1,029 research outputs found
Manipulation of Single Neutral Atoms in Optical Lattices
We analyze a scheme to manipulate quantum states of neutral atoms at
individual sites of optical lattices using focused laser beams. Spatial
distributions of focused laser intensities induce position-dependent energy
shifts of hyperfine states, which, combined with microwave radiation, allow
selective manipulation of quantum states of individual target atoms. We show
that various errors in the manipulation process are suppressed below
with properly chosen microwave pulse sequences and laser parameters. A similar
idea is also applied to measure quantum states of single atoms in optical
lattices.Comment: 5 pages, 3 figure
Interactions Between Rydberg-Dressed Atoms
We examine interactions between atoms continuously and coherently driven
between the ground state and a Rydberg state, producing "Rydberg-dressed
atoms." Because of the large dipolar coupling between two Rydberg atoms, a
small admixture of Rydberg character into a ground state can produce an atom
with a dipole moment of a few Debye, the appropriate size to observe
interesting dipolar physics effects in cold atom systems. We have calculated
the interaction energies for atoms that interact via the dipole-dipole
interaction and find that due to blockade effects, the R-dependent two-atom
interaction terms are limited in size, and can be R-independent up until the
dipolar energy is equal to the detuning. This produces R-dependent interactions
different from the expected 1/R^3 dipolar form, which have no direct analogy in
condensed matter physics, and could lead to new quantum phases in trapped
Rydberg systems.Comment: 5 pages, 7 figures; Accepted to Phys. Rev. A, 18 Aug. 201
Deeply subrecoil two-dimensional Raman cooling
We report the implementation of a two-dimensional Raman cooling scheme using
sequential excitations along the orthogonal axes. Using square pulses, we have
cooled a cloud of ultracold Cesium atoms down to an RMS velocity spread of
0.39(5) recoil velocity, corresponding to an effective temperature of 30 nK
(0.15 T_rec). This technique can be useful to improve cold atom atomic clocks,
and is particularly relevant for clocks in microgravity.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
Electron Temperature of Ultracold Plasmas
We study the evolution of ultracold plasmas by measuring the electron
temperature. Shortly after plasma formation, competition between heating and
cooling mechanisms drives the electron temperature to a value within a narrow
range regardless of the initial energy imparted to the electrons. In agreement
with theory predictions, plasmas exhibit values of the Coulomb coupling
parameter less than 1.Comment: 4 pages, plus four figure
Strongly inhibited transport of a 1D Bose gas in a lattice
We report the observation of strongly damped dipole oscillations of a quantum
degenerate 1D atomic Bose gas in a combined harmonic and optical lattice
potential. Damping is significant for very shallow axial lattices (0.25 photon
recoil energies), and increases dramatically with increasing lattice depth,
such that the gas becomes nearly immobile for times an order of magnitude
longer than the single-particle tunneling time. Surprisingly, we see no
broadening of the atomic quasimomentum distribution after damped motion. Recent
theoretical work suggests that quantum fluctuations can strongly damp dipole
oscillations of 1D atomic Bose gas, providing a possible explanation for our
observations.Comment: 5 pages, 4 figure
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