TRANSFORMING SIGNS TO PHASE DISTRIBUTIONS IN QUANTUM SIMULATIONS

A method is developed which speeds up averaging in quantum simulations where minus signs cause difficulties. A Langevin equation method in c onjunction with a replication algorithm is used, enabling one to avera ge over a continuously varying complex number. Instead of ensemble ave raging this number directly, the phase of the complex number is follow ed over time. The method is illustrated in some simple cases where the answers obtained can be compared to exact results, and also compared to conventional averaging procedures which converge orders of magnitud e more slowly than this method. Limitations of this method are also de scribed.