The biggest flipping challenge in quantum computing
To realize their dreams, developers must learn to tame the noise that jostles their machines’ delicate quantum bits.
In October 2019, researchers at Google announced to great fanfare that their embryonic quantum computer had solved a problem that would overwhelm the best supercomputers. Some said the milestone, known as quantum supremacy, marked the dawn of the age of quantum computing. However, Greg Kuperberg, a mathematician at the University of California, Davis, who specializes in quantum computing, wasn’t so impressed. He had expected Google to aim for a goal that is less flashy but, he says, far more important.
Whether it’s calculating your taxes or making Mario jump a canyon, your computer works its magic by manipulating long strings of bits that can be set to 0 or 1. In contrast, a quantum computer employs quantum bits, or qubits, that can be both 0 and 1 at the same time, the equivalent of you sitting at both ends of your couch at once. Embodied in ions, photons, or tiny superconducting circuits, such two-way states give a quantum computer its power. But they’re also fragile, and the slightest interaction with their surroundings can distort them. So scientists must learn to correct such errors, and Kuperberg had expected Google to take a key step toward that goal. “I consider it a more relevant benchmark,” he says.