On the Steady-state Probability Distribution of Nonequilibrium Stochastic Systems

A driven stochastic system in a constant temperature heat bath relaxes into a steady state that is characterized by the steady-state probability distribution. We investigate the relationship between the driving force and the steady-state probability distribution. We adopt the force decomposition method in which the force is decomposed as the sum of a gradient of a steady-state potential and the remaining part. The decomposition method allows one to find a set of force fields each of which is compatible with a given steady state. Such a knowledge provides useful insight into stochastic systems, especially those in a nonequilibrium situation. We demonstrate the decomposition method in stochastic systems under overdamped and underdamped dynamics and discuss the connection between them.