Quantum computers are still in their infancy. Presently limited to 100 or so error-prone qubits, the quantum equivalents to classical bits, they are far from supreme calculating machines that are capable of exactly simulating chemical reactions and more. Quantum theorists and experimenters are working within these constraints to find feasible tasks for their devices to show an advantage over the performance of classical computers.
“Different systems scramble things in different ways,” says Shenglong Xu, a quantum information theorist at Texas A&M University, who was not involved with the Google research. “How the information gets processed tells us about the nature of the system.” Insight from scrambling could even provide details that would allow quantum technologists to achieve precise molecular simulations with their machines.
In a preprint paper, posted online in June, the Google team reported the most in-depth measurement of information scrambling to date, which was achieved with their 105-qubit Willow chip. They repeatedly scrambled the information, made a small adjustment and reversed the process, unscrambling the information. (Google dubbed the protocol “Quantum Echoes,” a reference to the echo of the repetitive unscrambling process.) The team’s measurement was so complex, in fact, that using current algorithms a classical supercomputer would be far slower than Willow. The results were published today in the journal Nature.
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