New cryptography must be developed and deployed now, even if quantum threats are a decade away

Though the arrival of a general-purpose quantum computer would have a major detrimental impact on cryptography, there are many potential benefits of pursuing progress in the field.  Results from research in this space have already helped advance progress in physics, for example, in areas such as quantum gravity, and in computer science by motivating or informing improvements in classical algorithms. Quantum computing, like few other foundational research areas, has the potential to greatly speed up computing for certain applications, which makes supporting a robust research community in the U.S. of strategic value, the report says.

“There has been remarkable progress in the field of quantum computing, and the committee doesn’t see a fundamental reason why a large, functional quantum computer could not be built in principle,” said Mark Horowitz, Yahoo! Founders Professor at Stanford University and chair of the committee. “However, many technical challenges remain to be resolved before we reach this milestone.”

The report identifies significant challenges that lie ahead in the areas of building new algorithms, software, control technologies, and hardware concepts. One of the challenges is the need to correct the errors in a quantum system, without which it is unlikely that a highly complex quantum program would ever run correctly on the system.  However, these algorithms incur significant costs, so in the near term quantum computers are likely to be error-prone, the report said.

Another significant challenge pointed out by the committee is that while a quantum computer can use a small number of qubits to represent a large amount of data, there is currently no rapid method to convert a large amount of classical data into a quantum state.  Unless a new method is developed for efficiently transferring the data to a quantum computer, the process could reduce or minimize the speedup that is possible overall for a quantum computation on a large dataset.

One of the key findings in the report is that it is still too early to be able to predict the time horizon for a practical quantum computer.  The committee identified several approaches for monitoring progress in the near term and long term, including metrics and milestones.  The report also found that research and development into practical commercial applications of near-term quantum computers— expected to be much smaller and more error-prone than those that could  defeat public-key encryption – is critical for the field.  The results of this work will have a profound impact on the rate of development of large-scale quantum computers and on the size and robustness of the commercial market.

Additionally, the current research on quantum computing has clear implications for national security, the report said. Any entity that has a large-scale quantum computer could break today’s cryptography to read intercepted communications or stored data.  While the U.S. has historically played a leading role in developing quantum technologies, quantum information science and technology is now a global field, and many other nations have made large resource commitments, the report says. Continued support from the U.S. to this field is imperative if the country wants to maintain its leadership position.

The study was sponsored by the Office of Director of National Intelligence.