On the feasibility of radiation emission from a regular photon flux rigidly oriented in space

Yu. M. Golubev, D. F. Parsons

Jonas Schäfer, Benjamin A. Stickler, Klaus Hornberger

Levitated nanoparticles are a promising platform for sensing applications and for macroscopic quantum experiments. While the nanoparticles' motional temperatures can be reduced to near absolute zero, their uncontrolled internal degrees of freedom remain much hotter, inevitably leading to the emission of heat radiation. The decoherence and motional heating caused by this thermal emission process is still poorly understood beyond the case of the center-of-mass motion of point particles. Here, we present the master equation describing the impact of heat radiation on the motional quantum state of arbitrarily sized and shaped dielectric rigid rotors. It predicts the localization of spatio-orientational superpositions only based on the bulk material properties and the particle geometry. A counterintuitive and experimentally relevant implication of the presented theory is that orientational superpositions of optically isotropic bodies are not protected by their symmetry, even in the small-particle limit.

B.I. Bondarev

Adán S. Sánchez, P. Halevi

We study the spontaneous emission of an atom embedded in a one-dimensional photonic crystal or superlattice using a classical electrodynamic theory of radiation. The rate of emission is a function of the frequency of the emitted photon, the dipole's position and orientation, as well as the geometric and material parameters of the superlattice. The emission spectrum shows an oscillatory behavior which follows the photonic band structure. For TE modes, there are frequency regions where radiative emission is completely prohibited due to the absence of modes with k//>omega/c; the radiation is then TM polarized. In addition to the radiative modes, there are always evanescent modes with k//>omega/c which are waveguided by the dielectric layers. The evanescent contribution to the spontaneous emission is dominant if a dielectric layer is in the near field region of the dipole. For TM modes, emission rates greatly vary for parallel and perpendicular dipole moments. In a photonic crystal with a high filling fraction of the dielectric and perpendicular dipoles located in the low-index layer, the decay rate can be as much as 76 times the free space value for a single atom and 50 times for a gas of atoms. We also find that the rate of emission presents a strong dependence on the atom's position.

V. I. Matveev, Pulat K. Khabibullaev

Reinhold Fürth