Peering into his cabinet of curiosities on a recent spring day, Bob Willett, a scientist at Bell Labs in Murray Hill, N.J., nimbly plucked a tiny black crystal from the shelves and slid it under a microscope. “This is a good one,” he promised.
A pattern of circuit leads radiated outward on the crystal’s surface like the rays of a square sun. The product of decades of trial and error by Willett and his collaborators, it was made from a flake of gallium arsenide so pure, he said, that electrons inside could sense one another’s presence across vast micrometers of distance. When the crystal is magnetized and cooled to a fraction of a degree, the electrons unite, forming a peculiar quantum state that could be the makings of an unimaginably powerful computer.
Willet is attempting to harness that state to build a “topological qubit” — an information-storing device analogous to the bits that make up ordinary computers, only far more complex and potent. Qubits are the basic building blocks of a quantum computer, an undeveloped technology devised in the early 1980s. Unlike that of ordinary bits, the power of qubits grows exponentially with their number. For many tasks, a comparatively small quantum computer — made up of only 100 qubits — would outperform the world’s best supercomputers and usher in a new level of computing power for humanity.
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