153 research outputs found
Micromotion-Synchronized Pulsed Doppler Cooling of Trapped Ions
We propose and demonstrate a new method for Doppler cooling trapped-ion
crystals where the distribution of micromotion amplitudes may be large and
uneven. The technique uses pulses of Doppler cooling light synchronized with
the trap RF that selectively target ions when their velocity is near a node,
leading to more uniform cooling across a crystal by a single tone of cooling
light. We lay out a theoretical framework that describes where this technique
is practical, and provide a simple experimental demonstration
Special Section Guest Editorial: Detectors for Astronomy and Cosmology
This guest editorial summarizes the Special Section on Detectors for Astronomy and Cosmology
Higgs boson hadronic branching ratios at the ILC
We present a study of the Higgs boson decay branching ratios to ,
and gluons, one of the cornerstones of the physics program at the
International Linear Collider (ILC). A standard model Higgs boson of 120\,GeV
mass, produced in the Higgs-strahlung process at \,GeV was
investigated using the full detector simulation and reconstruction procedures.
The analysis was performed in the framework of the Silicon Detector (SiD)
concept with full account of inclusive standard model backgrounds. The selected
decay modes contained two heavy flavour jets in the final state and required
excellent flavour tagging through precise reconstruction of interaction and
decay vertices in the detector. A new signal discrimination technique using
correlations of neural network outputs was used to determine the branching
ratios and estimate their uncertainties, 4.8\%, 8.4\% and 12.2\% for
, and gluons respectively.Comment: 9 Pages, 5 figures and 5 table
Two-photon amplitude interferometry for precision astrometry
Improved quantum sensing of photon wave-functions could provide high
resolution observations in the optical benefiting numerous fields, including
general relativity, dark matter studies, and cosmology. It has been recently
proposed that stations in optical interferometers would not require a
phase-stable optical link if instead sources of quantum-mechanically entangled
pairs could be provided to them, potentially enabling hitherto prohibitively
long baselines. A new refinement of this idea is developed, in which two
photons from different sources are interfered at two separate and decoupled
stations, requiring only a slow classical information link between them. We
rigorously calculate the observables and contrast this new interferometric
technique with the Hanbury Brown & Twiss intensity interferometry. We argue
this technique could allow robust high-precision measurements of the relative
astrometry of the two sources. A basic calculation suggests that angular
precision on the order of as could be achieved in a single night's
observation of two bright stars.Comment: 18 pages, 4 figures; submitted to Physical Review
Spectral characterization of a SPDC source with a fast broadband spectrometer
Knowing the properties of the single photons produced in a Spontaneous
Parametric Down-Conversion (SPDC) source can be crucial for specific
applications and uses. In particular, the spectral properties are of key
relevance. Here, we investigate a commercial SPDC source using our fast
broadband spectrometer. Our analysis is a valid method for other SPDC sources,
as well as other single-photon generation techniques, thus providing a good
example of how to use this spectrometer design. We calibrate the spectrometer
using known lines of the argon emission spectrum. We show that the two
down-converted photons from the SPDC source have different spectral properties
depending on the pump power, and in which condition we measured spectrally
similar down-converted photons. Lastly, we were able to reconstruct and
investigate the spectral information for the pump photon
Astrometry in two-photon interferometry using Earth rotation fringe scan
Optical interferometers may not require a phase-stable optical link between
the stations if instead sources of quantum-mechanically entangled pairs could
be provided to them, enabling long baselines. We developed a new variation of
this idea, proposing that photons from two different astronomical sources could
be interfered at two decoupled stations. Interference products can then be
calculated in post-processing or requiring only a slow, classical connection
between stations. In this work, we investigated practical feasibility of this
approach. We developed a Bayesian analysis method for the earth rotation fringe
scanning technique and showed that in the limit of high signal-to-noise ratio
it reproduced the results from a simple Fisher matrix analysis. We identify
candidate stair pairs in the northern hemisphere, where this technique could be
applied. With two telescopes with an effective collecting area of
m, we could detect fringing and measure the astrometric separation of the
sources at as precision in a few hours of observations, in
agreement with previous estimates
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