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By adapting an algorithm from the 1980s to the modern context of mathematical objects called tensor networks, researchers at the Flatiron Institute show that classical computers can tackle a class of problems previously claimed to be solvable only by quantum computers.

Using a conventional computer and cutting-edge mathematical tools and code, physicists at the Center for Computational Quantum Physics (CCQ) at the Simons Foundation’s Flatiron Institute and collaborators at Boston University have cracked a daunting quantum physics problem previously claimed to be solvable only by quantum computers.

The technique is so groundbreaking in its efficiency that the researchers were even able to use a personal laptop to solve the problem. By enabling scientists to squeeze extra problem-solving power from classical computers, the breakthrough methodology is opening new avenues for research on quantum dynamics and may be useful as a protocol for solving problems about finding the optimal solution amid an abundance of feasible ones.

The researchers report their work May 21 in Science .

The problem at hand involves simulating a quantum system composed of hundreds of interacting ‘qubits’ — the quantum computing equivalent of the bits used in classical computers — arranged in square, cubic or diamond lattices. While bits can have values of 0 or 1, qubits can exist in a superposition of multiple values, making it challenging for traditional computers to simulate their dynamics.

In a March 2025 article, also published in Science , a group of quantum computing researchers reported that they’d calculated the dynamics of a particularly intricate system of qubits using a quantum computer. They further claimed that their feat was impossible for classical computers to match.