88 research outputs found
Sympathetic Wigner function tomography of a dark trapped ion
A protocol is provided to reconstruct the Wigner function for the motional
state of a trapped ion via fluorescence detection on another ion in the same
trap. This "sympathetic tomography" of a dark ion without optical transitions
suitable for state measurements is based on the mapping of its motional state
onto one of the collective modes of the ion pair. The quantum state of this
vibrational eigenmode is subsequently measured through sideband excitation of
the bright ion. Physical processes to implement the desired state transfer and
read-out are derived, and the accomplishment of the scheme for different mass
ratios is evaluated.Comment: 8 pages, 5 figure
Formation of ultracold LiCs molecules
We present the first observation of ultracold LiCs molecules. The molecules
are formed in a two-species magneto-optical trap and detected by two-photon
ionization and time-of-flight mass spectrometry. The production rate
coefficient is found to be in the range 10^{-18}\unit{cm^3s^{-1}} to
10^{-16}\unit{cm^3s^{-1}}, at least an order of magnitude smaller than for
other heteronuclear diatomic molecules directly formed in a magneto-optical
trap.Comment: 8 pages, 2 figure
Atom-molecule collisions in an optically trapped gas
Cold inelastic collisions between confined cesium (Cs) atoms and Cs
molecules are investigated inside a CO laser dipole trap. Inelastic
atom-molecule collisions can be observed and measured with a rate coefficient
of cm s, mainly independent of the
molecular ro-vibrational state populated. Lifetimes of purely atomic and
molecular samples are essentially limited by rest gas collisions. The pure
molecular trap lifetime ranges 0,3-1 s, four times smaller than the atomic one,
as is also observed in a pure magnetic trap. We give an estimation of the
inelastic molecule-molecule collision rate to be cm
s
Geometric quantum gate for trapped ions based on optical dipole forces induced by Gaussian laser beams
We present an implementation of quantum logic gates via internal state
dependent displacements of ions in a linear Paul trap caused by optical dipole
forces. Based on a general quantum analysis of the system dynamics we consider
specific implementations with alkaline earth ions. For experimentally realistic
parameters gate infidelities as low as can be obtained.Comment: 10 pages, 4 figure
Population redistribution in optically trapped polar molecules
We investigate the rovibrational population redistribution of polar molecules
in the electronic ground state induced by spontaneous emission and blackbody
radiation. As a model system we use optically trapped LiCs molecules formed by
photoassociation in an ultracold two-species gas. The population dynamics of
vibrational and rotational states is modeled using an ab-initio electric dipole
moment function and experimental potential energy curves. Comparison with the
evolution of the v"=3 electronic ground state yields good qualitative
agreement. The analysis provides important input to assess applications of
ultracold LiCs molecules in quantum simulation and ultracold chemistry.Comment: 6 pages, 5 figures, EPJD Topical issue on Cold Quantum Matter -
Achievements and Prospect
Experimental investigation of ultracold atom-molecule collisions
Ultracold collisions between Cs atoms and Cs2 dimers in the electronic ground
state are observed in an optically trapped gas of atoms and molecules. The Cs2
molecules are formed in the triplet ground state by cw-photoassociation through
the outer well of the 0g-(P3/2) excited electronic state. Inelastic
atom-molecule collisions converting internal excitation into kinetic energy
lead to a loss of Cs2 molecules from the dipole trap. Rate coefficients are
determined for collisions involving Cs atoms in either the F=3 or F=4 hyperfine
ground state and Cs2 molecules in either highly vibrationally excited states
(v'=32-47) or in low vibrational states (v'=4-6) of the a ^3 Sigma_u^+ triplet
ground state. The rate coefficients beta ~10^{-10} cm^3/s are found to be
largely independent of the vibrational and rotational excitation indicating
unitary limited cross sections.Comment: 4 pages, 3 figures, submitted for publicatio
Non-Destructive Identification of Cold and Extremely Localized Single Molecular Ions
A simple and non-destructive method for identification of a single molecular
ion sympathetically cooled by a single laser cooled atomic ion in a linear Paul
trap is demonstrated. The technique is based on a precise determination of the
molecular ion mass through a measurement of the eigenfrequency of a common
motional mode of the two ions. The demonstrated mass resolution is sufficiently
high that a particular molecular ion species can be distinguished from other
equally charged atomic or molecular ions having the same total number of
nucleons
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