37 research outputs found
Dissipative quantum control of a spin chain
A protocol is discussed for preparing a spin chain in a generic many-body
state in the asymptotic limit of tailored non-unitary dynamics. The dynamics
require the spectral resolution of the target state, optimized coherent pulses,
engineered dissipation, and feedback. As an example, we discuss the preparation
of an entangled antiferromagnetic state, and argue that the procedure can be
applied to chains of trapped ions or Rydberg atoms.Comment: 5 pages, 4 figure
Cavity sideband cooling of a single trapped ion
We report a demonstration and quantitative characterization of
one-dimensional cavity cooling of a single trapped 88Sr+ ion in the resolved
sideband regime. We measure the spectrum of cavity transitions, the rates of
cavity heating and cooling, and the steady-state cooling limit. The cavity
cooling dynamics and cooling limit of 22.5(3) motional quanta, limited by the
moderate coupling between the ion and the cavity, are consistent with a simple
model [Phys. Rev. A 64, 033405] without any free parameters, validating the
rate equation model for cavity cooling.Comment: 5 pages, 4 figure
Non dissipative decoherence of Rabi oscillations
We present a simple theoretical description of two recent experiments where
damping of Rabi oscillations, which cannot be attributed to dissipative
decoherence, has been observed. This is obtained considering the evolution time
or the Hamiltonian as random variables and then averaging the usual unitary
evolution on a properly defined, model-independent, probability distribution.Comment: 4 pages, RevTe
Resonant coupling of a Bose-Einstein condensate to a micromechanical oscillator
We report experiments in which the vibrations of a micromechanical oscillator
are coupled to the motion of Bose-condensed atoms in a trap. The interaction
relies on surface forces experienced by the atoms at about one micrometer
distance from the mechanical structure. We observe resonant coupling to several
well-resolved mechanical modes of the condensate. Coupling via surface forces
does not require magnets, electrodes, or mirrors on the oscillator and could
thus be employed to couple atoms to molecular-scale oscillators such as carbon
nanotubes.Comment: 9 pages, 4 figure
Suppression of Heating Rates in Cryogenic Surface-Electrode Ion Traps
Dense arrays of trapped ions provide one way of scaling up ion trap quantum
information processing. However, miniaturization of ion traps is currently
limited by sharply increasing motional state decoherence at sub-100 um
ion-electrode distances. We characterize heating rates in cryogenically cooled
surface-electrode traps, with characteristic sizes in 75 um to 150 um range.
Upon cooling to 6 K, the measured rates are suppressed by 7 orders of
magnitude, two orders of magnitude below previously published data of similarly
sized traps operated at room temperature. The observed noise depends strongly
on fabrication process, which suggests further improvements are possible.Comment: 4 pages, 4 figure