Realizing Colloidal Artificial Ice on Arrays of Optical Traps
  We demonstrate how a colloidal version of artificial ice can be realized on optical trap lattices. Using numerical simulations, we show that this system obeys the ice rules and that for strong colloid-colloid interactions, an ordered ground state appears. We show that the ice rule ordering can occur for systems with as few as twenty-four traps and that the ordering transition can be observed at constant temperature by varying the barrier strength of the traps. 
A. Libal, C. Reichhardt, and C.J. Olson Reichhardt