21 research outputs found
Life and death of a cold BaRb<sup>+</sup> molecule inside an ultracold cloud of Rb atoms
We study the evolution of a cold single BaRb+ molecule while it continuously collides with ultracold Rb atoms. The initially weakly bound molecule can undergo a sequence of elastic, inelastic, reactive, and radiative processes. We investigate these processes by developing methods for discriminating between different ion species, electronic states, and kinetic ion energy ranges. By analyzing the experimental data while taking into account theoretical insights, we obtain a consistent description of the typical trajectory through the manifold of available atomic and molecular states. Monte Carlo simulations describe the measured dynamics well. As a further result, we determine rates for collisional and radiative relaxation as well as photodissociation, spin-flip collisions, and chemical reactions
Coherent Manipulation of a Ca Spin Qubit in a Micro Ion Trap
We demonstrate the implementation of a spin qubit with a single Ca ion in a
micro ion trap. The qubit is encoded in the Zeeman ground state levels mJ=+1/2
and mJ=-1/2 of the S1/2 state of the ion. We show sideband cooling close to the
vibrational ground state and demonstrate the initialization and readout of the
qubit levels with 99.5% efficiency. We employ a Raman transition close to the
S1/2 - P1/2 resonance for coherent manipulation of the qubit. We observe single
qubit rotations with 96% fidelity and gate times below 5mus. Rabi oscillations
on the blue motional sideband are used to extract the phonon number
distribution. The dynamics of this distribution is analyzed to deduce the
trap-induced heating rate of 0.3(1) phonons/ms
Refining Mobile UML State Machines
We study the semantics and refinement of mobile objects, considering an extension of core UML state machines by primitives that designate the location of objects and their moves within a network. Our contribution is twofold: first, we formalize the semantics of state machines in MTLA, an extension of Lamport’s Temporal Logic of Actions with spatial modalities. Second, we study refinement concepts for state machines that are semantically justified in MTLA
Polarizability of ultracold molecules in the rovibrational ground state of
We study, both theoretically and experimentally, the dynamical polarizability
of molecules in the rovibrational ground state
of . Taking all relevant excited molecular bound states
into account, we compute the complex-valued polarizability for
wave numbers up to . Our calculations are compared to
experimental results at () as
well as at (). Here, we
discuss the measurements at . The ultracold
molecules are trapped in the lowest Bloch band of a 3D optical
lattice. Their polarizability is determined by lattice modulation spectroscopy
which measures the potential depth for a given light intensity. Moreover, we
investigate the decay of molecules in the optical lattice, where lifetimes of
more than are observed. In addition, the dynamical
polarizability for the state is calculated. We provide
simple analytical expressions that reproduce the numerical results for
for all vibrational levels of as well
as . Precise knowledge of the molecular polarizability
is essential for designing experiments with ultracold molecules as lifetimes
and lattice depths are key parameters. Specifically the wavelength at
is of interest, since here, ultrastable high power
lasers are available.Comment: 22 pages, 10 figure