33,838 research outputs found
Pressure Dependence of Wall Relaxation in Polarized He Gaseous Cells
We have observed a linear pressure dependence of longitudinal relaxation time
() at 4.2 K and 295 K in gaseous He cells made of either bare pyrex
glass or Cs/Rb-coated pyrex due to paramagnetic sites in the cell wall. The
paramagnetic wall relaxation is previously thought to be independent of He
pressure. We develop a model to interpret the observed wall relaxation by
taking into account the diffusion process, and our model gives a good
description of the data
Evaluation of heating effects on atoms trapped in an optical trap
We solve a stochastic master equation based on the theory of Savard et al. [T. A. Savard. K. M. O'Hara, and J. E. Thomas, Phys, Rev. A 56, R1095 (1997)] for heating arising from fluctuations in the trapping laser intensity. We compare with recent experiments of Ye et al. [J. Ye, D. W. Vernooy, and H. J. Kimble, Phys. Rev. Lett. 83, 4987 (1999)], and find good agreement with the experimental measurements of the distribution of trap occupancy times. The major cause of trap loss arises from the broadening of the energy distribution of the trapped atom, rather than the mean heating rate, which is a very much smaller effect
Real-time cavity QED with single atoms
We report the first measurement of the real-time evolution of the complex field amplitude brought on by single atom transits. We show the variation in time of both quadrature amplitudes (simultaneously recorded) of the light transmitted through the cavity, as well the resultant optical phase for a single atom transit event. In this particular measurement, the cavity and laser were both detuned by 10 MHz from the Cs resonance
Constraint-based sequence mining using constraint programming
The goal of constraint-based sequence mining is to find sequences of symbols
that are included in a large number of input sequences and that satisfy some
constraints specified by the user. Many constraints have been proposed in the
literature, but a general framework is still missing. We investigate the use of
constraint programming as general framework for this task. We first identify
four categories of constraints that are applicable to sequence mining. We then
propose two constraint programming formulations. The first formulation
introduces a new global constraint called exists-embedding. This formulation is
the most efficient but does not support one type of constraint. To support such
constraints, we develop a second formulation that is more general but incurs
more overhead. Both formulations can use the projected database technique used
in specialised algorithms. Experiments demonstrate the flexibility towards
constraint-based settings and compare the approach to existing methods.Comment: In Integration of AI and OR Techniques in Constraint Programming
(CPAIOR), 201
Precision spectroscopy and density-dependent frequency shifts in ultracold Sr
By varying the density of an ultracold Sr sample from cm
to cm, we make the first definitive measurement of the
density-related frequency shift and linewidth broadening of the -
optical clock transition in an alkaline earth system. In addition, we
report the most accurate measurement to date of the Sr
optical clock transition frequency. Including a detailed analysis of systematic
errors, the frequency is () Hz.Comment: 4 pages, 4 figures, 1 table. submitte
Characterization of high finesse mirrors: loss, phase shifts and mode structure in an optical cavity
An extensive characterization of high finesse optical cavities used in cavity
QED experiments is described. Different techniques in the measurement of the
loss and phase shifts associated with the mirror coatings are discussed and
their agreement shown. Issues of cavity field mode structure supported by the
dielectric coatings are related to our effort to achieve the strongest possible
coupling between an atom and the cavity.Comment: 8 pages, 4 figure
Expressed and Private Opinion Dynamics on Influence Networks with Asynchronous Updating
© 2020 IEEE. In this paper, an asynchronous discrete-time opinion dynamics model on a social influence network is considered. At each time instant, a single individual activates and updates two state variables simultaneously. The individual's new private opinion is a weighted average of her current private opinion, the expressed opinions of her neighbors, and a constant prejudice. Meanwhile, the individual's new expressed opinion is equal to her current private opinion, altered due to a pressure to conform to the public opinion as perceived by the individual, being the average expressed opinion among her neighbors. We analyze the system for social networks which are rooted, and show that if no individual holds a prejudice, then a mild assumption on the activation sequence of the individuals guarantees convergence. In particular, the expressed and private opinions of all individuals converge to the same value exponentially fast, with two lower bounds on convergence speeds based on two different assumptions on the network topology. Simulations are provided to illustrate the result, and provide support to the conjecture that the system dynamics may converge even if individuals hold an existing prejudice
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