# Classical computer solves problem thought to require quantum computing An ordinary laptop managed to solve a problem previously believed to need quantum hardware. - **Source:** [Latest Science News -- ScienceDaily](https://brifing.si/source/0eef8637-6c5b-4e79-8f5b-6c9c6b36cf16) - **Published:** 2026-07-20 - **Topic:** [Data & AI](https://brifing.si/c/data-ai) - **Original article:** - **On Brifing:** https://brifing.si/s/1a7398c8-c2b7-4e3f-a806-675d5e776064 ## Classical solution to quantum problem Researchers at the Flatiron Institute used a conventional computer and tensor networks to solve a problem thought to require quantum computing. This approach offers an efficient method that can even run on personal laptops. It could mark a new era in quantum system simulations. ## The challenge of qubit simulation The team successfully modeled the behavior of hundreds of interacting qubits. Quantum entanglement made these systems extremely difficult to simulate on classical computers. Traditional methods failed as wave function sizes grew exponentially. ## Power of tensor networks Researchers compressed wave functions using tensor networks. These mathematical structures efficiently represent quantum system information. Tindall describes the method as 'a zip file for the wave function'. The ITensor software enabled calculations even on laptops. ## Three-dimensional modeling For the first time, researchers modeled 3D quantum dynamics using 3D tensor networks. Working with these complex mathematical objects posed significant software engineering challenges. The method opens new possibilities for predicting quantum material behavior. ## Old algorithm's new application The team adapted the 1980s-era belief propagation algorithm for quantum systems. This simpler approach proved more efficient than other methods. It allowed researchers to tackle major challenges like three-dimensional problems that were previously intractable. ## Future of classical and quantum computing This work redefines the boundaries between classical and quantum computing. It demonstrates how the two fields can complement each other. Classical simulations may play a crucial role in understanding quantum computer capabilities, creating new collaboration opportunities in science. ## Sources covering this story - https://www.sciencedaily.com/releases/2026/07/260719040000.htm — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._