A Laptop Just Cracked the Problem D-Wave Said Only Quantum Computers Could Solve

A Laptop Takes On a Quantum Supercomputer

A team of physicists has delivered a striking blow to one of the most high-profile claims in quantum computing. Researchers at the Center for Computational Quantum Physics at the Simons Foundation's Flatiron Institute, working with collaborators at Boston University, have demonstrated that a classical computer can simulate a complex quantum dynamics problem that D-Wave Quantum claimed was beyond the reach of any conventional machine. In some cases, the work was carried out on nothing more exotic than a personal laptop.

The study, published in Science on 21 May 2026, directly challenges D-Wave's March 2025 paper, which used the company's 5,000-qubit Advantage2 annealing processor to simulate quantum dynamics in programmable spin glasses. D-Wave had estimated that the same task would take nearly a million years on the Frontier supercomputer at Oak Ridge National Laboratory and consume more electricity than the world produces in a year. CEO Alan Baratz called it "the world's first and only demonstration of quantum computational supremacy on a useful problem".

How the Classical Approach Works

The Flatiron team's secret weapon is a technique called a tensor network. Joseph Tindall, a researcher at the institute, described it as "a zip file for the wave function" — a way of compressing the enormous amount of information describing a quantum system into a compact, interconnected set of small numerical tables. By adapting a mathematical algorithm dating back to the 1980s and pairing it with a three-dimensional tensor network architecture and belief propagation, the researchers could track how these quantum systems evolve over time.

Many of the initial calculations were run on a laptop using ITensor, a high-performance software library developed at the centre. The simulations converged on solutions that matched theoretical predictions and agreed with the results reported by the quantum computing team — but without any quantum hardware at all.

A Pattern of Challenge and Response

This is not the first time D-Wave's claim has been questioned. Shortly after the original paper appeared, another group found a way for a classical supercomputer to solve a subset of the same problem in just over two hours. The new work goes considerably further, tackling the full benchmark and running it on modest, widely available hardware.

What It Means for Quantum Computing

Importantly, the researchers are not declaring quantum computers useless. Instead, the finding narrows the boundary of where genuine quantum advantage begins. It is the latest chapter in a long-running tug-of-war: every time quantum researchers claim a speedup, classical researchers sharpen their algorithms and raise the bar. The new methodology also opens fresh avenues for studying quantum dynamics and optimisation problems, suggesting that the back-and-forth is ultimately pushing both fields forward.