In physics, EP quantum mechanics is a theory of motion of point particles, partly included in the framework of quantum trajectory representation theories of quantum mechanics, based upon an equivalence postulate similar in content to the equivalence principle of general relativity, rather than on the traditional Copenhagen interpretation of quantum mechanics. The equivalence postulate states that all one-particle systems can be connected by a non-degenerate coordinate transformation, more precisely by a map over the cotangent bundle of the position manifold, so that there exists a quantum action function
is the canonical one-form. This property is the heart of the EP formulation of quantum mechanics. An immediate consequence of the EP is the removal of the rest frame. The theory is based on symmetry properties of Schwarzian derivative and on the quantum stationary Hamilton-Jacobi equation (QSHJE), which is a partial differential equation for the quantum action function
with