Two-photon absorption in GdCl 3 (A)

Richard S. Meltzer, Hugh C. Wolfe, C. D. Graham +1 more

We report the observation of a magnon sideband in the 6P7/2 ⇐ 8S7/2 optical absorption spectrum of Gd+3 in the ferromagnetic insulator GdCl3. The transition energy and its dependence on magnetic field demonstrate this to arise from the simultaneous excitation of a magnon and optical exciton. The decrease in its intensity with increasing magnetic field suggest the source of its intensity is directly connected with the zero‐point spin deviations which occur in a ferromagnet possessing significant magnetic dipolar interactions. The magnitude of the intensity is shown to be consistent with a single‐ion transition mechanism which because of the zero‐point spin deviations allows a small probability for a double‐excitation process. This transition mechanism is distinct from that responsible for the previously observed magnon sidebands in the transition‐metal magnetic insulators.

B. Jacquier, Y. Salem, C. Linarès +3 more

Stephen V. Kershaw

Rachid Mahiou

Fluorescence de nagdf::(4), k::(2)gdf::(5), gdcl::(3). Excitation selective dans l'ultraviolet (excitation a 1 photon) ou dans le rouge (excitation a 2 photons) d'une des composantes stark du multiplet **(6)p::(7/2) de gd**(3+). Le declin de la fluorescence entre 4,4k et la temperature ambiante permet de determiner le mode de diffusion de l'energie d'excitation. Effet de la densite d'excitation. Mise en evidence d'une fluorescence anti-stokes issue des niveaux **(6)g::(7/2), **(6)d::(3/2) et **(6)i::(7/2). Effet d'un champ magnetique

Baihong Li, Holger Friedrich Hofmann

Two photon absorption processes are known to be sensitive to energy-time entanglement between the absorbed photons. It should therefore be possible to characterize the energy-time entanglement by observing the two photon absorption cross-sections in a known medium controlled by external conditions. In this paper, we analyze the correspondence between two photon absorption and projective measurements of the two photon wavefunction. It is shown that the two photon absorption process is described by a projection onto an energy-time entangled two photon state, indicating that the absorption cross-section can provide direct evidence of entanglement between the absorbed photon pairs.