Phase precision of Mach–Zehnder interferometer in PM2.5 air pollution

This paper theoretically explores the effect of PM2.5 air pollution on the phase precision of a Mach-Zehnder inter- ferometer. With the increasing of PM2.5 concentration, phase precision for inputs of coherent state ＆ vacuum state and inputs of coherent state ＆ squeezed vacuum state will gradually decrease and be lower than the standard quantum limit. When the value of relative humidity is increasing, the precision of two input cases is decreasing much faster. We also find that the precision for inputs of coherent state ＆ squeezed state is better than that of coherent state ＆ vacuum state when PM2.5 concentration is lower. As PM2.5 concentration increases, the precision for inputs of coherent state ＆ squeezed state decreases faster, and then the two precisions tend to be the same while the concentration is higher.