9 research outputs found
Hybrid quantum systems of atoms and ions
In recent years, ultracold atoms have emerged as an exceptionally
controllable experimental system to investigate fundamental physics, ranging
from quantum information science to simulations of condensed matter models.
Here we go one step further and explore how cold atoms can be combined with
other quantum systems to create new quantum hybrids with tailored properties.
Coupling atomic quantum many-body states to an independently controllable
single-particle gives access to a wealth of novel physics and to completely new
detection and manipulation techniques. We report on recent experiments in which
we have for the first time deterministically placed a single ion into an atomic
Bose Einstein condensate. A trapped ion, which currently constitutes the most
pristine single particle quantum system, can be observed and manipulated at the
single particle level. In this single-particle/many-body composite quantum
system we show sympathetic cooling of the ion and observe chemical reactions of
single particles in situ.Comment: ICAP proceeding
Cold heteronuclear atom-ion collisions
We study cold heteronuclear atom ion collisions by immersing a trapped single
ion into an ultracold atomic cloud. Using ultracold atoms as reaction targets,
our measurement is sensitive to elastic collisions with extremely small energy
transfer. The observed energy-dependent elastic atom-ion scattering rate
deviates significantly from the prediction of Langevin but is in full agreement
with the quantum mechanical cross section. Additionally, we characterize
inelastic collisions leading to chemical reactions at the single particle level
and measure the energy-dependent reaction rate constants. The reaction products
are identified by in-trap mass spectrometry, revealing the branching ratio
between radiative and non-radiative charge exchange processes
Laser spectroscopy and cooling of Yb+ ions on a deep-UV transition
We perform laser spectroscopy of Yb+ ions on the 4f14 6s 2S_{1/2} - 4f13 5d
6s 3D[3/2]_{1/2} transition at 297 nm. The frequency measurements for 170Yb+,
172Yb+, 174Yb+, and 176Yb+ reveal the specific mass shift as well as the field
shifts. In addition, we demonstrate laser cooling of Yb+ ions using this
transition and show that light at 297 nm can be used as the second step in the
photoionization of neutral Yb atoms
Kinetics of a single trapped ion in an ultracold buffer gas
The immersion of a single ion confined by a radiofrequency trap in an
ultracold atomic gas extends the concept of buffer gas cooling to a new
temperature regime. The steady state energy distribution of the ion is
determined by its kinetics in the radiofrequency field rather than the
temperature of the buffer gas. Moreover, the finite size of the ultracold gas
facilitates the observation of back-action of the ion onto the buffer gas. We
numerically investigate the system's properties depending on atom-ion mass
ratio, trap geometry, differential cross-section, and non-uniform neutral atom
density distribution. Experimental results are well reproduced by our model
considering only elastic collisions. We identify excess micromotion to set the
typical scale for the ion energy statistics and explore the applicability of
the mobility collision cross-section to the ultracold regime.Comment: 10 pages, 6 figure
A trapped single ion inside a Bose-Einstein condensate
Improved control of the motional and internal quantum states of ultracold
neutral atoms and ions has opened intriguing possibilities for quantum
simulation and quantum computation. Many-body effects have been explored with
hundreds of thousands of quantum-degenerate neutral atoms and coherent
light-matter interfaces have been built. Systems of single or a few trapped
ions have been used to demonstrate universal quantum computing algorithms and
to detect variations of fundamental constants in precision atomic clocks. Until
now, atomic quantum gases and single trapped ions have been treated separately
in experiments. Here we investigate whether they can be advantageously combined
into one hybrid system, by exploring the immersion of a single trapped ion into
a Bose-Einstein condensate of neutral atoms. We demonstrate independent control
over the two components within the hybrid system, study the fundamental
interaction processes and observe sympathetic cooling of the single ion by the
condensate. Our experiment calls for further research into the possibility of
using this technique for the continuous cooling of quantum computers. We also
anticipate that it will lead to explorations of entanglement in hybrid quantum
systems and to fundamental studies of the decoherence of a single, locally
controlled impurity particle coupled to a quantum environment