The Physics Society of Iran Iranian Journal of Physics Research 1682-6957 Articles in Press 2026 01 20 Effect of external field on the spatial correlations of two trapped micro-spheres, in the presence of a wall Effect of external field on the spatial correlations of two trapped micro-spheres, in the presence of a wall 3728 FA Setareh Dabbaghchian Department of Physics, University of Guilan, P.O. Box 41335-1914, Rasht, Iran Golnaz Najafi Golvandani Department of Physics, University of Guilan, P.O. Box 41335-1914, Rasht, Iran Seyyed Nader Rasuli Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom 0000-0002-8238-2182 Journal Article 2025 10 16 One simple combination of particles which captures effect of hydrodynamics interactions consists of two trapped ‎beads, immersed in fluid, each with a single degree of freedom, and fluctuating around their equilibrium ‎positions. Given such a system in the presence of a flat boundary, we consider effect of an external electrical or ‎temperature field on it. The external field push the two beads system, out of equilibrium. We calculate beads’ ‎auto/cross correlations in the presence of external field, then investigate if these auto/cross correlations can be ‎used to reveal the presence of a possible external field, and its nature. We find that the former question could be ‎answered successfully, while the latter requires more information or degrees of freedom for beads and the ‎observer. ‎ One simple combination of particles which captures effect of hydrodynamics interactions consists of two trapped ‎beads, immersed in fluid, each with a single degree of freedom, and fluctuating around their equilibrium ‎positions. Given such a system in the presence of a flat boundary, we consider effect of an external electrical or ‎temperature field on it. The external field push the two beads system, out of equilibrium. We calculate beads’ ‎auto/cross correlations in the presence of external field, then investigate if these auto/cross correlations can be ‎used to reveal the presence of a possible external field, and its nature. We find that the former question could be ‎answered successfully, while the latter requires more information or degrees of freedom for beads and the ‎observer. ‎ https://ijpr.iut.ac.ir/article_3728_460b491b917d4185ed1f5be97229721a.pdf