Fluctuations of the Casimir-Polder force between an atom and a conducting wall

Abstract

We consider quantum fluctuations of the Casimir-Polder force between a neutral atom and a perfectly conducting wall in the ground state of the system. In order to obtain the atom-wall force fluctuation we first define an operator directly associated with the force experienced by the atom considered as a polarizable body in an electromagnetic field and we use a time- averaged force operator in order to avoid ultraviolet divergences appearing in the fluctuation of the force. This time-averaged force operator takes into account that any measurement involves a finite time. We also calculate the Casimir-Polder force fluctuation for an atom between two conducting walls. Experimental observability of these Casimir-Polder force fluctuations is also discussed, as well as the dependence of the relative force fluctuation on the duration of the measurement.