The hype around quantum computing has grown exponentially — forgive the math pun — as of late, even as good old ones-and-zeroes-based artificial intelligence has had its world-changing moment in the sun. The power, promise, and quandary of quantum computing are all contained in the difference between a quantum computer and a standard one. Whereas even the most powerful supercomputer does its work through a binary system of ones and zeroes, a quantum computer programs the subatomic state. In that state, mere particles are a platform for computation, allowing for an almost infinitely more powerful, speedy, and sophisticated series of calculations. The quantum computers that might follow from that innovation, some say, can do practically anything: They’ll solve climate change, and make modern cryptography obsolete. They might revolutionize drug discovery, or make gene editing as easy as a simple cardiogram. They could even allow you to witness the age of dinosaurs or the crucifixion of Jesus Christ as they really happened. (Okay, that last one was from a cable miniseries, but you get the point.) Recent years have seen companies including Google and a university in China claim to have reached “quantum supremacy,” or the demonstration of capabilities far beyond that of a “classical” computer; this year’s second annual Quantum World Congress claimed to bring a “quantum-ready future into focus.” But what does that even mean? How close are we to living in a world where everything from cybersecurity to medicine is utterly transformed by that revolution in how computers work at a subatomic level? “The people who need to raise huge amounts of venture capital or government funding have this enormous interest in making it appear like this is all going to happen next year,” says Scott Aaronson, the director of the Quantum Information Center at the University of Texas at Austin. “I spend a lot of my time both arguing against people who claim that quantum computing is going to revolutionize everything next year, and also against the people who say that it's impossible.” You don’t have to get bogged down in the details of physics or mathematics to see why quantum computing could be a boon, or danger, to society. As early as 1994, the physicist Peter Shor showed that quantum computers could theoretically break almost any code known to man, eventually leading the National Institute of Standards and Technology to hold a worldwide contest to develop “quantum-proof” new systems. Aaronson says quantum technology could someday simulate complicated scientific problems, leading to breakthroughs in battery and chemical technology. And, of course, quantum computers could help solve long-standing questions in particle physics, the very field that makes them possible. Before quantum computers do all that, however, they have to do something a little more prosaic: Actually beat their “classical” counterparts at anything useful at all. “A huge amount of the recent investment in quantum computing has been driven by what we could we could generously call ‘aspirational quantum algorithms,’” Aaronson said. “Conceivably, they would exponentially outperform a classical computer. Will they actually do that? Well, you know, who has any idea. But no one can prove that they won't.” Getting quantum computers to that point depends in part on the way the systems are built and maintained — the conditions under which they maintain programmability are so fragile that IBM’s quantum computers, for example, need to be held at a temperature a hundredth of a degree above absolute zero, although methods for dealing with “quantum decoherence” vary. Physicist Wesley Campbell leads a group at the University of California Los Angeles researching “trapped-ion” quantum systems, where the delicate environment required to sustain those systems is created by confining those ions to a vacuum. He said that despite the extent to which this research is already a boon to physics, he expects it to be a long time before it has any real practical application. “Companies used to do R&D, and basically now they just do D,” Campbell said. “All of quantum computing right now is still R.” Luckily for quantum mavens, governments across the world are eager to give them a leg up in that department. Here in the U.S., the National Quantum Initiative Act was signed into law in 2018, authorizing more than $1 billion for quantum-related research and standing up new quantum-focused offices across various federal agencies. That act expired on Sept. 30 but is widely expected to be re-authorized this Congress, and last year’s CHIPS and Science Act authorized its own slate of pro-quantum funding. Europe isn’t lagging on this front either, authorizing its own €1 billion research project to stake a claim in the quantum race. The nascent state of quantum computing research means that there’s plenty up for grabs for any nation with the brainpower and cash to invest in it.
| 
