250 research outputs found
Laser Spinning of Nanotubes: A path to fast-rotating microdevices
We show that circularly polarized light can spin nanotubes with GHz
frequencies. In this method, angular moments of infrared photons are resonantly
transferred to nanotube phonons and passed to the tube body by "umklapp"
scattering. We investigate experimental realization of this ultrafast rotation
in carbon nanotubes, levitating in an optical trap and undergoing mechanical
vibrations, and discuss possible applications to rotating microdevices.Comment: 4 pages, 3 Postscript figure
On the treatment of -changing proton-hydrogen Rydberg atom collisions
Energy-conserving, angular momentum-changing collisions between protons and
highly excited Rydberg hydrogen atoms are important for precise understanding
of atomic recombination at the photon decoupling era, and the elemental
abundance after primordial nucleosynthesis. Early approaches to -changing
collisions used perturbation theory for only dipole-allowed () transitions. An exact non-perturbative quantum mechanical treatment is
possible, but it comes at computational cost for highly excited Rydberg states.
In this note we show how to obtain a semi-classical limit that is accurate and
simple, and develop further physical insights afforded by the non-perturbative
quantum mechanical treatment
Potential energy curves for the interaction of Ag(5s) and Ag(5p) with noble gas atoms
We investigate the interaction of ground and excited states of a silver atom
with noble gases (NG), including helium. Born-Oppenheimer potential energy
curves are calculated with quantum chemistry methods and spin-orbit effects in
the excited states are included by assuming a spin-orbit splitting independent
of the internuclear distance. We compare our results with experimentally
available spectroscopic data, as well as with previous calculations. Because of
strong spin-orbit interactions, excited Ag-NG potential energy curves cannot be
fitted to Morse-like potentials. We find that the labeling of the observed
vibrational levels has to be shifted by one unit
Ultracold giant polyatomic Rydberg molecules: coherent control of molecular orientation
We predict the existence of a class of ultracold giant molecules formed from
trapped ultracold Rydberg atoms and polar molecules. The interaction which
leads to the formation of such molecules is the anisotropic charge-dipole
interaction (). We show that prominent candidate molecules such as KRb
and deuterated hydroxyl (OD) should bind to Rydberg rubidium atoms, with
energies GHz at distances m. These
molecules form in double wells, mimicking chiral molecules, with each well
containing a particular dipole orientation. We prepare a set of correlated
dressed electron-dipole eigenstates which are used in a resonant Raman scheme
to coherently control the dipole orientation and to create cat-like entangled
states of the polar molecule.Comment: 4 pages, 4 figure
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