409 research outputs found
On the manipulability of dual cooperative robots
The definition of manipulability ellipsoids for dual robot systems is given. A suitable kineto-static formulation for dual cooperative robots is adopted which allows for a global task space description of external and internal forces, and relative velocities. The well known concepts of force and velocity manipulability ellipsoids for a single robot are formally extended and the contributions of the two single robots to the cooperative system ellipsoids are illustrated. Duality properties are discussed. A practical case study is developed
New Experimental Constraints on Non-Newtonian Forces below 100 microns
We have searched for large deviations from Newtonian gravity by means of a
microcantilever-based Cavendish-style experiment. Our data eliminate from
consideration mechanisms of deviation that posit strengths ~10^4 times
Newtonian gravity at length scales of 20 microns. This measurement is 3 orders
of magnitude more sensitive than others that provide constraints at similar
length scales.Comment: 4 pages, 4 figure
An ion trap built with photonic crystal fibre technology
We demonstrate a surface-electrode ion trap fabricated using techniques
transferred from the manufacture of photonic-crystal fibres. This provides a
relatively straightforward route for realizing traps with an electrode
structure on the 100 micron scale with high optical access. We demonstrate the
basic functionality of the trap by cooling a single ion to the quantum ground
state, allowing us to measure a heating rate from the ground state of 787(24)
quanta/s. Variation of the fabrication procedure used here may provide access
to traps in this geometry with trap scales between 100 um and 10 um.Comment: 6 pages, 4 figure
T-junction ion trap array for two-dimensional ion shuttling, storage and manipulation
We demonstrate a two-dimensional 11-zone ion trap array, where individual
laser-cooled atomic ions are stored, separated, shuttled, and swapped. The trap
geometry consists of two linear rf ion trap sections that are joined at a 90
degree angle to form a T-shaped structure. We shuttle a single ion around the
corners of the T-junction and swap the positions of two crystallized ions using
voltage sequences designed to accommodate the nontrivial electrical potential
near the junction. Full two-dimensional control of multiple ions demonstrated
in this system may be crucial for the realization of scalable ion trap quantum
computation and the implementation of quantum networks.Comment: 3 pages, 5 figure
Resource Requirements for Fault-Tolerant Quantum Simulation: The Transverse Ising Model Ground State
We estimate the resource requirements, the total number of physical qubits
and computational time, required to compute the ground state energy of a 1-D
quantum Transverse Ising Model (TIM) of N spin-1/2 particles, as a function of
the system size and the numerical precision. This estimate is based on
analyzing the impact of fault-tolerant quantum error correction in the context
of the Quantum Logic Array (QLA) architecture. Our results show that due to the
exponential scaling of the computational time with the desired precision of the
energy, significant amount of error correciton is required to implement the TIM
problem. Comparison of our results to the resource requirements for a
fault-tolerant implementation of Shor's quantum factoring algorithm reveals
that the required logical qubit reliability is similar for both the TIM problem
and the factoring problem.Comment: 19 pages, 8 figure
A microfabricated surface-electrode ion trap for scalable quantum information processing
We demonstrate confinement of individual atomic ions in a radio-frequency
Paul trap with a novel geometry where the electrodes are located in a single
plane and the ions confined above this plane. This device is realized with a
relatively simple fabrication procedure and has important implications for
quantum state manipulation and quantum information processing using large
numbers of ions. We confine laser-cooled Mg-24 ions approximately 40 micrometer
above planar gold electrodes. We measure the ions' motional frequencies and
compare them to simulations. From measurements of the escape time of ions from
the trap, we also determine a heating rate of approximately five motional
quanta per millisecond for a trap frequency of 5.3 MHz.Comment: 4 pages, 4 figure
Cavity QED in a molecular ion trap
We propose an approach for studying quantum information and performing high
resolution spectroscopy of rotational states of trapped molecular ions using an
on-chip superconducting microwave resonator. Molecular ions have several
advantages over neutral molecules. Ions can be loaded into deep (1 eV) RF traps
and are trapped independent of the electric dipole moment of their rotational
transition. Their charge protects them from motional dephasing and prevents
collisional loss, allowing 1 s coherence times when used as a quantum memory,
with detection of single molecules possible in <10 ms. An analysis of the
detection efficiency and coherence properties of the molecules is presented.Comment: 9 pages, 1 figur
Cryogenic Ion Trapping Systems with Surface-Electrode Traps
We present two simple cryogenic RF ion trap systems in which cryogenic
temperatures and ultra high vacuum pressures can be reached in as little as 12
hours. The ion traps are operated either in a liquid helium bath cryostat or in
a low vibration closed cycle cryostat. The fast turn around time and
availability of buffer gas cooling made the systems ideal for testing
surface-electrode ion traps. The vibration amplitude of the closed cycled
cryostat was found to be below 106 nm. We evaluated the systems by loading
surface-electrode ion traps with Sr ions using laser ablation, which
is compatible with the cryogenic environment. Using Doppler cooling we observed
small ion crystals in which optically resolved ions have a trapped lifetime
over 2500 minutes.Comment: 10 pages, 13 EPS figure
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