3,791 research outputs found
Scaling and Suppression of Anomalous Heating in Ion Traps
We measure and characterize anomalous motional heating of an atomic ion confined in the lowest quantum levels of a novel rf ion trap that features moveable electrodes. The scaling of heating with electrode proximity is measured, and when the electrodes are cooled from 300 to 150 K, the heating rate is suppressed by an order of magnitude. This provides direct evidence that anomalous motional heating of trapped ions stems from microscopic noisy potentials on the electrodes that are thermally driven. These observations are relevant to decoherence in quantum information processing schemes based on trapped ions and perhaps other charge-based quantum systems
Bell inequality violation with two remote atomic qubits
We observe violation of a Bell inequality between the quantum states of two
remote Yb ions separated by a distance of about one meter with the detection
loophole closed. The heralded entanglement of two ions is established via
interference and joint detection of two emitted photons, whose polarization is
entangled with each ion. The entanglement of remote qubits is also
characterized by full quantum state tomography.Comment: 4 pages, 4 figure
Abelian Sandpile Model on the Husimi Lattice of Square Plaquettes
An Abelian sandpile model is considered on the Husimi lattice of square
plaquettes. Exact expressions for the distribution of height probabilities in
the Self-Organized Critical state are derived. The two-point correlation
function for the sites deep inside the Husimi lattice is calculated exactly.Comment: 12 pages, LaTeX, source files and some additional information
available at http://thsun1.jinr.dubna.su/~shcher
Decoherence in ion traps due to laser intensity and phase fluctuations
We consider one source of decoherence for a single trapped ion due to
intensity and phase fluctuations in the exciting laser pulses. For simplicity
we assume that the stochastic processes involved are white noise processes,
which enables us to give a simple master equation description of this source of
decoherence. This master equation is averaged over the noise, and is sufficient
to describe the results of experiments that probe the oscillations in the
electronic populations as energy is exchanged between the internal and
electronic motion. Our results are in good qualitative agreement with recent
experiments and predict that the decoherence rate will depend on vibrational
quantum number in different ways depending on which vibrational excitation
sideband is used.Comment: 2 figures, submitted to PR
Ion trap transducers for quantum electromechanical oscillators
An enduring challenge for contemporary physics is to experimentally observe
and control quantum behavior in macroscopic systems. We show that a single
trapped atomic ion could be used to probe the quantum nature of a mesoscopic
mechanical oscillator precooled to 4K, and furthermore, to cool the oscillator
with high efficiency to its quantum ground state. The proposed experiment could
be performed using currently available technology.Comment: 4 pages, 2 figure
Unitary transformation approach for the trapped ion dynamics
We present a way of treating the problem of the interaction of a single
trapped ion with laser beams based on successive aplications of unitary
transformations onto the Hamiltonian. This allows the diagonalization of the
Hamiltonian, by means of recursive relations, without performing the Lamb-Dicke
approximation.Comment: 8 page
“It’s one rule for them and one for us”: Occupational classification, gender, and worktime domestic labour
Mo-Al{sub 2}O{sub 3} cermet research and development
This report describes the results to date of a program that was initiated to predict and measure residual stresses in Mo-Al{sub 2}O{sub 3} cermet-containing components and to develop new materials and processes that would lead to the reduction or elimination of the thermal mismatch stresses. The period of performance includes work performed CY95-97. Excessive thermal mismatch stresses had produced cracking in some cermet-containing neutron tube components. This cracking could lead to a loss of hermeticity or decreased tube reliability. Stress predictions were conducted using finite element models of the various components, along with the thermal coefficient of expansion (CTE), Young`s modulus, and strength properties. A significant portion of the program focused on the property measurements for the existing cermet materials, processing conditions, and the measurement technique. The effects of differences in the properties on the predicted residual stresses were calculated for existing designs. Several potential approaches were evaluated for reducing the residual stresses and cracking in cermet-containing parts including reducing the Mo content of the cermet, substituting a ternary alloy with a better CTE match with alumina, and substituting Nb for Mo. Processing modifications were also investigated for minimizing warpage that occurs during sintering due to differential sintering. These modifications include changing the pressing of the 94ND2 alumina and changing to a 96% alumina powder from AlSiMag
Implementation of quantum gates and preparation of entangled states in cavity QED with cold trapped ions
We propose a scheme to perform basic gates of quantum computing and prepare
entangled states in a system with cold trapped ions located in a single mode
optical cavity. General quantum computing can be made with both motional state
of the trapped ion and cavity state being qubits. We can also generate
different kinds of entangled states in such a system without state reduction,
and can transfer quantum states from the ion in one trap to the ion in another
trap. Experimental requirement for achieving our scheme is discussed.Comment: To appear in J. Opt.
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