Explore a conference presentation from TQC 2024 that investigates the classical simulation of noisy Instantaneous Quantum Polynomial (IQP) circuits. Learn how dephasing or depolarizing noise in IQP circuits can lead to efficient classical sampling after a critical constant depth, without requiring specific circuit architecture or anti-concentration assumptions. Discover why quantum supremacy experiments using IQP circuits might be more vulnerable to classical simulation than previously believed, due to how diagonal gates allow noise to accumulate predictably and break down entanglement. Delivered at the 19th Conference on the Theory of Quantum Computation, Communication and Cryptography at OIST, Japan, this 24-minute talk presents groundbreaking research that challenges existing assumptions about the classical intractability of IQP computations, with significant implications for quantum device testing and validation.