Verifiable Milestone Quantum Echoes: Quantum Algorithm 13,000 Times Faster Than Supercomputer

The team at Google Quantum AI has designed an algorithm for quantum computers that, according to a study, significantly outperforms supercomputers for certain tasks for the first time.

It is not the first time that Google has claimed to have achieved quantum supremacy. This time, however, the claims are backed by verifiable research: According to a study published in the journal Nature, quantum computers using the specially developed Quantum Echoes algorithm can significantly outperform supercomputers in certain computational tasks—being up to 13,000 times faster in some cases. For the first time, this achieves a verifiable quantum advantage for a scientifically relevant computational task—a crucial difference from earlier, often criticized demonstrations.

The method is based on a so-called Out-of-Time-Order Correlator (OTOC) and was executed on Google’s 105-qubit processor Willow. According to the study, it was able to perform a complex quantum dynamics simulation about 13,000 times faster than the fastest known classical algorithm on the Frontier supercomputer. Specifically, the quantum computer took around two hours for a calculation that would have taken Frontier more than three years. This not only surpasses previous benchmarks but also brings the quantum computer closer to practical applications for the first time.

Previous demonstrations of "Quantum Supremacy"—such as in 2019 with the Sycamore chip—suffered from accusations of being detached from reality. At that time, the focus was on abstract tasks with no practical use, which were, in part, later surpassed by improved classical algorithms. Quantum Echoes, on the other hand, meets two crucial criteria: it addresses a physically relevant problem, and the results can be verified by other quantum computers or experimental methods, such as Nuclear Magnetic Resonance (NMR).

Journey into the Past

The functionality of the algorithm resembles a time-reversal experiment. First, a quantum system is developed in a specific direction, then deliberately disturbed—such as by specifically adjusting a qubit—and subsequently guided backward through the original operations.

By comparing forward and backward development, measurable interferences arise in the system. These "echoes" are extremely sensitive to the smallest changes in the system and provide precise information about the dynamics and structure within the model.

In the current study, Google used this method in collaboration with research teams from the USA, Canada, the United Kingdom, and Australia to analyze molecular structures within the scope of nuclear magnetic resonance (NMR). The algorithm served as a kind of "molecular ruler" to determine atomic distances with high precision.

Verifiable, Reproducible Results

In contrast to classical NMR, Quantum Echoes enabled a more accurate mapping of spin interactions over greater distances within a molecule—an effect that is either computationally intensive or no longer feasible to model classically. While the current experiments were still limited to small molecules with 15 to 28 atoms—still manageable for classical computers—the direction is clear: with improved hardware and error correction, significantly more complex structures could follow.

Another hallmark of success: the results are reproducible. Other research institutions with comparable quantum hardware could run the algorithm and validate the findings—a fundamental step toward scientific validation in quantum computing.

The researchers see Quantum Echoes not only as a useful tool for fundamental research but also for potential applications in drug development, catalyst research, or the development of new battery materials.

In the long term, the method could also be used in the field of quantum sensing. Google refers to this as the "Quantum Scope"—an instrument designed to make quantum information as usable as microscopes or telescopes make classical information.

Real Practical Applicability Within the Next Five Years?

Despite the successes, the challenge remains great. The complexity of molecules and quantum systems grows exponentially, and the current hardware—including Google's Willow—is far from achieving the necessary scaling for universal applications.

Google itself continues to pursue a clear roadmap: the next milestone is the construction of a fault-tolerant logical qubit. Only with such qubits can large, stable quantum computers for practical tasks become a reality.

"We believe that within the next five years, we will be able to solve real problems that are inaccessible to classical computers," said Hartmut Neven, Head of Google Quantum AI. An ambitious goal—but for the first time, it no longer feels purely theoretical.

(sg)

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