IBM ResearchĪdditionally, each step of a calculation has a significant chance of introducing error. IBM has made 18 quantum computers available for use online, and all grapple with errors. IBM researchers Hanhee Paik (left) and Sarah Sheldon (right) work on a quantum computer that is cooled by a hanging dilution refrigerator. If a single atom that represents a qubit gets jostled, the information the qubit was storing is lost. Errors can creep in as qubits interact with their environment, potentially including electromagnetic fields, heat or stray atoms or molecules. They are made from sensitive substances such as individual atoms, electrons trapped within tiny chunks of silicon called quantum dots, or small bits of superconducting material, which conducts electricity without resistance. Jostling one of the bit’s atoms won’t change the overall magnetization of the bit and its corresponding value of 0 or 1.īut quantum bits - or qubits - are inherently fragile. That large group of atoms offers a built-in redundancy that makes classical bits resilient. In a classical hard drive, for example, the data are stored in bits, 0s or 1s that are represented by magnetized regions consisting of many atoms. Fragile qubitsĬonventional computers - which physicists call classical computers to distinguish them from the quantum variety - are resistant to errors. If errors aren’t brought under control, scientists’ high hopes for quantum computers could come crashing down to Earth. And the quantum calculations scientists envision are complex enough to be impossible to redo by hand, as Johnson did for Glenn’s ambitious flight. That kind of power could speed up the discovery of lifesaving drugs or help slash energy requirements for intensive industrial processes such as fertilizer production.īut there’s a catch: Unlike today’s reliable conventional computers, quantum computers must grapple with major error woes. The machines could calculate the properties of intricate molecules or unlock the secrets of complicated chemical reactions. 28).Ĭurrent versions are relatively wimpy, but with improvements, quantum computers have the potential to search enormous databases at lightning speed, or quickly factor huge numbers that would take a normal computer longer than the age of the universe. Scientists expect quantum computers to one day solve problems vastly too complex for standard computers ( SN: 7/8/17, p. But the era of a new breed of powerful calculator is dawning. Luckily, modern computers are very reliable. Quantum computers of the future will be highly susceptible to mistakes, so to make their calculations trustworthy, the machines will need to correct their own errors. astronaut John Glenn was wary of making his 1962 voyage into space until mathematician Katherine Johnson (left) checked and confirmed the flight path calculations made by the IBM 7090 computer (one shown, right). If NASA had been relying on a computer that glitchy, Glenn would have been right to be anxious. For complex computations, a small probability for error can quickly generate a nonsense answer. Now, multiply that error rate by the billions or trillions of calculations per second possible in a typical modern computer. But once every 100 calculations, it flubs: 1+1=3. Most of the time the computer tells you 1+1=2. Imagine a computer with 99 percent accuracy. 131).Ī computer that is even slightly error-prone can doom a calculation. “If she says they’re good,” Glenn reportedly said, “then I’m ready to go.” Johnson determined that the computer, an IBM 7090, was correct, and Glenn’s voyage became a celebrated milestone of spaceflight ( SN: 3/3/62, p. The astronaut requested that mathematician Katherine Johnson double-check the computer’s numbers, as recounted in the book Hidden Figures. But Glenn wasn’t willing to entrust his life to a newfangled machine that might make a mistake. It was 1962, early in the computer age, and a room-sized machine had calculated the flight path for his upcoming orbit of Earth - the first for an American. Astronaut John Glenn was wary about trusting a computer.
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