6 research outputs found
Heat transfer between anisotropic nanopartricles: Enhancement and switching
We theoretically study heat transfer between two anisotropic nanoparticles in
vacuum, and derive closed expressions in terms of the anisotropic dipole
polarizabilities. We show that transfer between two small spheroids can be many
times as large as the one for two spheres of same volumes. Such increase with
anisotropy is also found for the heat emission of an isolated small spheroid.
Furthermore, we observe a strong dependence of transfer on the relative
orientation, yielding the interpretation as a heat transfer switch. The switch
quality, given as the ratio of transfer in the ``on'' and ``off'' positions, is
observed to be as large as in the near field and even larger in the far
field
Enhanced resonant force between two entangled identical atoms in a photonic crystal
We consider the resonant interaction energy and force between two identical
atoms, one in an excited state and the other in the ground state, placed inside
a photonic crystal. The atoms, having the same orientation of their dipole
moment, are supposed prepared in their symmetrical state and interact with the
quantum electromagnetic field. We consider two specific models of photonic
crystals: a one-dimensional model and an isotropic model. We show that in both
cases the resonant interatomic force can be strongly enhanced by the presence
of the photonic crystal, as a consequence of the modified dispersion relation
and density of states, in particular if the transition frequency of the atoms
is close to the edge of a photonic gap. Differences between the two models
considered of photonic crystal are discussed in detail, as well as comparison
with the analogous system of two impurity atoms in a quantum semiconductor
wire. A numerical estimate of the effect in a realistic situation is also
discussed.Comment: 8 page
Many-body heat radiation and heat transfer in the presence of a nonabsorbing background medium
Heat radiation and near-field radiative heat transfer can be strongly manipulated by adjusting geometrical shapes, optical properties, or the relative positions of the objects involved. Typically, these objects are considered as embedded in vacuum. By applying the methods of fluctuational electrodynamics, we derive general closed-form expressions for heat radiation and heat transfer in a system of N arbitrary objects embedded in a passive nonabsorbing background medium. Taking into account the principle of reciprocity, we explicitly prove the symmetry and positivity of transfer in any such system. Regarding applications, we find that the heat radiation of a sphere as well as the heat transfer between two parallel plates is strongly enhanced by the presence of a background medium. Regarding near- and far-field transfer through a gas like air, we show that a microscopic model (based on gas particles) and a macroscopic model (using a dielectric contrast) yield identical results. We also compare the radiative transfer through a medium like air and the energy transfer found from kinetic gas theory
Heat transfer between anisotropic nanopartricles: Enhancement and switching
International audienceWe theoretically study heat transfer between two anisotropic nanoparticles in vacuum, and derive closed expressions in terms of the anisotropic dipole polarizabilities. We show that transfer between two small spheroids can be many times as large as the one for two spheres of same volumes. Such increase with anisotropy is also found for the heat emission of an isolated small spheroid. Furthermore, we observe a strong dependence of transfer on the relative orientation, yielding the interpretation as a heat transfer switch. The switch quality, given as the ratio of transfer in the ''on'' and ''off'' positions, is observed to be as large as in the near field and even larger in the far field