78 research outputs found
Yang-Yang thermodynamics on an atom chip
We investigate the behavior of a weakly interacting nearly one-dimensional
(1D) trapped Bose gas at finite temperature. We perform in situ measurements of
spatial density profiles and show that they are very well described by a model
based on exact solutions obtained using the Yang-Yang thermodynamic formalism,
in a regime where other, approximate theoretical approaches fail. We use
Bose-gas focusing [Shvarchuck etal., Phys. Rev. Lett. 89, 270404 (2002)] to
probe the axial momentum distribution of the gas, and find good agreement with
the in situ results.Comment: extended introduction and conclusions, and minor changes throughout;
accepted for publication in Phys. Rev. Let
Characterizing the local vectorial electric field near an atom chip using Rydberg state spectroscopy
We use the sensitive response to electric fields of Rydberg atoms to
characterize all three vector components of the local electric field close to
an atom-chip surface. We measured Stark-Zeeman maps of and Rydberg
states using an elongated cloud of ultracold Rubidium atoms ( K)
trapped magnetically m from the chip surface. The spectroscopy of
states yields a calibration for the generated local electric field at the
position of the atoms. The values for different components of the field are
extracted from the more complex response of states to the combined electric
and magnetic fields. From the analysis we find residual fields in the two
uncompensated directions of V/cm and V/cm
respectively. This method also allows us to extract a value for the relevant
field gradient along the long axis of the cloud. The manipulation of electric
fields and the magnetic trapping are both done using on-chip wires, making this
setup a promising candidate to observe Rydberg-mediated interactions on a chip.Comment: 8 pages, 5 figure
Three-dimensional character of atom-chip-based rf-dressed potentials
We experimentally investigate the properties of radio-frequency-dressed
potentials for Bose-Einstein condensates on atom chips. The three-dimensional
potential forms a connected pair of parallel waveguides. We show that
rf-dressed potentials are robust against the effect of small magnetic-field
variations on the trap potential. Long-lived dipole oscillations of condensates
induced in the rf-dressed potentials can be tuned to a remarkably low damping
rate. We study a beam-splitter for Bose-Einstein condensates and show that a
propagating condensate can be dynamically split in two vertically separated
parts and guided along two paths. The effect of gravity on the potential can be
tuned and compensated for using a rf-field gradient.Comment: 9 pages, 7 figure
Controlling Stray Electric Fields on an Atom Chip for Rydberg Experiments
Experiments handling Rydberg atoms near surfaces must necessarily deal with
the high sensitivity of Rydberg atoms to (stray) electric fields that typically
emanate from adsorbates on the surface. We demonstrate a method to modify and
reduce the stray electric field by changing the adsorbates distribution. We use
one of the Rydberg excitation lasers to locally affect the adsorbed dipole
distribution. By adjusting the averaged exposure time we change the strength
(with the minimal value less than at
from the chip) and even the sign of the perpendicular field component. This
technique is a useful tool for experiments handling Ryberg atoms near surfaces,
including atom chips
Yang-Yang thermodynamics on an atom chip
We investigate the behavior of a weakly interacting nearly one-dimensional
(1D) trapped Bose gas at finite temperature. We perform in situ measurements of
spatial density profiles and show that they are very well described by a model
based on exact solutions obtained using the Yang-Yang thermodynamic formalism,
in a regime where other, approximate theoretical approaches fail. We use
Bose-gas focusing [Shvarchuck etal., Phys. Rev. Lett. 89, 270404 (2002)] to
probe the axial momentum distribution of the gas, and find good agreement with
the in situ results.Comment: extended introduction and conclusions, and minor changes throughout;
accepted for publication in Phys. Rev. Let
Yang-Yang thermometry and momentum distribution of a trapped one-dimensional Bose gas
We describe the use of the exact Yang-Yang solutions for the one-dimensional
Bose gas to enable accurate kinetic-energy thermometry based on the
root-mean-square width of an experimentally measured momentum distribution.
Furthermore, we use the stochastic projected Gross-Pitaevskii theory to provide
the first quantitative description of the full momentum distribution
measurements of Van Amerongen et al., Phys. Rev. Lett. 100, 090402 (2008). We
find the fitted temperatures from the stochastic projected Gross-Pitaevskii
approach are in excellent agreement with those determined by Yang-Yang
kinetic-energy thermometry.Comment: 5 pages, 3 figures. v2: Updated to published versio
Box traps on an atom chip for one-dimensional quantum gases
We present the implementation of tailored trapping potentials for ultracold
gases on an atom chip. We realize highly elongated traps with box-like
confinement along the long, axial direction combined with conventional harmonic
confinement along the two radial directions. The design, fabrication and
characterization of the atom chip and the box traps is described. We load
ultracold (K) clouds of Rb in a box trap, and demonstrate
Bose-gas focusing as a means to characterize these atomic clouds in arbitrarily
shaped potentials. Our results show that box-like axial potentials on atom
chips are very promising for studies of one-dimensional quantum gases.Comment: 9 pages 4 figure
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