Behavior of a Free Quantum Particle in the Poincaré Upper Half-Plane Geometry

Abstract: Inspired by the recent work of Filho et al., a Hermitian momentum operator is introduced in a general curved space with diagonal metric. The modified Hamiltonian associated with this new momentum is calculated and discussed. Furthermore, granting the validity of the Heisenberg equation in a curved space, the Ehrenfest theorem is generalized and interpreted with the new position-dependent differential operator in a curved space. The modified Hamiltonian leads to a modified time-independent Schr\"odinger equation, which is solved explicitly for a free particle in the Poincar\'e upper half-plane geometry. It is shown that a "free particle" does not behave as it is totally free due to curved background geometry.