This breakthrough represents a significant step in making quantum computers less error-prone as they scale up, overcoming a decades-long challenge.

Quantum computers are inherently "noisy," meaning that without error-correction technologies, one in every 1,000 qubits — the fundamental building blocks of a quantum computer — fails.

This high error rate has been a significant barrier to scaling up quantum machines. Conventional computers experience failures in only one in 1 billion billion bits.

Google's new quantum processing unit (QPU), dubbed "Willow," is the first in the world to achieve results that are "below threshold," a milestone described by computer scientist Peter Shor in 1995.

This means that errors in a quantum computer will reduce exponentially as more physical qubits are added. The team detailed their technology in a study published on December 9 in Nature.

Google Quantum AI's director of quantum hardware Julian Kelly said: "What we've been able to do in quantum error correction is a significant milestone — for the scientific community and the future of quantum computing — which is [to] show that we can make a system that operates below the quantum error correction threshold."

The "Willow" processor has 105 physical qubits and enhanced error-correction technologies, allowing for exponential error reduction.

The team improved calibration protocols, machine learning techniques to identify errors, device fabrication methods, and coherence times while retaining the ability to tune physical qubits for optimal performance.

The Google researchers tested Willow against the random circuit sampling (RCS) benchmark, a standard metric for assessing quantum computing chips. Willow performed a computation in under five minutes that would have taken today's fastest supercomputers 10 septillion years, a period close to a quadrillion times longer than the universe's age.

This achievement follows Google's previous milestone in 2019, when their Sycamore quantum computer passed the RCS benchmark by resolving a problem that would have taken a classical supercomputer 10,000 years to solve. The first edition of the Willow QPU also boasts a coherence time of nearly 100 microseconds, five times better than Sycamore's performance.

Google scientists are now focusing on demonstrating practical computations for today's quantum chips. They aim to create a "very, very good logical qubit" with an error rate of one in 1 million, requiring 1,457 physical qubits to be stitched together.