The Quantum Monte Carlo Sign Problem: Structure, Complexity, and New Directions

The Monte Carlo sign problem remains a central obstruction to scalable simulation of interacting quantum many-body systems. By undermining reliable importance sampling in quantum Monte Carlo, the main practical framework for large-scale quantum simulation, it renders wide classes of physically relevant models computationally intractable; despite conceptual advances and model-specific breakthroughs, no general resolution is known and the boundary between tractable and intractable regimes is poorly understood. This IPAM workshop brings together researchers from physics, applied mathematics, quantum information and theoretical computer science to examine sign-problem mitigation critically: to clarify the structural principles behind sign-free formulations, identify new algorithmic and complexity-theoretic perspectives, and train early-career researchers entering the field through lectures, tutorials, focused discussions and problem-driven sessions. The programme includes a poster session; registration includes a remote-participation option.