Now, their attempt to reconcile quantum information and gravity has revealed a surprising connection: new types of error-correcting codes for proposed quantum computers have emerged from tools developed to study quantum gravity.įor decades, physicists have aspired to compute using quantum bits, or qubits, in place of the bits used by "classical" computers.
Information seems abstract, but it plays surprisingly substantive roles in physics for example, trying to understand what happens to the information content of matter that falls into a black hole has forced theorists to question their views of relativity and quantum mechanics. Once that nuclear science barrier was passed in 1942, it led to technologies like nuclear power and atomic bombs ( SN: 11/29/17).New types of error-correcting codes for proposed quantum computers have emerged from tools developed to study quantum gravity. “It’s like achieving criticality with fission,” Schuster says. In a full-fledged example, scientists would detect and correct errors multiple times on the fly.ĭemonstrating quantum error correction is a necessity for building useful quantum computers. Instead, they fixed errors after the computer was finished. While the computer detected the errors that arose, the researchers didn’t correct the mistakes and continue on with computation.
HARLOW QUANTUM ERROR CORRECTION FULL
However, the team didn’t quite complete the full process envisioned for error correction. Thanks to those efforts, the new logical qubit had a lower error rate than that of the most flawed components that made it up, says quantum physicist Christopher Monroe of the University of Maryland in College Park and Duke University. The researchers also designed sequences of operations so that errors don’t multiply uncontrollably, what’s known as “fault tolerance.” To make their logical qubit, the researchers used a technique called a Bacon-Shor code, applying it to qubits made of ytterbium ions hovering above an ion-trapping chip inside a vacuum, which are manipulated with lasers.
Future quantum computers could make calculations using logical qubits in place of the original, faulty qubits, repeatedly checking and fixing any errors that crop up. In the new study, four additional, auxiliary qubits interfaced with the logical qubit, in order to identify errors in its data. (The Harry Potter villain kept his soul safe by concealing it in multiple objects called Horcruxes.) “If a piece of it goes missing, you can reconstruct it from the other pieces, like Voldemort,” says quantum physicist David Schuster of the University of Chicago, who was not involved with the new research. That allows researchers to check and fix mistakes in the data. In a logical qubit, information is stored redundantly. But now that scientists have shown that they can keep errors under control, he says, “there’s nothing fundamentally stopping us to build a useful quantum computer.” To do complex calculations, scientists will have to dramatically scale up the number of qubits in the machines. Still, that path remains a long one, Hensinger says.
“This is a key demonstration on the path to build a large-scale quantum computer,” says quantum physicist Winfried Hensinger of the University of Sussex in Brighton, England, who was not involved in the new study. Scientists used nine qubits to make a single, improved qubit called a logical qubit, which, unlike the individual qubits from which it was made, can be probed to check for mistakes. But without a mechanism for fixing the computers’ mistakes, the answers that a quantum computer spits out could be gobbledygook ( SN: 6/22/20).Ĭombining the power of multiple qubits into one can solve the error woes, researchers report October 4 in Nature. The fragile quantum bits, or qubits, that make up the machines are notoriously error-prone, but now scientists have shown that they can fix the flubs.Ĭomputers that harness the rules of quantum mechanics show promise for making calculations far out of reach for standard computers ( SN: 6/29/17). Mistakes happen - especially in quantum computers.
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