ABSTRACT
The thermal friction force acting on an atom moving relative to a thermal photon bath is known to be proportional to an integral over the imaginary part of the frequency-dependent atomic (dipole) polarizability. Using a numerical approach, we find that blackbody friction on atoms either in dilute environments or in hot ovens is larger than previously thought by orders of magnitude. This enhancement is due to far off-resonant driving of transitions by low-frequency thermal radiation. At typical temperatures, the blackbody radiation maximum lies far below the atomic transition wavelengths. Surprisingly, due to the finite lifetime of atomic levels, which gives rise to Lorentzian line profiles, far off-resonant excitation leads to the dominant contribution for blackbody friction.
ABSTRACT
We present first experimental evidence for quantum reflection, originating exclusively from an attractive potential between an atom and a solid surface, at energies far from the threshold E(i)-->0. The system of light and stable 3He atoms scattering from an alpha-quartz crystal allows confirmation of recent theory on quantum reflection up to its asymptotic behavior, determined by the nonretarded van der Waals potential -C(3)/r(3). From the data, the gas-solid interaction potential is deduced quantitatively, covering the energy region, in which retardation plays a role.
