A major 'cheat code' for quantum computers just hit the exact same brick wall that makes regular computers slow down.
arXiv · March 16, 2026 · 2603.13073
Why it matters
For years, a method called VQE was the biggest hope for using near-term quantum computers to solve complex chemistry. This study proves that the method's complexity grows exponentially as problems get bigger, potentially crushing the dream of using it for large-scale discovery.
From the abstract
The Variational Quantum Eigensolver (VQE) is widely regarded as a promising algorithm for calculating ground states of quantum systems that are intractable for classical computers. This promise is typically motivated by the hope of mitigating the exponential growth of Hilbert space with system size. Here we scrutinize how the computational cost of adaptive VQE scales with the size of the target system. We demonstrate that the Rényi entropy derived from classical simulations predicts the required