1,275 research outputs found
Single atom detection in ultracold quantum gases: a review of current progress
The recent advances in single atom detection and manipulation in experiments
with ultracold quantum gases are reviewed. The discussion starts with the basic
principles of trapping, cooling and detecting single ions and atoms. The
realization of single atom detection in ultracold quantum gases is presented in
detail and the employed methods, which are based on light scattering, electron
scattering, field ionization and direct neutral particle detection are
discussed. The microscopic coherent manipulation of single atoms in a quantum
gas is also covered. Various examples are given in order to highlight the power
of these approaches to study many-body quantum systems
Scanning electron microscopy of cold gases
Ultracold quantum gases offer unique possibilities to study interacting
many-body quantum systems. Probing and manipulating such systems with ever
increasing degree of control requires novel experimental techniques. Scanning
electron microscopy is a high resolution technique which can be used for in
situ imaging, single site addressing in optical lattices and precision density
engineering. Here, we review recent advances and achievements obtained with
this technique and discuss future perspectives.Comment: Accepted for publication in Journal of Physics B: Atomic, Molecular
and Optical Physics as a Topical Revie
Dynamically Probing Ultracold Lattice Gases via Rydberg Molecules
We show that the excitation of long-range Rydberg molecules in a
three-dimensional optical lattice can be used as a position- and time-sensitive
probe of the site occupancy in the system. To this end, we detect the ions
which are continuously generated by the decay of the formed Rydberg molecules.
While a superfluid gas shows molecule formation for all parameters, a Mott
insulator with filling reveals a strong suppression of the number of
formed molecules. In the limit of weak probing, the technique can be used to
probe the superfluid to Mott-insulator transition in real-time. Our method can
be extended to higher fillings and has various applications for the real-time
diagnosis and manipulation of ultracold lattice gases.Comment: 6 pages, 5 figure
Experimental realization of a Rydberg optical Feshbach resonance in a quantum many-body system
Feshbach resonances in ultra-cold atomic gases have led to some of the most
important advances in atomic physics. They did not only enable ground breaking
work in the BEC-BCS crossover regime [1], but are also widely used for the
association of ultra-cold molecules [2], leading to the formation of molecular
Bose-Einstein condensates [3,4] and ultra-cold dipolar molecular systems [5].
Here, we demonstrate the experimental realization of an optical Feshbach
resonance using ultra-long range Rydberg molecules [6]. We show their practical
use by tuning the revival time of a quantum many-body system quenched into a
deep optical lattice. Our results open up many applications for Rydberg optical
Feshbach resonances as ultra-long range Rydberg molecules have a plenitude of
available resonances for nearly all atomic species. Among the most intriguing
prospects is the engineering of genuine three- and four-body interactions via
coupling to trimer and tetramer molecular states [7]
Coherent perfect absorber and laser for nonlinear waves in optical waveguide arrays
A localized non-Hermitian potential can operate as a coherent perfect
absorber or as a laser for nonlinear waves. The effect is illustrated for an
array of optical waveguides, with the central waveguide being either active or
absorbing. The arrays situated to the left and to the right from the center can
have different characteristics. The result is generalized to setups with the
central waveguide carrying additional nonlinear dissipation or gain and to the
two-dimensional arrays with embedded one-dimensional absorbing or lasing
sub-arrays.Comment: to appear in Optics Letter
Rydberg molecule-induced remote spin-flips
We have performed high resolution photoassociation spectroscopy of rubidium
ultra long-range Rydberg molecules in the vicinity of the 25 state. Due to
the hyperfine interaction in the ground state perturber atom, the emerging
mixed singlet-triplet potentials contain contributions from both hyperfine
states. We show that this can be used to induce remote spin-flips in the
perturber atom upon excitation of a Rydberg molecule. When furthermore the
spin-orbit splitting of the Rydberg state is comparable to the hyperfine
splitting in the ground state, the orbital angular momentum of the Rydberg
electron is entangled with the nuclear spin of the perturber atom. Our results
open new possibilities for the implementation of spin-dependent interactions
for ultracold atoms in bulk systems and in optical lattices.Comment: 6 pages, 3 figure
Non-equilibrium steady-states in a driven-dissipative superfluid
We experimentally study a driven-dissipative Josephson junction array,
realized with a weakly interacting Bose Einstein condensate residing in a
one-dimensional optical lattice. Engineered losses on one site act as a local
dissipative process, while tunneling from the neighboring sites constitutes the
driving force. We characterize the emerging steady-states of this atomtronic
device. With increasing dissipation strength the system crosses from a
superfluid state, characterized by a coherent Josephson current into the lossy
site to a resistive state, characterized by an incoherent hopping transport.
For intermediate values of , the system exhibits bistability, where a
superfluid and a resistive branch coexist. We also study the relaxation
dynamics towards the steady-state, where we find a critical slowing down,
indicating the presence of a non-equilibrium phase transition
A high repetition deterministic single ion source
We report on a deterministic single ion source with high repetition rate and
high fidelity. The source employs a magneto-optical trap, where ultracold
Rubidium atoms are photoionized. The electrons herald the creation of a
corresponding ion, whose timing information is used to manipulate its
trajectory in flight. We demonstrate an ion rate of up to 40 kHz and achieve a
fidelity for single ion operation of 98 %. The technique can be used for all
atomic species, which can be laser-cooled, and opens up new applications in ion
microscopy, ion implantation and surface spectroscopy
An ultracold heavy Rydberg system formed from ultra-long-range molecules bound in a stairwell potential
We propose a scheme to realize a heavy Rydberg system (HRS), a bound pair of
oppositely charged ions, from a gas of ultracold atoms. The intermediate step
to achieve large internuclear separations is the creation of a unique class of
ultra-long-range Rydberg molecules bound in a stairwell potential energy curve.
Here, a ground-state atom is bound to a Rydberg atom in an oscillatory
potential emerging due to attractive singlet -wave electron scattering. The
utility of our approach originates in the large electronic dipole transition
element between the Rydberg- and the ionic molecule, while the nuclear
configuration of the ultracold gas is preserved. The Rabi coupling between the
Rydberg molecule and the heavy Rydberg system is typically in the MHz range and
the permanent electric dipole moments of the HRS can be as large as one
kilo-Debye. We identify specific transitions which place the creation of the
heavy Rydberg system within immediate reach of experimental realization.Comment: 14 pages, 5 figure
High Resolution Imaging of Single Atoms in a Quantum Gas
Our knowledge on ultracold quantum gases is strongly influenced by our
ability to probe these objects. In situ imaging combined with single atom
sensitivity is an especially appealing scenario as it can provide direct
information on the structure and the correlations of such systems. For a
precise characterization a high spatial resolution is mandatory. In particular,
the perspective to study quantum gases in optical lattices makes a resolution
well below one micrometer highly desirable. Here, we report on a novel
microscopy technique which is based on scanning electron microscopy and allows
for the detection of single atoms inside a quantum gas with a spatial
resolution of better than 150 nm. Imaging a Bose-Einstein condensate in a
one-dimensional optical lattice with 600 nm period we demonstrate single site
addressability in a sub-um optical lattice. The technique offers exciting
possibilities for the preparation, manipulation and analysis of quantum gases.Comment: 5 pages, 5 figure
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