Measurement of persistence in 1D diffusion
  Using a novel NMR scheme we observed persistence in 1-D gas diffusion. Analytical approximations and numerical simulations have indicated that for an initially random array of spins undergoing diffusion, the probability p(t) that the average spin magnetization in a given region has not changed sign (i.e., ``persists'') up to time t follows a power law t^{-\theta}, where \theta\ depends on the dimensionality of the system. Using laser-polarized ^{129}Xe gas, we prepared an initial ``quasirandom'' 1D array of spin magnetization and then monitored the ensemble's evolution due to diffusion using real-time NMR imaging. Our measurements are consistent with analytical and numerical predictions of \theta \approx 0.12. 
Glenn P. Wong (1), Ross W. Mair (1), Ronald L. Walsworth (1), David G.   Cory (2) ((1) Harvard-Smithsonian Center for Astrop...