Nuclear polaritons: Mössbauer source and resonant absorber investigated using the coherent paths model

Abstract

Resonant nuclei of a Mössbauer absorber, interacting with the recoil free emitted radiation from a Mössbauer source, can re-emit it without recoil, leading to nuclear-resonant scattering. During the nuclear resonance scattering in the Mössbauer absorber, intermediate states which are combinations of nuclear excited states and electromagnetic radiation (gamma radiation) states are produced. These states are called nuclear polaritons. In this paper, a description of the nuclear polariton inside a Mössbauer absorber is presented by adapting the quantum model previously developed by Heitler, Harris and Hoy, called “the coherent paths model”. This model allows the calculation of all spatial and temporal properties of the nuclear excited states as well as the electromagnetic radiation present inside a resonant absorber. The thickness of the absorber is modeled using a parameter N. The nuclear polariton results then from the magnetic dipole interaction between the quantified electromagnetic radiation and the resonant nuclei of the absorber. It is an entangled state, composed by the excitation of the nuclei (exciton) and the electromagnetic field. The evolution of the nuclear exciton, both as a function of time and as a function of the position of the resonant nuclei in the absorber, is studied. This constitutes the nuclear part of the polariton. The field associated with the gamma radiation inside the absorber is studied also as a function of position in the absorber and as a function of time, which is the field part of the polariton. Using the purely quantum coherent paths model, we find out that the energy of the polariton inside the absorber oscillates between the nuclear excitation and the field of electromagnetic radiation. Nuclear polariton study is then a potential method for probing matter at the subatomic scale.