Quantum Computing Advance Begins New Era, IBM Says (nytimes.com) 28
Because of their intrinsic ability to consider many possibilities at once, quantum computers do not have to be very large to tackle certain prickly problems of computation, and on Wednesday, IBM researchers announced that they had devised a method to manage the unreliability in a way that would lead to reliable, useful answers. From a report: "What IBM showed here is really an amazingly important step in that direction of making progress towards serious quantum algorithmic design," said Dorit Aharonov, a professor of computer science at the Hebrew University of Jerusalem who was not involved with the research. While researchers at Google in 2019 claimed that they had achieved "quantum supremacy" -- a task performed much more quickly on a quantum computer than a conventional one -- IBM's researchers say they have achieved something new and more useful, albeit more modestly named. "We're entering this phase of quantum computing that I call utility," said Jay Gambetta, a vice president of IBM Quantum. "The era of utility." A team of IBM scientists who work for Dr. Gambetta described their results in a paper published on Wednesday in the journal Nature.
[...] The IBM researchers in the new study performed a different task, one that interests physicists. They used a quantum processor with 127 qubits to simulate the behavior of 127 atom-scale bar magnets -- tiny enough to be governed by the spooky rules of quantum mechanics -- in a magnetic field. That is a simple system known as the Ising model, which is often used to study magnetism. This problem is too complex for a precise answer to be calculated even on the largest, fastest supercomputers. On the quantum computer, the calculation took less than a thousandth of a second to complete. Each quantum calculation was unreliable -- fluctuations of quantum noise inevitably intrude and induce errors -- but each calculation was quick, so it could be performed repeatedly.
[...] The IBM researchers in the new study performed a different task, one that interests physicists. They used a quantum processor with 127 qubits to simulate the behavior of 127 atom-scale bar magnets -- tiny enough to be governed by the spooky rules of quantum mechanics -- in a magnetic field. That is a simple system known as the Ising model, which is often used to study magnetism. This problem is too complex for a precise answer to be calculated even on the largest, fastest supercomputers. On the quantum computer, the calculation took less than a thousandth of a second to complete. Each quantum calculation was unreliable -- fluctuations of quantum noise inevitably intrude and induce errors -- but each calculation was quick, so it could be performed repeatedly.