China’s investing billions in quantum R&D, but is Beijing making some bad bets?

WASHINGTON — Who is winning the quantum race? By many measures, that would be China. But if quantum physics holds just one lesson for daily life, it’s that reality is hard to measure.

That doesn’t stop people from trying. When the Australian Strategic Policy Institute surveyed the most influential published scholarship, for example, it found China led in three of four aspects of quantum science. By another measure, Mitchell Institute expert Heather Penney warned in a recent report, “China now holds twice as many quantum patents as the United States,” although not all patents are anywhere near equal.

How about comparing cold, hard cash? The Chinese government’s investments in quantum may amount to more than triple the US’s, Penney wrote, citing figures by McKinsey & Company of over $15 billion in public announcements versus the US’s $3.7 billion. Or, she acknowledged a sentence later, maybe Beijing has only invested $4 billion. It’s unclear.

That’s because Chinese government spending is notoriously opaque. “[Such] conflicting reports of funding levels are not unusual in China,” wrote a RAND quantum race expert, Edward Parker. “The PRC government often announces ambitious (and often highly politicized) spending goals, and it is not uncommon for these goals to go unmet … [so] we cannot determine whether the PRC total is higher or lower.”

But Beijing’s blurry budgeting is just the beginning of the indeterminacy problem in the quantum race, which makes Schrödinger’s dead-or-alive cat problem look almost straightforward. It turns out that “quantum” is really a whole array of related technologies, with different applications and potential, rather than a single thing. The US and China are prioritizing different aspects — and Washington is betting that Beijing’s bets are bad ones.

“The Chinese are taking an all of the above approach; there’s nothing in quantum they have ruled out,” Parker told Breaking Defense. “The US approach is also quite diversified … but the US has ruled out a few specific technologies which the Chinese are leaning very heavily into, namely quantum key distribution and quantum radar.”

Sensing: Quantum Radar

Consider “quantum radar,” touted by some Chinese sources as an up-and-coming counter to American stealth jets. Penney wrote that “China has openly messaged its quantum radar as a jam-resistant counter-stealth capability,” not just in academic studies but even in airshow marketing materials.

Normal radar works by bouncing radio waves off aircraft and calculating the target’s position from the echoes reflected back; stealth absorbs and redirects those radio waves so the enemy radar doesn’t receive enough reflected energy to work with. Quantum radar, however, can in theory detect even weak reflections, because it’s far more sensitive.

Specifically, quantum radar exploits the fact that pairs of subatomic particles can become “entangled,” Penney and Parker explained. The sensor generates a bunch of entangled particles and sends out one particle of each pair to search, while keeping the other for reference. When a search particle hits a target and bounces off, it’s easier to find that faint reflection because the radar has the reference particle for comparison.

But many US experts see a lot of problems with the idea.

“Quantum radar sounds awesome. It’s actually pretty impractical,” said Penney, a former fighter pilot, at a briefing on her study. There’s no satisfactory way to store the reference particles the concept requires, she argued, or to check their status without breaking their entanglement, and even if you could, it’s not clear how any of this would turn into a militarily useful track of a target.

That skepticism reflects US consensus. “The US military has publicly identified quantum radar as impractical,” Park testified to the congressionally chartered US-China Commission on Thursday.

“You need just an incredibly large number of entangled photons and entangled photons are extremely difficult to generate,” he told Breaking Defense in a follow-up interview. “Even just storing a photon is not easy.” Then the quantum radar has to bring the reflected search particles and their entangled reference-particle counterparts back together for comparison, he said: “The timing and synchronization requirements are incredibly challenging.”

By contrast, the US and its allies have focused on different kinds of quantum sensors. Instead of relying on entanglement, which is easy to break, these sensors exploit the hypersensitivity of subatomic particles to detect subtle shifts in magnetism or gravity, with applications from navigating without GPS to hunting enemy submarines. While China could be working on such tech in secret, Parker found no evidence of “any comparable public operational tests.”

Of course, the US consensus could be wrong about which kind of quantum sensor works best. It’s not just the Chinese who are betting on quantum radar: Western researchers from France, Canada and Austria have also claimed promising results, noted Arthur Herman, director of the Quantum Alliance Initiative at the Hudson Institute, with one study claiming a 20 percent improvement over conventional radar.

“Twenty percent improvement doesn’t sound exactly like a breakthrough,” Herman acknowledged. “But as Edward Teller [the father of the H-bomb] used to say: ‘If the physics works, the technology will follow.'”

There’s truth in Teller’s maxim. But sometimes, as with America’s early Cold War experiments in atomic-powered airplanes and jeep-borne nuclear bombs, what’s technologically feasible isn’t always militarily practical. That problem is particularly pertinent to China’s other big bet in quantum science that the US defense consensus also disdains: quantum key distribution.

Communications: Quantum Key Distribution

“Spooky action at a distance.” That was Albert Einstein’s derisive description of quantum entanglement, the then-controversial idea that a pair of subatomic particles could become so cosmically co-dependent that changing one of them would change the other — however far apart they were, anywhere in the universe, instantaneously. Impossible, the great scientist scoffed.

Einstein, of course, was wrong. The 2022 Nobel Prize in physics honored scientists who proved “spooky action at a distance” experimentally in the 1970s and ’80s. And in 2017, a Chinese satellite named Micius, after the Confucian sage, used entangled particles to send messages for the first time between space and ground, an achievement hailed worldwide. Since then, China has launched a second such satellite — with even more planned in higher orbits — and built a 2,000-mile ground link between Beijing and Shanghai, all using the same principle of “quantum key distribution.”

The attraction of “QKD” for both military planners and China’s authoritarian elite is secrecy: In theory, it’s impossible for an unauthorized third party to intercept such a transmission. That’s because the “quantum keys” used to secure each message are subatomic particles so hypersensitive to outside stimuli that merely measuring one — which is necessary to know what information it encodes — will alter its state (i.e. the observer effect), scrambling the message before it can be read.

That’s great for security, not so great for communication. (It’s as if someone randomly changed every letter in an email: The reader will know something went wrong but not what the original text said). The enemy may not be able to read your QKD-encrypted messages, but they can easily keep you from reading them, either. And, especially in wartime, that may be damaging enough — which is why major militaries have dedicated electronic warfare units whose job is to disrupt communications.

“QKD is extremely fragile, so it is difficult to eavesdrop on a QKD signal, but it’s actually very easy to just jam it,” Parker told Breaking Defense. The Micius satellite only worked on moonless nights, for instance, because moonlight, let alone sunlight, would overwhelm the signal. Now imagine how easy it would be for a major nation’s electronic warfare forces to cause such interference deliberately.

As soon as an enemy listens in a QKD-encrypted transmission, agreed Penney, “the encryption is collapsed and you have to start the whole process over again.” So it’s not a valid military communications system, she told reporters: “It’s basically a stunt. … It’s not the direction the United States is going or wants our partners to go in.”

In fact, the National Security Agency issued a public advisory in 2020 that warned against the use of QKD or military or intelligence purposes. NSA cited not only the ease of jamming but other security vulnerabilities and the sheer expense of the specialized hardware required.

So, instead of building all-new QKD hardware, the US government approach to cybersecurity in the quantum era is to upgrade existing software with new, more robust encryption algorithms, known in the trade as Post-Quantum Cryptography (PQC).

“Our agency creates the keys, codes, and cryptography that ensures the underlying encryption of our nation,” said Gen. Paul Nakasone, the NSA director, in a Jan. 31 hearing before Congress. “We are developing those keys, codes, and, cryptography in partnership with NIST to ensure that our nation is safe from a quantum computer [hack].”

Of course, the Chinese could be right, and Nakasone wrong. “I think NSA does a public disservice by taking this extreme line,” said Herman. “Quantum-enabled cryptography — both QKD and photon key distribution, or PKS — works very well for certain kinds of security scenarios, while PQC does not. The future of quantum security should be a mix of both, instead of betting on software-based solutions only, as PQC does.”

“Why has China decided to invest billions in a QKD-based security infrastructure, including in space,” he asked, “when our most brilliant minds at NSA and NIST and RAND, it seems, know this is a dead end?”

For an authoritarian regime like China, however, megaprojects can be attractive precisely because they require so much work, regardless of the return on that investment. They’re an opportunity for bureaucratic empire-building and propaganda in a way smaller, more practical projects are not.

“It lends itself to large rollouts,” Parker said. “It requires a lot of hardware laydown, which from some perspectives is a bad thing because it’s very expensive and very disruptive and takes a lot of time, but from the perspective of national prestige it’s perhaps a good thing, because … the Chinese can say they’ve laid down thousands of kilometers of quantum key distribution network and they’ve launched two different quantum satellites, [which is] difficult for other countries to match.”

A second appeal of QKD to authoritarians, Parker added, is that Chinese leaders were deeply shaken by the Edward Snowden revelations of NSA’s hacking prowess. A hack-proof network that’s entirely made in China might be too tempting a pitch to resist.

That doesn’t necessarily make it a good plan. But, Parker said, “inherent to the nature of a more top-down, authoritarian society … there are fewer internal checks and balances that adjust away from misallocation of resources.”