160 research outputs found
Giant formation rates of ultracold molecules via Feshbach Optimized Photoassociation
Ultracold molecules offer a broad variety of applications, ranging from
metrology to quantum computing. However, forming "real" ultracold molecules,
{\it i.e.} in deeply bound levels, is a very difficult proposition. Here, we
show how photoassociation in the vicinity of a Feshbach resonance enhance
molecular formation rates by several orders of magnitude. We illustrate this
effect in heteronuclear systems, and find giant rate coefficients even in
deeply bound levels. We also give a simple analytical expression for the
photoassociation rates, and discuss future applications of the Feshbach
Optimized Photoassociation, or FOPA, technique
Feshbach-optimized photoassociation of ultracold LiRb molecules with short pulses
Two-color photoassociation of ground state LiRb molecules via the
electronic state using short pulses near a magnetic Feshbach
resonance is studied theoretically. A near-resonant magnetic field is applied
to mix the hyperfine singlet and triplet components of the initial wave
function and enhance the photoassociation rate, before the population is
transferred to the ground state by a second pulse. We show that an increase of
up to three orders of magnitude in the absolute number of molecules produced is
attainable for deeply bound vibrational levels. This technique can be
generalized to other molecules with accessible magnetic Feshbach resonances.Comment: 11 pages, 10 figures; submitted to Phys. Rev.
Phase gate and readout with an atom/molecule hybrid platform
We suggest a combined atomic/molecular system for quantum computation, which
takes advantage of highly developed techniques to control atoms and recent
experimental progress in manipulation of ultracold molecules. We show that two
atoms of different species in a given site, {\it e.g.}, in an optical lattice,
could be used for qubit encoding, initialization and readout, with one atom
carrying the qubit, the other enabling a gate. In particular, we describe how a
two-qubit phase gate can be realized by transferring a pair of atoms into the
ground rovibrational state of a polar molecule with a large dipole moment, and
allowing two molecules to interact via their dipole-dipole interaction. We also
discuss how the reverse process of coherently transferring a molecule into a
pair of atoms could be used as a readout tool for molecular quantum computers
Controllable binding of polar molecules and meta-stability of 1-D gases with attractive dipole forces
We explore one-dimensional (1-D) samples of ultracold polar molecules with
attractive dipole-dipole interactions and show the existence of a repulsive
barrier due to a strong quadrupole interaction between molecules. This barrier
can stabilize a gas of ultracold KRb molecules and even lead to long-range
wells supporting bound states between molecules. The properties of these wells
can be controlled by external electric fields, allowing the formation of long
polymer-like chains of KRb, and studies of quantum phase transitions by varying
the effective interaction between molecules. We discuss the generalization of
those results to other systems
Feshbach resonances in ultracold ^{6,7}Li + ^{23}Na atomic mixtures
We report a theoretical study of Feshbach resonances in Li + Na
and Li + Na mixtures at ultracold temperatures using new accurate
interaction potentials in a full quantum coupled-channel calculation. Feshbach
resonances for in the initial collisional open channel LiNa are found to agree with previous
measurements, leading to precise values of the singlet and triplet scattering
lengths for the LiNa pairs. We also predict additional Feshbach
resonances within experimentally attainable magnetic fields for other collision
channels.Comment: 4 pages, 3 figure
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