Google's Quantum AI team announced a major breakthrough earlier this year.The new generation of "Willow" quantum chipsA new algorithm called "Quantum Echoes" has been successfully run, achieving the world's first "verifiable quantum supremacy".
Google emphasized that the algorithm runs about 13000 times faster on the Willow chip than the world's fastest classical supercomputer. This means that for the first time, quantum computing can empirically surpass the limits of traditional computing on specific algorithms. This is regarded as an important milestone in the practical application of quantum computers.
Based on the research of 2025 Nobel Prize winner Michel Devoret
It is worth noting that the theoretical basis and hardware foundation of this breakthrough technology are closely related to the research results that just won the 2025 Nobel Prize in Physics.
Michel Devoret, one of the award winners, is currently the Chief Scientist, Quantum Hardware at Google Quantum AI and a professor of applied physics at Yale University.
Google noted that Professor Michel Devoret and his co-awardees, John Martinis (former head of hardware at Google Quantum AI) and John Clarke, pioneered research in the 1980s on superconducting quantum circuits, demonstrating that quantum effects at macroscopic scales can be controlled and measured. Their superconducting circuits, built using Josephson junctions, are the technological foundation for the superconducting qubits in Google's current Willow chip.
Hartmut Neven, founder of Google Quantum AI, said: "Quantum Echoes not only demonstrates a leap in hardware performance, but also demonstrates the importance of fundamental research like that of Michel Devoret. It is these theoretical achievements that are truly moving quantum technology towards practical applications."
"Quantum Echoes": Using "time reversal" to listen to quantum echoes
According to a study published by Google in the journal NatureResearchThe core technology of the "Quantum Echoes" algorithm is to execute an algorithm called "out-of-order time correlator" (OTOC) on the Willow chip.
Vadim Smelyanskiy, a Google research scientist, explained that this technology is like an advanced "sonar." Researchers input a precise signal into the quantum system on the Willow chip, then "reverse" its evolution and "listen" to the "quantum echo" that returns, analyzing subtle changes in the signal.
Google explains that these echoes are amplified through a phenomenon called constructive interference, making their measurements extremely sensitive. This mechanism can precisely reveal the evolution of quantum states, thereby describing the internal structure of particles or molecules in natural systems.
Achieving a "verifiable" advantage, simulating molecular structures like "seeing the name on a ship's hull"
Google emphasized that the biggest difference between this achievement and the "quantum supremacy" demonstrated in 2019 is "verifiability."
The 2019 Random Circuit Sampling (RCS) experiment only demonstrated that quantum computers can accomplish "specific tasks" that supercomputers cannot. However, the "Quantum Echoes" experiment demonstrates an algorithm with real-world physical implications. Its results are not only reproducible but can also be cross-referenced with other quantum computers of the same level, laying the foundation for practical tools.
Google described that in the past, when using sonar to detect shipwrecks on the seabed, only a blurry image of "there is something there" might be obtained; and the "Quantum Echoes" technology is like allowing scientists to "directly see the name plate on the hull."
In a collaborative experiment with the University of California, Berkeley, the team used this algorithm to successfully simulate the structures of molecules containing 15 and 28 atoms. The results were not only consistent with traditional nuclear magnetic resonance (NMR) experiments, but also revealed molecular details that were previously difficult to observe.
The high stability of the Willow chip is the key
Key to this achievement lies in the low error rate and high stability of the Willow chip. Yu Chen, Director of Google Quantum AI Hardware, noted that the Willow chip achieves 99.97% single-qubit gate fidelity and 99.88% entanglement gate fidelity across its 105-qubit array, all while operating at exceptionally high speeds.
The algorithm runs on the Willow chip with such precision and complexity that Google says the project performed a trillion measurements, a significant fraction of the total number of measurements ever performed by any quantum computer.
Google stated that this technology could be applied in the future to areas such as drug development, materials science, and even quantum material design. Google is currently advancing its hardware development blueprint, with the next phase (Milestone 3) aiming to achieve long-lived, error-correcting "logical qubits."
