WASHINGTON — For years, quantum computing, which leverages the difficult, and, to many, spooky science of quantum mechanics, has been a subject mostly of interest to the technical elite. Yet as scientists and now policymakers point to the rapid progress that China is making in the field, it’s the intelligence community that appears to be the most alarmed.

“Our folks in the intelligence community are completely worried about this,” said Will Hurd, a Republican congressman from Texas and a former CIA officer who has criticized President Trump for his failure to defend the nation’s spy agencies.

Earlier this year, the Trump administration hosted an event focused on quantum science with major companies in attendance, and has demonstrated an appetite for confronting China on issues like trade and economic espionage. Yet researchers working in the field argue that much more needs to be done in advance of China’s progress.

For a great majority of the population, the science behind quantum computing is difficult to comprehend. A quantum computer, like a standard computer, encodes information as bits to process information, but it does so by manipulating the physical properties of the quantum bits, or qubits, allowing them to store and process an exponentially larger amount of data in a far shorter time period.

“Quantum computing is not only a new way to do computing, but is really a new transformation in technology,” said Alessandro Curioni, IBM’s vice president in Europe and the director of an IBM Research Lab in Zurich. “It will make problems that were previously unsolvable … practical.”

The most practical application, and the one of concern to the national security community, regards encryption. However, Curioni says it might take thousands or even a million qubits to break modern encryption keys, a development that could be “decades away.”

Google unveiled its groundbreaking 72-qubit quantum computer, Bristlecone, in March 2018, though scientists are still working to prove today’s product is faster than a modern supercomputer.

Yet if quantum computing’s applications are realized, as many scientists working in the field claim they will be, the national security implications are numerous.

One of the biggest and most widely circulated concerns over China’s quantum computing work is that it could enable powerful new machines to break through the layer of security protecting online transactions around the world, thereby exposing highly sensitive information.

According to one recently retired national security official focused on emerging threats presented by advanced technology, China is on track to be 20 years ahead of the United States in the not-too-distant future. Another national security official said the United States is currently scrambling to defend itself, hoping to find foolproof ways to protect its everyday communications in the worst case.

Congress appears to be taking note. “China is eating our lunch on quantum,” said one congressional staffer. Lawmakers tasked with intelligence and national security issues will be focusing on China in coming months, hoping to inspire quicker progress on the U.S. side.

“A powerful quantum computer will be dangerous to our connected world,” said one senior national security official. “It’s not too early by any stretch to be thinking about quantum resistance,” or ways to defend ourselves.

Yet sufficiently powerful quantum computer capable of solving unthinkably complex equations and shattering some forms of modern encryption may still be years or even decades away.

And critics of the field argue there’s also quantum hype, since no one yet has been able to prove they’ve built a quantum computer with practical applications.

Writing last month in IEEE Spectrum, theoretical physicist Mikhail Dyakonov described quantum computing as “something of a self-perpetuating arms race.” Noting that practical applications for quantum computers, even in the more optimistic scenarios, are a long way off, Dyakonov offered an even more pessimistic assessment of a quantum timeline. “I belong to a tiny minority that answers, ‘Not in the foreseeable future,’” he wrote.

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