SAN FRANCISCO — The world’s leading technology companies, from Google to Alibaba in China, are racing to build the first quantum computer, a machine that would be far more powerful than today’s computers.
This device could break the encryption that protects digital information, putting at risk everything from the billions of dollars spent on e-commerce to national secrets stored in government databases.
An answer? Encryption that relies on the same concepts from the world of physics. Just as some scientists are working on quantum computers, others are working on quantum security techniques that could thwart the code-breaking abilities of these machines of the future.
It is a race with national security implications, and while building quantum computers is still anyone’s game, China has a clear lead in quantum encryption. As it has with other cutting-edge technologies, like artificial intelligence, the Chinese government has made different kinds of quantum research a priority.
“China has a very deliberate strategy to own this technology,” said Duncan Earl, a former researcher at Oak Ridge National Laboratory who is president and chief technology officer of Qubitekk, a company that is exploring quantum encryption. “If we think we can wait five or 10 years before jumping on this technology, it is going to be too late.”
Quantum computing is based on quantum mechanics, the science that explains the strange behavior exhibited by extremely small particles of matter.
With traditional computers, transistors store “bits” of information, and each bit is either a 1 or a 0. Those are the fundamental slices of data that tell a computer what to do.
When some types of matter are extremely small or extremely cold, they behave differently. That difference allows a quantum bit, or qubit, to store a combination of 1 and 0. Two qubits can hold four values at once. As the number of qubits grows, a quantum computer becomes exponentially more powerful.
Like quantum computing, quantum encryption relies on the nonintuitive behavior of very small objects. The codes that keep data secret are sent by photons, the tiniest particle of light. With the right equipment it is easy to tell if they have been tampered with, not unlike the seal on an aspirin bottle. If carried out properly, the technique could be unbreakable.
There is no guarantee that a viable quantum encryption network could be built over long distances. But if it does happen, China’s willingness to experiment and put government, academic and commercial resources behind the effort could have a big payoff.
The country has invested tens of millions of dollars building networks that can transmit data using quantum encryption. Last year, a Chinese satellite named Micius, after an ancient philosopher, managed a video call between Beijing and Vienna using quantum encryption. A dedicated quantum communication network between Beijing and Shanghai was also put into operation last year, after four years of planning and construction.
A quantum research facility at the University of Chicago, which is exploring devices, known as quantum repeaters, that could extend the range of encryption.CreditLyndon French for The New York Times
For now, quantum encryption works only over a limited distance. The satellite link between Beijing and Vienna stretched this limit to a record 4,630 miles. On the ground, using optical fiber lines, the ceiling is about 150 miles.
Among China’s investments in quantum encryption, the Micius satellite has received the most attention. The University of Science and Technology of China, the government-backed university that helped launch Micius, led the construction of the ground network, which spans about 1,200 miles — perhaps a hint of aspirations for drastic improvement.
The governments of Anhui and Shandong Provinces, through which the fiber-optic network passes, together invested $80 million in the project. Like all major infrastructure projects in China, the plans have had high-level support from the Chinese government.
This main line is being extended to other cities and regions. The goal by 2030 is a Chinese-built network for sharing quantum encryption keys across the globe.
Some security experts question the effectiveness of quantum encryption. Because it is so new, it has not been put through anywhere close to the rigorous testing that would give it a stamp of approval from skeptical cryptographers.
But Chao-Yang Lu, a professor of physics at the University of Science and Technology of China, said the Beijing-Shanghai quantum network was a significant upgrade.
With communications sent by traditional means, eavesdroppers can intercept the data stream at every point along a fiber-optic line. A government could tap that line just about anywhere. Quantum encryption cut the number of vulnerable spots in the Beijing-Shanghai line to just a few dozen across 1,200 miles, Professor Lu said.
“We admit that it’s an intermediate solution,” he said. “It’s not the final solution. But it’s already a huge improvement in terms of security.”
In the United States, the government and industry have viewed quantum encryption as little more than a science experiment. Instead, researchers have focused on using ordinary mathematics to build new forms of encryption that can stand up to a quantum computer. This technology would not require new infrastructure.
But now, spurred by activity in China and recent advances in quantum research, some in the United States are playing catch-up.
Qubitekk, a Southern California start-up, is working to secure power grids in Tennessee using the technology. A second start-up, Quantum Xchange, is building a quantum encryption network in the Northeast, hoping to serve Wall Street banks and other businesses. Researchers at Stony Brook University on Long Island are preparing a third venture.
Small start-ups like Qubitekk are unlikely to match the millions of dollars in infrastructure already created in China for quantum encryption. But many experts believe the more important work will happen in research labs, and the Department of Energy is funding a test network in Chicago that could eclipse the kind of systems deployed in China.
The Los Alamos and Oak Ridge National Laboratories are working with Qubitekk to secure power grids with quantum technology, and Quantum Xchange is moving equipment into 60 Hudson Street, the old Western Union telegraph hub, which now serves as an internet hub for Lower Manhattan.
Quantum Xchange is building a quantum encryption link between Manhattan and Newark, with plans to connect big banks operating in the two cities. Eventually, it hopes to extend this network up and down the East Coast.
At places like the University of Chicago, researchers hope to go a step further, exploring what are called quantum repeaters — devices that could extend the range of quantum encryption.
“We’re not there yet,” said David Awschalom, a professor at the University of Chicago who oversees much of the university’s quantum research. “But I am confident this will happen in the next couple of years.”
Quantum communication techniques require new hardware. This includes vast networks of fiber lines — and perhaps satellites — as well as specialized devices capable of detecting individual photons of light.
As Qubitekk worked on quantum encryption networks, it could not obtain the special light detectors it needed to do the work. The start-up originally bought detectors from a small manufacturer in New Jersey, Princeton Lightwave. But in April, this lone American manufacturer handed the detector business over to a company in China, RMY, and Qubitekk’s supply line ran dry.
RMY has promised hardware to Qubitekk but recently told it that, because of production issues, additional detectors won’t be available until March.
Small companies in Europe are selling somewhat similar detectors, and labs across the globe are developing a more advanced type of hardware. But for now, supplies, particularly in the United States, are slim.