24 research outputs found
Floquet Analysis of Atom Optics Tunneling Experiments
Dynamical tunneling has been observed in atom optics experiments by two
groups. We show that the experimental results are extremely well described by
time-periodic Hamiltonians with momentum quantized in units of the atomic
recoil. The observed tunneling has a well defined period when only two Floquet
states dominate the dynamics. Beat frequencies are observed when three Floquet
states dominate. We find frequencies which match those observed in both
experiments. The dynamical origin of the dominant Floquet states is identified.Comment: Accepted in Physical Review
Multiple Bifurcations in atom optics
We report the observation of multiple bifurcations in a nonlinear Hamiltionian system: laser-cooled atoms in a standing wave with single-frequency intensity modulation. We provide clear evidence of the occurrence of bifurcations by analyzing the atomic momentum distributions
Signatures of chaotic tunnelling
Recent experiments with cold atoms provide a significant step toward a better
understanding of tunnelling when irregular dynamics is present at the classical
level. In this paper, we lay out numerical studies which shed light on the
previous experiments, help to clarify the underlying physics and have the
ambition to be guidelines for future experiments.Comment: 11 pages, 9 figures, submitted to Phys. Rev. E. Figures of better
quality can be found at http://www.phys.univ-tours.fr/~mouchet
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Experimental system design for the integration of trapped-ion and superconducting qubit systems
We present a design for the experimental integration of ion trapping and superconducting qubit systems as a step towards the realization of a quantum hybrid system. The scheme addresses two key difficulties in realizing such a system: a combined microfabricated ion trap and superconducting qubit architecture, and the experimental infrastructure to facilitate both technologies. Developing upon work by Kielpinski et al. (Phys Rev Lett 108(13):130504, 2012. doi:10.1103/PhysRevLett.108.130504), we describe the design, simulation and fabrication process for a microfabricated ion trap capable of coupling an ion to a superconducting microwave LC circuit with a coupling strength in the tens of kHz. We also describe existing difficulties in combining the experimental infrastructure of an ion trapping set-up into a dilution refrigerator with superconducting qubits and present solutions that can be immediately implemented using current technology
Spatially-resolved potential measurement with ion crystals
We present a method to measure potentials over an extended region using
one-dimensional ion crystals in a radio frequency (RF) ion trap. The
equilibrium spacings of the ions within the crystal allow the determination of
the external forces acting at each point. From this the overall potential, and
also potentials due to specific trap features, are calculated. The method can
be used to probe potentials near proximal objects in real time, and can be
generalized to higher dimensions.Comment: 7 pages (double spaced), 3 figure
Quantum Chaos Versus Classical Chaos: Why is Quantum Chaos Weaker?
We discuss the questions: How to compare quantitatively classical chaos with
quantum chaos? Which one is stronger? What are the underlying physical reasons
Optimum electrode configurations for fast ion separation in microfabricated surface ion traps
For many quantum information implementations with trapped ions, effective
shuttling operations are important. Here we discuss the efficient separation
and recombination of ions in surface ion trap geometries. The maximum speed of
separation and recombination of trapped ions for adiabatic shuttling operations
depends on the secular frequencies the trapped ion experiences in the process.
Higher secular frequencies during the transportation processes can be achieved
by optimising trap geometries. We show how two different arrangements of
segmented static potential electrodes in surface ion traps can be optimised for
fast ion separation or recombination processes. We also solve the equations of
motion for the ion dynamics during the separation process and illustrate
important considerations that need to be taken into account to make the process
adiabatic
Nonlinearity effects in the kicked oscillator
The quantum kicked oscillator is known to display a remarkable richness of
dynamical behaviour, from ballistic spreading to dynamical localization. Here
we investigate the effects of a Gross Pitaevskii nonlinearity on quantum
motion, and provide evidence that the qualitative features depend strongly on
the parameters of the system.Comment: 4 pages, 5 figure
Transport of charged particles by adjusting rf voltage amplitudes
We propose a planar architecture for scalable quantum information processing
(QIP) that includes X-junctions through which particles can move without
micromotion. This is achieved by adjusting radio frequency (rf) amplitudes to
move an rf null along the legs of the junction. We provide a proof-of-principle
by transporting dust particles in three dimensions via adjustable rf potentials
in a 3D trap. For the proposed planar architecture, we use regularization
techniques to obtain amplitude settings that guarantee smooth transport through
the X-junction.Comment: 16 pages, 10 figure
Chaos and flights in the atom-photon interaction in cavity QED
We study dynamics of the atom-photon interaction in cavity quantum
electrodynamics (QED), considering a cold two-level atom in a single-mode
high-finesse standing-wave cavity as a nonlinear Hamiltonian system with three
coupled degrees of freedom: translational, internal atomic, and the field. The
system proves to have different types of motion including L\'{e}vy flights and
chaotic walkings of an atom in a cavity. It is shown that the translational
motion, related to the atom recoils, is governed by an equation of a parametric
nonlinear pendulum with a frequency modulated by the Rabi oscillations. This
type of dynamics is chaotic with some width of the stochastic layer that is
estimated analytically. The width is fairly small for realistic values of the
control parameters, the normalized detuning and atomic recoil
frequency . It is demonstrated how the atom-photon dynamics with a
given value of depends on the values of and initial
conditions. Two types of L\'{e}vy flights, one corresponding to the ballistic
motion of the atom and another one corresponding to small oscillations in a
potential well, are found. These flights influence statistical properties of
the atom-photon interaction such as distribution of Poincar\'{e} recurrences
and moments of the atom position . The simulation shows different regimes of
motion, from slightly abnormal diffusion with at to a superdiffusion with at that
corresponds to a superballistic motion of the atom with an acceleration. The
obtained results can be used to find new ways to manipulate atoms, to cool and
trap them by adjusting the detuning .Comment: 16 pages, 7 figures. To be published in Phys. Rev.