Using a 65-qubit Willow superconducting processor, Google researchers measured how quantum information spreads and refocuses within an entangled system . This technological leap in quantum computing was called Quantum Echoes.

Unlike the 2019 Sycamore experiment, which claimed “quantum supremacy” for completing a random-number task faster than any supercomputer, Quantum Echoes was not a speed race but a test of understanding. Scientists measured out-of-time-order correlators (OTOC) — tiny echoes that reveal how disturbances travel through a network of qubits.

The method resembles giving a material a microscopic “poke,” reversing time evolution, and listening for the returning echo. The echo’s strength reveals how quickly information disperses, offering insight for chemistry, materials sc

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