program to educate and train K-12 students and teachers in the fundamental principles of quantum mechanics.⁸⁶

Congress may wish to consider policies to encourage domestic high school and college students to participate in related STEM (science, technology, engineering, and mathematics) education courses and programs that are foundational to QIST.⁸⁷ Quantum computing relies upon knowledge and research in a number of disciplines (e.g., quantum physics, mathematics, chemistry, electrical engineering, software engineering, bioengineering, computer science and engineering, and information science, among others). Courses and curricula in relevant fields may help develop a quantum-literate workforce in general and prepare students with necessary knowledge and skillsets to work in quantum computing in private and public sectors.

Protecting National Security Interests in Quantum Computing

Some quantum computing technologies may pose risks to national security if they were to be obtained by adversaries of the United States and other malign actors.⁸⁸ For example, using quantum algorithms,⁸⁹ a practical quantum computer could potentially compromise the cryptography currently used to protect sensitive data communications among government agencies, financial institutions, health service providers, and others.⁹⁰ In general terms, modern cryptography is based on the idea that the intractability of certain mathematical problems provides a reliable approach to enforcing policies for accessing digital data—only someone who holds the authenticated "key" can immediately access the encrypted data; anyone else must first solve a problem, such as factoring the products of large prime numbers.⁹¹ This problem is designed to be impossible to complete within a reasonable time even using (existing, classical) supercomputers, and the difficulty of the problem guarantees the security for a cryptosystem. Some experts claim that a future fault-tolerant quantum computer with millions of qubits could solve such a problem in hours.⁹²

Experts on the National Quantum Initiative Advisory Committee have urged the federal government and industry to work together to simultaneously accelerate progress in QIST, and develop and deploy new encryption algorithms and standards resistant to quantum attacks (also known as "post-quantum cryptography," or PQC).⁹³ Some industry leaders have committed to keeping the government and public informed of their R&D progress toward a practical quantum computer capable of undermining existing encryption.⁹⁴

Since 2016, NIST has worked on its PQC standardization process, which selects cryptographic algorithms that can be implemented on classical computers to protect information that may become vulnerable with the advent of quantum computers.⁹⁵ NIST expects that these algorithms could replace current cryptosystems "to prepare for the eventuality that large-scale quantum computers become a reality."⁹⁶ The agency anticipates finalizing the standard by 2024.⁹⁷ In May 2022, the Biden Administration issued the National Security Memorandum (NSM) on Promoting United States Leadership in Quantum Computing While Mitigating Risks to Vulnerable Cryptographic Systems (NSM-10), which stated that "the United States must prioritize the timely and equitable transition of cryptographic systems to quantum-resistant cryptography, with the goal of mitigating as much of the quantum risk as is feasible by 2035."⁹⁸

In December 2022, Congress passed and the President signed into law the Quantum Computing Cybersecurity Preparedness Act (P.L. 117-260). Congress found a potential for adversaries of the United States "to steal sensitive encrypted data today using classical computers, and wait until sufficiently powerful quantum systems are available to decrypt it."⁹⁹ It directed the Office of Management and Budget to issue guidance on the migration of federal information technology systems to PQC and submit to Congress a report on PQC and a report on the progress of agencies in adopting PQC standards.¹⁰⁰ The law codifies NIST's ongoing work on PQC standards, but does not apply to any national security systems.¹⁰¹

Breaking classical cryptography systems is one highly anticipated use of quantum computing. Congress may wish to consider options to safeguard national security interests, in addition to the abovementioned initiatives and legislative efforts regarding PQC. These options may include whether to

• prioritize federal support for the development of large-scale, practical quantum computers that are capable of implementing quantum algorithms to break existing encryption;
• further support R&D in quantum cryptographic algorithms and standards that can be implemented on quantum computers and to establish new, secure quantum data communications;
• require the disclosure by quantum computer developers when they make substantial progress in breaking existing cryptography systems;
• direct resources to develop a quantum-ready national security workforce;
• strengthen export controls for quantum computing hardware, software, and network equipment, and intellectual property protections for relevant technologies and processes;
• oversee technology transfers and commercialization involving dual-use quantum applications, including cryptography, drug discovery, virus study, and new material development; and
• enforce the review of foreign investments in U.S. entities and U.S. investments in non-partner countries in security-related quantum computing technologies and products.

Appendix A. Key Terms of Quantum Computing Explained

Quantum Networking

Quantum computing, quantum networking, and quantum sensing are closely related to one another. Quantum computing is discussed in the main text of this report. Quantum networking (also called quantum communications) refers to building fast and secure data communication networks that use quantum phenomena such as superposition and entanglement (discussed below) to encode, send, receive, and store information among interconnected quantum devices.¹⁰² Some experts assert that the ultimate goal of quantum networking is building and scaling a quantum-enhanced and protected, full-scale global internet, or quantum internet, not replacing but complementing the existing internet (i.e., a network of networks of classical computing devices).¹⁰³ A quantum internet could be used to connect quantum computers to enable distributed computing services, similar to the ideas of cloud computing and parallel computing for classical computers.¹⁰⁴ Network-enabled quantum computing could unleash even more computing power than individual quantum computers.¹⁰⁵

Quantum Sensing

Quantum sensing refers to the development of quantum-based instruments capable of measuring physical quantities, such as time, temperature, distance, gravity, and electric and magnetic fields, with more sensitivity and precision than conventional sensors such as seismometers, microscopes, or magnetic resonance imaging (MRI) devices.¹⁰⁶ Quantum sensing may have a variety of potential applications, including medical imaging; imaging of molecular structures such as proteins; radio signal receiving and amplification in wireless communications; navigation; environmental monitoring; physical infrastructure monitoring; energy consumption monitoring; geographical surveying; and fundamental research.¹⁰⁷

Quantum computing, networking, and sensing technologies can exist independently, but synergies may arise as these technologies mature.¹⁰⁸ For example, quantum networking may enhance quantum computing and facilitate quantum sensing, and quantum sensing may enable new quantum computing applications, particularly in artificial intelligence.

Quantum

The term refers to either the smallest possible discrete unit of energy that can occur in nature, or a tiny object (e.g., an electron, proton, or neutron in an atom, or a photon of light) that carries such a single unit of energy. At the atomic and subatomic scale, physical properties such as energy are not continuous but rather exist in specific discrete amounts. These properties are called "quantized."¹⁰⁹

Quantum Mechanics

The term refers to the mathematical laws and principles of quantum physics, which describes the behavior, properties, and interactions of quantum. These quantum objects behave often in ways that are unfamiliar and may be counterintuitive and surprising. Many phenomena occurring at the quantum scale cannot be explained by classical physics, which describes nature's behavior at much larger scales that people experience in everyday life.¹¹⁰ Yet those quantum phenomena are essential for QIST.

Quantum Superposition

In quantum mechanics, superposition refers to the fact that an object at the quantum scale (e.g., an electron) can exist in an undetermined state.¹¹¹ This state can be expressed by a combination of possibilities of multiple definite states in which the object may exist.¹¹² For example, an electron could be in a superposition state with probabilities of two spinning directions—40% of the chance it is spinning downward and 60% of the chance it is spinning upward. It does not mean that the electron is in both directions simultaneously; rather, it is in a quantum state that can be only expressed mathematically.

Once a quantum object is measured and interacts with its environment (e.g., other objects, light, vibration, or heat), the superposition state will "collapse" into a particular state.¹¹³ This collapse is called quantum decoherence. Preventing decoherence, so that quantum computers can continue to employ superposition to make reliable calculations, is a major challenge in realizing quantum computing.¹¹⁴

Superposition is one of the fundamental attributes of quantum computers that differentiate them from classical computers. It is an inherently quantum property, not included in classical physics, because classical objects are large enough that they always exist in a single definite state. Quantum computing harnesses this unique property to enable an object at the quantum level to carry more information than a single given state can represent. For example, while two classical bits can represent only a pair of data at a time from the four possible combinations of 0|0, 0|1, 1|0, and 1|1, two qubits can represent possibilities of these four combinations at the same time.¹¹⁵ Following this trajectory, as the number of qubits increases linearly, the information that the qubits are capable of carrying grows exponentially. In classical computing, however, doubling the number of bits only doubles its computational power to handle data.¹¹⁶

Quantum Entanglement

In quantum mechanics, entanglement describes a phenomenon in which two or more quantum objects, when entangled, behave in a correlated way and remain so even if they are physically separated by a large distance.¹¹⁷ Because of this correlation, measuring the state of one object in the group instantaneously determines the state of other objects in the group.¹¹⁸

For example, two electrons might be in superposition states and entangled—one with 40% of the spin-down probability and 60% of the spin-up probability, and the other with 70% spin-down and 30% spin-up. If the first electron is observed and found spinning upward, the superposition state of the second electron will instantaneously collapse. Without a direct observation on the second electron, its state is determined spinning downward. Like superposition, entanglement has no explanation in classical physics, but it is essential to enabling quantum computing and networking.¹¹⁹

Appendix B. NQI Act-Funded R&D Centers¹²⁰

In February 2019, NSF issued a Program Solicitation for Quantum Leap Challenge Institutes (QLCI), which are "large-scale interdisciplinary research projects that aim to advance the frontiers of quantum information science and engineering." Research at these institutes would focus on topics such as quantum computing, networking, and sensing. According to NSF, the program is "consistent with the scope of NSF multidisciplinary centers for quantum research and education" as authorized and funded in the NQI Act.¹²¹ NSF thereafter awarded grants to create and support five QLCI, as shown in Table B-1.

In January 2020, DOE's Office of Science issued a Funding Opportunity Announcement (FOA) for the creation of National Quantum Information Science Research Centers (NQISRCs), which would "accelerate the transformational advances in basic science and quantum-based technology needed to assure continued U.S. leadership" in QIST.¹²² Since then, DOE has funded five NQISRCs, each led by a DOE national laboratory, as shown in Table B-2.¹²³ The goal of the NQISRCs is "to create and to steward the ecosystem needed to foster and facilitate advancement" of QIST.¹²⁴ Scientists and engineers at the centers work on designing and building (1) powerful quantum computer, (2) unhackable communication networks, (3) ultrasensitive instruments and sensors, and (4) groundbreaking new materials.¹²⁵