Google's Quantum Echoes algorithm closes gap to real-world quantum applications

Google’s Quantum AI team has announced a significant breakthrough, claiming the first-ever verifiable quantum advantage on hardware using their Willow quantum chip and a new algorithm called Quantum Echoes. The research, published in the journal Nature on 22 October 2025, marks a step toward practical, real-world applications for quantum computing, particularly in fields like drug discovery and materials science.

The experiment demonstrated that the Quantum Echoes algorithm runs approximately 13,000 times faster on the Willow chip than the best classical algorithm could on one of the world's fastest supercomputers for the same task.

Today, we’re announcing a major breakthrough that marks a significant step forward in the world of quantum computing. For the first time in history, our teams at @GoogleQuantumAI demonstrated that a quantum computer can successfully run a verifiable algorithm, 13,000x faster than…

— Google AI (@GoogleAI) October 22, 2025

The Importance of Verifiable Quantum Advantage

This milestone moves past the concept of "quantum supremacy," which Google first claimed in 2019 by solving a highly complex, but not inherently useful, mathematical problem. Verifiable quantum advantage is a different class of achievement. It means the result produced by the quantum computer is not only beyond the capability of classical supercomputers but is also repeatable and confirmable, either by other quantum systems of similar quality or through validation against real-world physics experiments.

This repeatability transforms the quantum computer from a powerful but often inscrutable calculator into a tool capable of producing trustworthy scientific results

Hartmut Neven, Founder and Lead of Google Quantum AI, and Vadim Smelyanskiy, Director of Quantum Pathfinding, stated that this repeatable, beyond-classical computation is the basis for scalable verification, which is crucial for moving quantum computers closer to becoming practical tools.

Quantum Echoes: A Molecular Ruler

The new algorithm, formally an out-of-time-ordered correlator (OTOC), is called Quantum Echoes because it functions like a highly advanced time-reversal experiment. The process works by:

1. Sending a signal into the quantum system (the qubits on the Willow chip).
2. Perturbing a single qubit.
3. Precisely reversing the system's evolution to "listen" for a quantum echo.

This quantum echo gets amplified by constructive interference, which makes the measurement highly sensitive. The algorithm’s utility lies in its ability to learn the structure of natural systems, ranging from molecules to magnets.

In a proof-of-principle experiment, Google collaborated with the University of California, Berkeley, to apply Quantum Echoes to study two molecules with 15 and 28 atoms. The results aligned with those from traditional Nuclear Magnetic Resonance (NMR) methods, the science behind MRI technology, but also revealed structural information that NMR typically cannot access. Researchers refer to this new technique as a "molecular ruler" because it can measure longer distances within molecules than current methods, offering scientists a powerful new lens into chemical structures.