6,105 research outputs found
A survey of non-prehensible pneumatic manipulation surfaces : principles, models and control.
International audienceMany manipulation systems using air flow have been proposed for object handling in a non-prehensile way and without solid-to-solid contact. Potential applications include high-speed transport of fragile and clean products and high-resolution positioning of thin delicate objects. This paper discusses a comprehensive survey of state-of-the-art pneumatic manipulation from the macro scale to the micro scale. The working principles and actuation methods of previously developed air-bearing surfaces, ultra-sonic bearing surfaces, air-flow manipulators, air-film manipulators, and tilted air-jet manipulators are reviewed with a particular emphasis on the modeling and the control issues. The performance of the previously developed devices are compared quantitatively and open problems in pneumatic manipulation are discussed
Coherent manipulation of atomic qubits in optical micropotentials
We experimentally demonstrate the coherent manipulation of atomic states in
far-detuned dipole traps and registers of dipole traps based on two-dimensional
arrays of microlenses. By applying Rabi, Ramsey, and spin-echo techniques, we
systematically investigate the dephasing mechanisms and determine the coherence
time. Simultaneous Ramsey measurements in up to 16 dipole traps are performed
and proves the scalability of our approach. This represents an important step
in the application of scalable registers of atomic qubits for quantum
information processing. In addition, this system can serve as the basis for
novel atomic clocks making use of the parallel operation of a large number of
individual clocks each remaining separately addressable.Comment: to be published in Appl. Phys.
2-DOF Contactless Distributed Manipulation Using Superposition of Induced Air Flows.
International audienceMany industries require contactless transport and positioning of delicate or clean objects such as silicon wafers, glass sheets, solar cell or flat foodstuffs. The authors have presented a new form of contactless distributed manipulation using induced air flow. Previous works concerned the evaluation of the maximal velocity of transported objects and one degreeof- freedom position control of objects. This paper introduces an analytic model of the velocity field of the induced air flow according to the spatial configuration of vertical air jets. Then two degrees-of-freedom position control is investigated by exploiting the linearity property of the model. Finally the model is validated under closed-loop control and the performances of the position control are evaluated
Finite Controllability of Infinite-Dimensional Quantum Systems
Quantum phenomena of interest in connection with applications to computation
and communication almost always involve generating specific transfers between
eigenstates, and their linear superpositions. For some quantum systems, such as
spin systems, the quantum evolution equation (the Schr\"{o}dinger equation) is
finite-dimensional and old results on controllability of systems defined on on
Lie groups and quotient spaces provide most of what is needed insofar as
controllability of non-dissipative systems is concerned. However, in an
infinite-dimensional setting, controlling the evolution of quantum systems
often presents difficulties, both conceptual and technical. In this paper we
present a systematic approach to a class of such problems for which it is
possible to avoid some of the technical issues. In particular, we analyze
controllability for infinite-dimensional bilinear systems under assumptions
that make controllability possible using trajectories lying in a nested family
of pre-defined subspaces. This result, which we call the Finite Controllability
Theorem, provides a set of sufficient conditions for controllability in an
infinite-dimensional setting. We consider specific physical systems that are of
interest for quantum computing, and provide insights into the types of quantum
operations (gates) that may be developed.Comment: This is a much improved version of the paper first submitted to the
arxiv in 2006 that has been under review since 2005. A shortened version of
this paper has been conditionally accepted for publication in IEEE
Transactions in Automatic Control (2009
3-DOF potential air flow manipulation by inverse modeling control.
International audiencePotential air flows can be used to perform nonprehensile contactless manipulations of objects gliding on airhockey table. In this paper, we introduce a general method able to perform 3-DOF position control of an object with potential air flow manipulators. This approach is based on an inverse modeling control scheme to perform closed-loop position servoing. We propose to use a linear programming algorithm to determine which sinks have to be activated in order to produce the suitable potential air flow to obtain the desired object motion. This approach is then validated on an experimental manipulator
Imprinting Patterns of Neutral Atoms in an Optical Lattice using Magnetic Resonance Techniques
We prepare arbitrary patterns of neutral atoms in a one-dimensional (1D)
optical lattice with single-site precision using microwave radiation in a
magnetic field gradient. We give a detailed account of the current limitations
and propose methods to overcome them. Our results have direct relevance for
addressing of planes, strings or single atoms in higher dimensional optical
lattices for quantum information processing or quantum simulations with
standard methods in current experiments. Furthermore, our findings pave the way
for arbitrary single qubit control with single site resolution.Comment: 9 pages, 7 figure
A Stark decelerator on a chip
A microstructured array of 1254 electrodes on a substrate has been configured
to generate an array of local minima of electric field strength with a
periodicity of 120 m about 25 m above the substrate. By applying
sinusoidally varying potentials to the electrodes, these minima can be made to
move smoothly along the array. Polar molecules in low-field seeking quantum
states can be trapped in these traveling potential wells. Recently, we
experimentally demonstrated this by transporting metastable CO molecules at
constant velocities above the substrate [Phys. Rev. Lett. 100 (2008) 153003].
Here, we outline and experimentally demonstrate how this microstructured array
can be used to decelerate polar molecules directly from a molecular beam. For
this, the sinusoidally varying potentials need to be switched on when the
molecules arrive above the chip, their frequency needs to be chirped down in
time, and they need to be switched off before the molecules leave the chip
again. Deceleration of metastable CO molecules from an initial velocity of 360
m/s to a final velocity as low as 240 m/s is demonstrated in the 15-35 mK deep
potential wells above the 5 cm long array of electrodes. This corresponds to a
deceleration of almost , and about 85 cm of kinetic energy is
removed from the metastable CO molecules in this process.Comment: 17 pages, 6 figure
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