Faculty
Publications: January, 2009
Query Results from the Smithsonian/NASA
Astrophysics Data System (ADS)
| Title: |
Exploring entanglement
in the context of quantum sensing |
| Authors: |
Myers, J.M.; Wu,
Tai Tsun |
| Publication: |
Proceedings of the
SPIE - The International Society for Optical
Engineering, Vol. 7342: 734206 (01 Jan. 2009). |
| Publication
Date: |
01/2009 |
| Origin: |
SPIE |
| Keywords: |
cosmology: theory,
intergalactic medium |
| DOI: |
10.1117/12.818723 |
Abstract: Motivated by an
interest in quantum sensing, we define carefully a degree
of entanglement, starting with bipartite pure states
and building up to a definition applicable to any mixed
state on any tensor product of finite-dimensional vector
spaces. For mixed states the degree of entanglement is
defined in terms of a minimum over all possible decompositions
of the mixed state into pure states. Using a variational
analysis we show a property of minimizing decompositions.
Combined with data about the given mixed state, this
property determines the degrees of entanglement of a
given mixed state. For pure or mixed states symmetric
under permutation of particles, we show that no partial
trace can increase the degree of entanglement. For selected
less-than-maximally-entangled pure states, we quantify
the degree of entanglement surviving a partial trace.
| Title: |
Probing Reionization
with the 21 CM Galaxy Cross-Power Spectrum |
| Authors: |
Lidz, Adam; Zahn, Oliver; Furlanetto, Steven R.; McQuinn, Matthew; Hernquist, Lars; Zaldarriaga, Matias |
| Publication: |
The Astrophysical
Journal, Volume 690, Issue 1, pp. 252-266 (2009).
(ApJ
Homepage) |
| Publication
Date: |
01/2009 |
| Origin: |
IOP |
| Keywords: |
cosmology: theory,
intergalactic medium, large-scale structure of
universe |
| DOI: |
10.1088/0004-637X/690/1/252 |
| Bibliographic
Code: |
2009ApJ...690..252L |
Abstract:
The cross-correlation between high-redshift galaxies
and 21 cm emission from the high-redshift intergalactic
medium promises to be an excellent probe of the Epoch
of Reionization. On large scales, the 21 cm and galaxy
fields are anticorrelated during most of the reionization
epoch. However, on scales smaller than the size of the
H II regions around detectable galaxies, the two fields
become roughly uncorrelated. Consequently, the 21 cm
galaxy cross-power spectrum provides a tracer of bubble
growth during reionization, with the signal turning over
on progressively larger scales as reionization proceeds.
The precise turnover scale depends on the minimum host
mass of the detectable galaxies, and the galaxy selection
technique. Measuring the turnover scale as a function
of galaxy luminosity constrains the characteristic bubble
size around galaxies of different luminosities. The cross-spectrum
becomes positive on small scales if ionizing photons
fail to escape from low-mass galaxies, and these galaxies
are detectable longward of the hydrogen ionization edge,
because in this case some identifiable galaxies lie outside
the ionized regions. The Murchison Widefield Array (MWA)
and Low Frequency Array can potentially measure the 21
cm galaxy cross-spectrum in conjunction with mild extensions
to the existing Subaru survey for z = 6.6 Lyα emitters.
A futuristic galaxy survey covering a sizable fraction
of the MWA field of view (~800 deg2) can probe the scale
dependence of the cross-spectrum, constraining the filling
factor of H II regions at different redshifts during
reionization, and providing other valuable constraints
on reionization models.
| Title: |
Einstein: His Life
and Universe |
| Authors: |
Isaacson, Walter; Holton, Gerald |
| Publication: |
American Journal
of Physics, Volume 77, Issue 1, pp. 95-95 (2009). |
| Publication
Date: |
01/2009 |
| Origin: |
AIP |
| Keywords: |
biographies, physics
education, reviews |
| DOI: |
10.1119/1.2985819 |
| Bibliographic
Code: |
2009AmJPh..77...95I |
Abstract:
Not Available
| Title: |
Supernova Cosmology
Results From Six Years of ESSENCE |
| Authors: |
Suntzeff, Nicholas B.; Wood-Vasey, W.; Aguilera, C.;...Stubbs, C.;...
and 33 coauthors. |
| Publication: |
American Astronomical
Society, AAS Meeting #213, #481.06 |
| Publication
Date: |
01/2009 |
| Origin: |
AAS |
| Abstract
Copyright: |
(c) 2009: American
Astronomical Society |
| Bibliographic
Code: |
2009AAS...21348106S |
Abstract:
The ESSENCE project has successfully discovered and observed
over 200 SNe Ia during 6 years of observations with the
CTIO/NOAO 4.0m telescope with spectroscopic classifications
from the Gemini, Magellan, and Keck telescopes. We are
currently facing the challenge of solving the remaining
systematic uncertainties that have been in discussion
for a decade: the proper treatment of host galaxy dust
extinction, the intrinsic SN Ia colors, and the luminosity
corrections appropriate for each. We will present our
final Hubble diagram fit to the ESSENCE data, and our
best estimate for the equation of state parameter w,
including detailed modeling of the errors, both systematic
and statistical.
| Title: |
LSST: From Science
Drivers To Reference Design And Anticipated Data
Products |
| Authors: |
Ivezic, Zeljko; Tyson, J. A.; Axelrod, T.; Burke, D.; Claver, C. F.; Cook, K. H.; Kahn, S. M.; Lupton, R. H.; Monet, D. G.; Pinto, P. A.; Strauss, M. A.; Stubbs, C. W.; Jones, L.; Saha, A.; Scranton, R.; Smith, C.; LSST Collaboration |
| Publication: |
American Astronomical
Society, AAS Meeting #213, #460.03 |
| Publication
Date: |
01/2009 |
| Origin: |
AAS |
| Abstract
Copyright: |
(c) 2009: American
Astronomical Society |
| Bibliographic
Code: |
2009AAS...21346003I |
Abstract:
The LSST will be a large, wide-field ground based telescope
designed to obtain sequential images covering the entire
visible sky from Cerro Pachon in Northern Chile. The
current baseline design, with an 8.4m (6.7m effective)
primary mirror and a 9.6 sq.deg. field of view, will
allow about 10,000 square degrees of sky to be covered
in two photometric bands every three nights (assuming
two 15-second exposures per field visit). The system
is designed to yield high image quality as well as superb
astrometric and photometric accuracy. The survey area
will include at least 25,000 sq.deg. with Dec < +34.5,
and will be imaged multiple times in six bands covering
the wavelength range 320--1050 nm. The vast majority
(about 90%) of the observing time will be devoted to
a deep-wide-fast survey mode which will observe a 20,000
sq.deg. region south of Dec +10 deg in the ugrizy bands
about 1000 times (including all bands) during the 10-year
survey. The deep-wide-fast survey data will serve the
majority of science programs. The remaining 10% of observing
time will be allocated to special programs such as Very
Deep and Very Fast time domain surveys. We illustrate
how LSST science drivers led to these choices of system
design parameters.
| Title: |
The E and B EXperiment
(EBEX); Progress and Status |
| Authors: |
Sagiv, Ilan; Aboobaker, A. M.; Ade, P.;...; Zaldarriaga, M.;...and
37 coauthors. |
| Publication: |
American Astronomical
Society, AAS Meeting #213, #357.08 |
| Publication
Date: |
01/2009 |
| Origin: |
AAS |
| Abstract
Copyright: |
(c) 2009: American
Astronomical Society |
| Bibliographic
Code: |
2009AAS...21335708S |
Abstract:
We report on the status of EBEX, a NASA-funded balloon-borne
polarimeter designed to measure the B-mode polarization
of the cosmic microwave background radiation. The EBEX
receiver is designed to set a 2σ upper limit on an inflationary
tensor-to-scalar ratio of 0.02. This limit assumes a
14-day flight, a scan pattern covering 420 square degrees
of the sky, and foreground subtraction to levels below
detector noise. The instrument employs a 1.5 meter Gregorian-type
telescope and 1440 bolometric transition edge sensor
detectors distributed over two focal planes. Polarization
is measured using a rotating achromatic half wave plate
(AHWP) and a fixed polarizing grid. The AHWP is continuously
rotated using a superconducting magnetic bearing. Sky
signals will be observed in three bands centered at 150,
250 and 410 GHz, providing strong leverage against the
polarized dust foreground. Integration of the gondola
and the receiver will occur in fall 2008. A short-duration
test flight employing 384 detectors in one focal plane
is planned for 2009.
| Title: |
Molecular biology:
Concealed enzyme coordination |
| Authors: |
Abbondanzieri, Elio
A., and Xiaowei Zhuang |
| Publication: |
Nature, Volume 457,
392-393 (22 January 2009) |
| Publication
Date: |
01/2009 |
| Keywords: |
DNA; Bacteriophage-Phi-29;
Mechanisms; Rotation; Force; Motor |
| DOI: |
10.1038/457392a |
Abstract: Coordination between
subunits is crucial for the proper functioning of multi-component
molecular machines. A single-molecule study now allows
glimpses into the mechanism used by subunits of one such
machine.
| Title: |
Counselman Receives
2008 Charles A. Whitten Medal |
| Authors: |
Shapiro, Irwin; Ford, Peter G.; Counselman, Charles C. |
| Publication: |
Eos, Transactions
American Geophysical Union, Volume 90, Issue
4, p. 31-32 |
| Publication
Date: |
01/2009 |
| Origin: |
AGU |
| AGU Keywords: |
General or Miscellaneous:
Notices and announcements, Geodesy and Gravity:
Lunar and planetary geodesy and gravity (5417,
5450, 5714, 5744, 6019, 6250) |
| Abstract
Copyright: |
(c) 2009: American
Geophysical Union |
| DOI: |
10.1029/2009EO040005 |
| Bibliographic
Code: |
2009EOSTr..90...31S |
Abstract: Charles C. Counselman
III was awarded the 2008 Charles A. Whitten Medal at
the AGU Fall Meeting Honors Ceremony, held 17 December
2008 in San Francisco, Calif. The medal is for "outstanding
achievements in research on the form and dynamics of
the Earth and planets".
| Title: |
The Apache Point
Observatory Lunar Laser-ranging Operation (APOLLO):
Two Years of Millimeter-Precision Measurements
of the Earth-Moon Range |
| Authors: |
Battat, J. B. R.; Murphy, T. W., Jr.; Adelberger, E. G.; Gillespie, B.; Hoyle, C. D.; McMillan, R. J.; Michelsen, E. L.; Nordtvedt, K.; Orin, A. E.; Stubbs, C. W.; Swanson, H. E. |
| Publication: |
Publications of the
Astronomical Society of the Pacific, Vol. 121,
No. 875, p. 29-40 (2009) (PASP
Homepage) |
| Publication
Date: |
01/2009 |
| Origin: |
UCP |
| Keywords: |
Solar System |
| DOI: |
10.1086/596748 |
| Bibliographic
Code: |
2009PASP..121...29B |
Abstract: In 2006 April,
the Apache Point Observatory Lunar Laser-ranging Operation
(APOLLO) began its science campaign to measure the Earth-Moon
separation to millimeter precision. Since that time more
than 280 "normal-point" measurements have
been made of the distance between the Apache Point Observatory
(APO) 3.5-m telescope in New Mexico and retro-reflector
arrays on the surface of the Moon. If only statistical
errors are considered, then the median nightly range
measurement uncertainty for all of our data is 1.8 mm
of one-way path, and is 1.1 mm for data after 2007 September.
We present an analysis of the APOLLO system performance,
highlighting the record-breaking photon return rates
and the ability to perform high-cadence observations
of multiple lunar retro-reflector targets in a short
(30-60 minute) time span. We also show that there is
no evidence to suggest that the APOLLO apparatus introduces
drifts in the lunar-range measurement over timescales
of minutes to an hour.
Abstract: The J-matrix inverse
scattering approach can be used as an alternative to
a conventional R-matrix in analyzing scattering phase
shifts and extracting resonance energies and widths from
experimental data. A great advantage of the J-matrix
is that it provides eigenstates directly related to the
ones obtained in the shell model in a given model space
and with a given value of the oscillator spacing ℏΩ.
This relationship is of particular interest in the cases
when a many-body system does not have a resonant state
or the resonance is broad and its energy can differ significantly
from the shell-model eigenstate. We discuss the J-matrix
inverse scattering technique, extend it for the case
of charged colliding particles, and apply it to the analysis
of nα and pα scattering. The results are compared with
the no-core shell-model calculations of He5 and Li5.
Abstract: We present the
first direct experimental bound on the total decay width
of the top quark, Γ
t, using 955pb
-1 of
the Tevatron’s p&pmacr; collisions recorded by the
Collider Detector at Fermilab. We identify 253 top-antitop
pair candidate events. The distribution of reconstructed
top quark mass from these events is fitted to templates
representing different values of the top quark width.
Using a confidence interval based on likelihood-ratio
ordering, we extract an upper limit at 95% C.L. of Γ
t<13.1GeV
for an assumed top quark mass of 175GeV/c
2.
Abstract: A search for high-mass
resonances in the e
+e
- final state
is presented based on 2.5fb
-1 of s=1.96TeV
p&pmacr; collision data from the CDF II detector at the
Fermilab Tevatron. The largest excess over the standard
model prediction is at an e
+e
- invariant
mass of 240GeV/c
2. The probability of observing
such an excess arising from fluctuations in the standard
model anywhere in the mass range of 150–1000GeV/c
2 is
0.6% (equivalent to 2.5σ). We exclude the standard model
coupling Z
' and the Randall-Sundrum graviton
for k/&Mmacr;
Pl=0.1 with masses below 963
and 848GeV/c
2 at the 95% credibility level,
respectively.
Abstract: Models of maximal
flavor violation (MxFV) in elementary particle physics
may contain at least one new scalar SU(2) doublet field
Φ
FV=(η
0,η
+) that couples
the first and third generation quarks (q
1,
q
3) via a Lagrangian term L
FV=ξ
13Φ
FVq
1q
3.
These models have a distinctive signature of same-charge
top-quark pairs and evade flavor-changing limits from
meson mixing measurements. Data corresponding to 2fb
-1 collected
by the Collider Dectector at Fermilab II detector in
p&pmacr; collisions at s=1.96TeV are analyzed for evidence
of the MxFV signature. For a neutral scalar η
0 with
m
η0=200GeV/c
2 and coupling
ξ
13=1, ˜11 signal events are expected over
a background of 2.1±1.8 events. Three events are observed
in the data, consistent with background expectations,
and limits are set on the coupling ξ
13 for
m
η0=180–300GeV/c
2.
Abstract: Spin noise spectroscopy
with a single laser beam is demonstrated theoretically
to provide a direct probe of the spatial correlations
of cold fermionic gases. We show how the generic many-body
phenomena of antibunching, pairing, antiferromagnetic,
and algebraic spin liquid correlations can be revealed
by measuring the spin noise as a function of laser width,
temperature, and frequency.
Abstract: Not Available
Abstract: We present a search
for a Higgs boson decaying to two W bosons in p&pmacr;
collisions at s=1.96TeV center-of-mass energy. The data
sample corresponds to an integrated luminosity of 3.0fb
-1 collected
with the CDF II detector. We find no evidence for production
of a Higgs boson with mass between 110 and 200GeV/c
2,
and determine upper limits on the production cross section.
For the mass of 160GeV/c
2, where the analysis
is most sensitive, the observed (expected) limit is 0.7
pb (0.9 pb) at 95% Bayesian credibility level which is
1.7 (2.2) times the standard model cross section.
Abstract: Monolayers of
bimodal gold nanoparticles on silicon are investigated
by a combination of microscopy (dry monolayers) and x-ray
diffraction (dry and wet monolayers). In the presence
of an excess of small particles, the nanoscale packing
structure closely resembles the small-particle-rich scenario
of the structural crossover transition that has been
predicted and also observed with micron-scale hard-sphere
colloids. Structural morphology is monitored in situ
during monolayer dissolution and reassembly within the
thin liquid wetting film. This approach allows investigation
of size and solvent effects on nanoparticles in quasi-two-dimensional
confinement.
Abstract: We measure and
theoretically determine the effect of molecular rotational
splitting on Zeeman relaxation rates in collisions of
cold Σ3 molecules with helium atoms in a magnetic field.
All four stable isotopomers of the imidogen (NH) molecule
are magnetically trapped and studied in collisions with
He3 and He4. The He4 data support the predicted 1/Be2
dependence of the collision-induced Zeeman relaxation
rate coefficient on the molecular rotational constant
Be. The measured He3 rate coefficients are much larger
than the He4 coefficients, depend less strongly on Be,
and theoretical analysis indicates they are strongly
affected by a shape resonance. The results demonstrate
the influence of molecular structure on collisional energy
transfer at low temperatures.
Abstract: We report e
+e
-→b&bmacr;
cross section measurements by the BABAR experiment performed
during an energy scan in the range of 10.54 to 11.20
GeV at the SLAC PEP-II e
+e
- collider.
A total relative error of about 5% is reached in more
than 300 center-of-mass energy steps, separated by about
5 MeV. These measurements can be used to derive precise
information on the parameters of the Υ(10860) and Υ(11020)
resonances. In particular we show that their widths may
be smaller than previously measured.
Abstract: We present a confocal
microscopy study of 1.55μm monodisperse silica hard spheres
as they sediment and crystallize at the bottom wall of
a container. If the particles sediment onto a feature
less flat wall, the two bottom layers crystallize simultaneously
and layerwise growth follows. If the wall is replaced
by a hexagonal template, only layerwise growth occurs.
Our results complement earlier numerical simulations
and experiments on other colloidal systems.
Abstract: A search for the
lepton flavor violating decays τ
-→l
-K
S0 (l=e
or μ) has been performed using a data sample corresponding
to an integrated luminosity of 469fb
-1, collected
with the BABAR detector at the SLAC PEP-II e
+e
- asymmetric
energy collider. No statistically significant signal
has been observed in either channel and the estimated
upper limits on branching fractions are B(τ
-→e
-K
S0)<3.3×10
-8 and
B(τ
-→μ
-K
S0)<4.0×10
-8 at
90% confidence level.
| Title: |
Measurements of the
semileptonic decays &Bmacr;→Dℓν¯ and &Bmacr;→D*ℓν¯
using a global fit to DXℓν¯ final states |
| Authors: |
Aubert, B.; Bona, M.; Karyotakis, Y.;... Morii, M.;...
and 523 coauthors. |
| Publication: |
Physical Review D,
vol. 79, Issue 1, id. 012002 (PhRvD
Homepage) |
| Publication
Date: |
1/2009 |
| Origin: |
APS |
| Abstract Copyright: |
(c) 2009: The American
Physical Society |
| DOI: |
10.1103/PhysRevD.79.012002 |
| Bibliographic
Code: |
2009PhRvD..79a2002A |
Abstract: Semileptonic &Bmacr;
decays to DXℓν¯ (ℓ=e or μ) are selected by reconstructing
D
0ℓ and D
+ℓ combinations from a
sample of 230×10
6 Υ(4S)→B&Bmacr; decays recorded
with the BABAR detector at the PEP-II e
+e
- collider
at SLAC. A global fit to these samples in a three-dimensional
space of kinematic variables is used to determine the
branching fractions B(B
-→D
0ℓν¯)=(2.34±0.03±0.13)%
and B(B
-→D
*0ℓν¯)=(5.40±0.02±0.21)%
where the errors are statistical and systematic, respectively.
The fit also determines form-factor parameters in a parametrization
based on heavy quark effective theory, resulting in ρ
D2=1.20±0.04±0.07
for
&Bmacr;→Dℓν¯ and ρ
D*2=1.22±0.02±0.07
for &Bmacr;→D
*ℓν¯. These values are used to
obtain the product of the Cabibbo-Kobayashi-Maskawa matrix
element |V
cb| times the form factor at the
zero recoil point for both
&Bmacr;→Dℓν¯ decays, G(1)|V
cb|=(43.1±0.8±2.3)×10
-3,
and for &Bmacr;→D
*ℓν¯ decays, F(1)|V
cb|=(35.9±0.2±1.2)×10
-3.
| Title: |
Search for the rare
decays B+→μ+μ-K+,
B0→μ+μ-K*(892)0,
and Bs0→μ+μ-ϕ
at CDF |
| Authors: |
Aaltonen, T.; Adelman, J.; Akimoto, T.;
... Franklin, M.;
... Guimaraes da Costa, J....;
and 594 coauthors. |
| Publication: |
Physical Review D,
vol. 79, Issue 1, id. 011104 (PhRvD
Homepage) |
| Publication
Date: |
1/2009 |
| Origin: |
APS |
| Abstract Copyright: |
(c) 2009: The American
Physical Society |
| DOI: |
10.1103/PhysRevD.79.011104 |
| Bibliographic
Code: |
2009PhRvD..79a1104A |
Abstract: We search for
b→sμ
+μ
- transitions in B meson
(B
+, B
0, or B
s0)
decays with 924pb
-1 of p&pmacr; collisions
at s=1.96TeV collected with the CDF II detector at the
Fermilab Tevatron. We find excesses with significances
of 4.5, 2.9, and 2.4 standard deviations in the B
+→μ
+μ
-K
+,
B
0→μ
+μ
-K
*(892)
0,
and B
s0→μ
+μ
-ϕ
decay modes, respectively. Using B→J/ψh (h=K
+,
K
*(892)
0, ϕ) decays as normalization
channels, we report branching fractions for the previously
observed B
+ and B
0 decays, B(B
+→μ
+μ
-K
+)=(0.59±0.15±0.04)×10
-6,
and B(B
0→μ
+μ
-K
*(892)
0)=(0.81±0.30±0.10)×10
-6,
where the first uncertainty is statistical, and the second
is systematic. We set an upper limit on the relative
branching fraction B(B
s0→μ
+μ
-ϕ)/B(B
s0→J/ψϕ)<2.6(2.3)×10
-3 at
the 95(90)% confidence level, which is the most stringent
to date.
Abstract: We present measurements
of the CP-violation parameters S and C for the radiative
decay B
0→ηK
S0γ; for
B→ηKγ we also measure the branching fractions and for
B
+→ηK
+γ the time-integrated charge
asymmetry A
ch. The data, collected with the
BABAR detector at the Stanford Linear Accelerator Center,
represent 465×10
6 B&Bmacr; pairs produced
in e
+e
- annihilation. The results
are S=-0.18
-0.46+0.49±0.12, C=-0.32
-0.39+0.40±0.07,
B(B
0→ηK
0γ)=(7.1
-2.0+2.1±0.4)×10
-6,
B(B
+→ηK
+γ)=(7.7±1.0±0.4)×10
-6,
and A
ch=(-9.0
-9.8+10.4±1.4)×10
-2.
The first error quoted is statistical and the second
systematic.
Abstract: Data collected
in run II of the Fermilab Tevatron are searched for indications
of new electroweak-scale physics. Rather than focusing
on particular new physics scenarios, CDF data are analyzed
for discrepancies with the standard model prediction.
A model-independent approach (Vista) considers gross
features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided
by two additional algorithms: a Bump Hunter searches
invariant mass distributions for “bumps” that could indicate
resonant production of new particles, and the Sleuth
procedure scans for data excesses at large summed transverse
momentum. This combined global search for new physics
in 2.0fb
-1 of p&pmacr; collisions at s=1.96TeV
reveals no indication of physics beyond the standard
model.
Abstract: We describe a
technique that enables a strong coherent coupling between
a single electronic spin qubit associated with a nitrogen-vacancy
impurity in diamond and the quantized motion of a magnetized
nanomechanical resonator tip. This coupling is achieved
via careful preparation of dressed spin states which
are highly sensitive to the motion of the resonator but
insensitive to perturbations from the nuclear-spin bath.
In combination with optical pumping techniques, the coherent
exchange between spin and motional excitations enables
ground-state cooling and controlled generation of arbitrary
quantum superpositions of resonator states. Optical spin
readout techniques provide a general measurement toolbox
for the resonator with quantum limited precision.
Abstract: A nonlocal electric
response in the spin Hall regime, resulting from spin
diffusion mediating charge conduction, is predicted.
The spin-mediated transport stands out due to its long-range
character, and can give dominant contribution to nonlocal
resistance. The characteristic range of nonlocality,
set by the spin diffusion length, can be large enough
to allow detection of this effect in materials such as
GaAs despite its small magnitude. The detection is facilitated
by a characteristic nonmonotonic dependence of transresistance
on the external magnetic field, exhibiting sign changes
and decay.
| Title: |
Realization of coherent
optically dense media via buffer-gas cooling |
| Authors: |
Hong, Tao; Gorshkov, Alexey V.; Patterson, David; Zibrov, Alexander S.; Doyle, John M.; Lukin, Mikhail D.; Prentiss, Mara G. |
| Publication: |
Physical Review A,
vol. 79, Issue 1, id. 013806 (PhRvA
Homepage) |
| Publication
Date: |
01/2009 |
| Origin: |
APS |
| Abstract
Copyright: |
(c) 2009: The American
Physical Society |
| DOI: |
10.1103/PhysRevA.79.013806 |
| Bibliographic
Code: |
2009PhRvA..79a3806H |
Abstract: We demonstrate
that buffer-gas cooling combined with laser ablation
can be used to create coherent optical media with high
optical depth and low Doppler broadening that offers
metastable states with low collisional and motional decoherence.
Demonstration of this generic technique opens pathways
to coherent optics with a large variety of atoms and
molecules. We use helium buffer gas to cool Rb87 atoms
to below 7K and slow atom diffusion to the walls. Electromagnetically
induced transparency in this medium allows for 50% transmission
in a medium with initial optical depth D>70 and for
slow pulse propagation with large delay-bandwidth products.
In the high- D regime, we observe high-contrast spectrum
oscillations due to efficient four-wave mixing.
Abstract: In 2004, a combined
system test was performed in the H8 beam line at the
CERN SPS with a setup reproducing the geometry of sectors
of the ATLAS Muon Spectrometer, formed by three stations
of Monitored Drift Tubes (MDT). The full ATLAS analysis
chain was used to obtain the results presented in this
paper. The basic design performances of the Muon Spectrometer
were verified. The stability of MDT calibration constants,
the alignment system using optical devices and high energy
tracks, as well as the intrinsic sagitta resolution of
the Muon Spectrometer were studied and found to agree
with expectations. The reconstruction of muon tracks
using the combined information from both the Inner Detector
and the Muon Spectrometer are also presented.
Abstract: We demonstrate
that flavor symmetries in warped geometry can provide
a natural explanation for large mixing angles and economically
explain the distinction between the quark and lepton
flavor sectors. We show how to naturally generate Majorana
neutrino masses assuming a gauged a U(1)B‑L symmetry
broken in the UV that generates see-saw masses of the
right size. This model requires lepton minimal flavor
violation (LMFV) in which only Yukawa matrices (present
on the IR brane) break the flavor symmetries. The symmetry-breaking
is transmitted to charged lepton bulk mass parameters
as well to generate the hierarchy of charged lepton masses.
With LMFV, a GIM-like mechanism prevents dangerous flavor-changing
processes for charged leptons and permits flavor-changing
processes only in the presence of the neutrino Yukawa
interaction and are therefore suppressed when the overall
scale for the neutrino Yukawa matrix is slightly smaller
than one in units of the curvature. In this case the
theory can be consistent with a cutoff of 10 TeV and
3 TeV Kaluza-Klein masses.
Abstract: We consider realizations
of GUT models in F-theory. Adopting a bottom up approach,
the assumption that the dynamics of the GUT model can
in principle decouple from Planck scale physics leads
to a surprisingly predictive framework. An internal U(1)
hypercharge flux Higgses the GUT group directly to the
MSSM or to a flipped GUT model, a mechanism unavailable
in heterotic models. This new ingredient automatically
addresses a number of puzzles present in traditional
GUT models. The internal U(1) hyperflux allows us to
solve the doublet-triplet splitting problem, and explains
the qualitative features of the distorted GUT mass relations
for lighter generations due to the Aharanov-Bohm effect.
These models typically come with nearly exact global
symmetries which prevent bare μ terms and also forbid
dangerous baryon number violating operators. Strong curvature
around our brane leads to a repulsion mechanism for Landau
wave functions for neutral fields. This leads to large
hierarchies of the form exp(‑c/ε2γ) where c and γ are
order one parameters and ε ~ αGUT‑1MGUT/Mpl. This effect
can simultaneously generate a viably small μ term as
well as an acceptable Dirac neutrino mass on the order
of 0.5 × 10‑2±0.5 eV. In another scenario, we find a
modified seesaw mechanism which predicts that the light
neutrinos have masses in the expected range while the
Majorana mass term for the heavy neutrinos is ~ 3 × 1012±1.5
GeV. Communicating supersymmetry breaking to the MSSM
can be elegantly realized through gauge mediation. In
one scenario, the same repulsion mechanism also leads
to messenger masses which are naturally much lighter
than the GUT scale.
Abstract: Motivated by potential
phenomenological applications, we develop the necessary
tools for building GUT models in F-theory. This approach
is quite flexible because the local geometrical properties
of singularities in F-theory compactifications encode
the physical content of the theory. In particular, we
show how geometry determines the gauge group, matter
content and Yukawa couplings of a given model. It turns
out that these features are beautifully captured by a
four-dimensional topologically twisted Script N = 4 theory
which has been coupled to a surface defect theory on
which chiral matter can propagate. From the vantagepoint
of the four-dimensional topological theory, these defects
are surface operators. Specific intersection points of
these defects lead to Yukawa couplings. We also find
that the unfolding of the singularity in the F-theory
geometry precisely matches to properties of the topological
theory with a defect.
| Title: |
A New Calculation
of the Ionizing Background Spectrum and the Effects
of HeII Reionization |
| Authors: |
Faucher-Giguere, C. -A.; Lidz, A.; Zaldarriaga, M.; Hernquist, L. |
| Publication: |
eprint arXiv:0901.4554 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Astrophysics - Cosmology
and Extra-Galactic Astrophysics |
| Comment: |
25 pages plus 9 pages
of appendix, including 16 figures, submitted
to ApJ |
| Bibliographic
Code: |
2009arXiv0901.4554F |
Abstract: The ionizing background
determines the ionization balance and the thermodynamics
of the cosmic gas. It is therefore a fundamental ingredient
to theoretical and empirical studies of both the IGM
and galaxy formation. We present here a new calculation
of its spectrum that satisfies the empirical constraints
we recently obtained by combining state-of-the-art luminosity
functions and intergalactic opacity measurements. In
our preferred model, star-forming galaxies and quasars
each contribute substantially to the HI ionizing field
at z<3, with galaxies rapidly overtaking quasars at
higher redshifts as quasars become rarer. In addition
to our fiducial model, we explore the physical dependences
of the calculated background and clarify how recombination
emission contributes to the ionization rates. We find
that recombinations do not simply boost the ionization
rates by the number of reemitted ionizing photons as
many of these rapidly redshift below the ionization edges
and have a distribution of energies. A simple analytic
model that captures the main effects seen in our numerical
radiative transfer calculations is given. Finally, we
discuss the effects of HeII reionization by quasars on
both the spectrum of the ionizing background and on the
thermal history of the IGM. In regions that have yet
to be reionized, the spectrum is expected to be almost
completely suppressed immediately above 54.4 eV while
a background of higher-energy (>~0.5 keV) photons
permeates the entire universe owing to the frequency-dependence
of the photoionization cross section. We provide an analytic
model of the heat input during HeII reionization and
its effects on the temperature-density relation.
| Title: |
Extracting Spooky-activation-at-a-distance
from Considerations of Entanglement |
| Authors: |
Bruza, P. D.; Kitto, K.; Nelson, D.; McEvoy, C. |
| Publication: |
eprint arXiv:0901.4375 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Physics - Data Analysis,
Statistics and Probability, Computer Science
- Computation and Language, Quantum Physics |
| Comment: |
13 pages, 2 figures;
To appear in Proceedings of the Third Quantum
Interaction Symposium, Lecture Notes in Artificial
Intelligence, vol 5494, Springer, 2009 |
| Bibliographic
Code: |
2009arXiv0901.4375B |
Abstract: Following an early
claim by Nelson & McEvoy \cite{Nelson:McEvoy:2007}
suggesting that word associations can display `spooky
action at a distance behaviour', a serious investigation
of the potentially quantum nature of such associations
is currently underway. This paper presents a simple quantum
model of a word association system. It is shown that
a quantum model of word entanglement can recover aspects
of both the Spreading Activation equation and the Spooky-activation-at-a-distance
equation, both of which are used to model the activation
level of words in human memory.
| Title: |
Global operations
for protected quantum memories in atomic spin
lattices |
| Authors: |
Brennen, G. K.; Hammerer, K.; Jiang, L.; Lukin, M. D.; Zoller, P. |
| Publication: |
eprint arXiv:0901.3920 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Quantum Physics |
| Comment: |
16 pages, 6 figures |
| Bibliographic
Code: |
2009arXiv0901.3920B |
Abstract: Quantum information
processed in strongly correlated states of matter can
provide built in hardware protection against errors.
We may encode information in highly non local degrees
of freedom, such as using three dimensional spin lattices
for subsystem codes or two dimensional spin lattices
for topologically ordered surface codes and measurement
based codes. Recently, in [L. Jiang et al., Nature Physics
{\bf 4}, 482 (2008)] the authors showed how to manipulate
these global degrees of freedom using optical lattices
coupled to a bosonic degree of freedom via a cavity.
We elaborate on these ideas and recapitulate two approaches
to implement many body gates necessary for quantum information
processing, both relying on controlled interactions of
an ancillary cavity mode with the spin system and single
ancilla particles. The main focus of the present paper
is to analyze the effect of imperfections such a cavity
decay and collective and individual spin decoherence.
We present strategies to fight decoherence by monitoring
cavity decay and show that high gate fidelities can be
achieved in the strong coupling regime of cavity-QED
with state of the art parameters.
| Title: |
Optimal limits on
f_{NL}^{local} from WMAP 5-year data |
| Authors: |
Smith, Kendrick M.; Senatore, Leonardo; Zaldarriaga, Matias |
| Publication: |
eprint arXiv:0901.2572 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Astrophysics - Cosmology
and Extra-Galactic Astrophysics |
| Comment: |
21 pages, 7 figures |
| Bibliographic
Code: |
2009arXiv0901.2572S |
Abstract: We have applied
the optimal estimator for f_{NL}^{local} to the 5 year
WMAP data. Marginalizing over the amplitude of foreground
templates we get -4 < f_{NL}^{local} < 80 at 95%
CL. Error bars of previous (sub-optimal) analyses are
roughly 40% larger than these. The probability that a
Gaussian simulation, analyzed using our estimator, gives
a result larger in magnitude than the one we find is
7%. Our pipeline gives consistent results when applied
to the three and five year WMAP data releases and agrees
well with the results from our own sub-optimal pipeline.
We find no evidence of any residual foreground contamination.
| Title: |
Orientiholes |
| Authors: |
Denef, Frederik; Esole, Mboyo; Padi, Megha |
| Publication: |
eprint arXiv:0901.2540 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
High Energy Physics
- Theory |
| Bibliographic
Code: |
2009arXiv0901.2540D |
Abstract: By T-dualizing
space-filling D-branes in IIB orientifold compactifications
along the three non-internal spatial directions, we obtain
black hole bound states living in a universe with a gauged
spatial reflection symmetry. We call these objects orientiholes.
The gravitational entropy of various IIA orientihole
configurations provides an "experimental" estimate
of the number of vacua in various sectors of the IIB
landscape. Furthermore, basic physical properties of
orientiholes map to (sometimes subtle) microscopic features,
thus providing a useful alternative viewpoint on a number
of issues arising in D-brane model building. More generally,
we give orientihole generalizations of recently derived
wall crossing formulae, and conjecture a relation to
the topological string analogous to the OSV conjecture,
but with a linear rather than a quadratic identification
of partition functions.
| Title: |
Numerical simulation
of conformational variability in biopolymer translocation
through wide nanopores |
| Authors: |
Fyta, Maria; Melchionna, Simone; Bernaschi, Massimo; Kaxiras, Efthimios; Succi, Sauro |
| Publication: |
eprint arXiv:0901.2497 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Physics - Biological
Physics, Physics - Computational Physics |
| Comment: |
10 pages, 6 figures,
to appear in J. Stat. (2009) |
| Bibliographic
Code: |
2009arXiv0901.2497F |
Abstract: Numerical results
on the translocation of long biopolymers through mid-sized
and wide pores are presented. The simulations are based
on a novel methodology which couples molecular motion
to a mesoscopic fluid solvent. Thousands of events of
long polymers (up to 8000 monomers) are monitored as
they pass through nanopores. Comparison between the different
pore sizes shows that wide pores can host a larger number
of multiple biopolymer segments, as compared to smaller
pores. The simulations provide clear evidence of folding
quantization in the translocation process as the biopolymers
undertake multi-folded configurations, characterized
by a well-defined integer number of folds. Accordingly,
the translocation time is no longer represented by a
single-exponent power law dependence on the length, as
it is the case for single-file translocation through
narrow pores. The folding quantization increases with
the biopolymer length, while the rate of translocated
beads at each time step is linearly correlated to the
number of resident beads in the pore. Finally, analysis
of the statistics over the translocation work unravels
the importance of the hydrodynamic interactions in the
process.
| Title: |
Thermopower as a
Possible Probe of Non-Abelian Quasiparticle Statistics
in Fractional Quantum Hall Liquids |
| Authors: |
Yang, Kun; Halperin, Bertrand I. |
| Publication: |
eprint arXiv:0901.1429 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Condensed Matter
- Mesoscopic Systems and Quantum Hall Effect,
Condensed Matter - Strongly Correlated Electrons |
| Comment: |
5 pages. This paper
supersedes an earlier preprint by one of the
authors: K. Yang, arXiv:0807.3341v1 |
| Bibliographic
Code: |
2009arXiv0901.1429Y |
Abstract: We show in this
paper that thermopower is enhanced in non-Abelian quantum
Hall liquids under appropriate conditions. This is because
thermopower measures entropy per electron in the clean
limit, while the degeneracy and entropy associated with
non-Abelian quasiparticles enhance entropy when they
are present. Thus thermopower can potentially probe non-Abelian
nature of the quasiparticles, and measure their quantum
dimension.
Abstract: We present a technique
to locally and rapidly heat water drops in microfluidic
devices with microwave dielectric heating. Water absorbs
microwave power more efficiently than polymers, glass,
and oils due to its permanent molecular dipole moment
that has a large dielectric loss at GHz frequencies.
The relevant heat capacity of the system is a single
thermally isolated picoliter drop of water and this enables
very fast thermal cycling. We demonstrate microwave dielectric
heating in a microfluidic device that integrates a flow-focusing
drop maker, drop splitters, and metal electrodes to locally
deliver microwave power from an inexpensive, commercially
available 3.0 GHz source and amplifier. The temperature
of the drops is measured by observing the temperature
dependent fluorescence intensity of cadmium selenide
nanocrystals suspended in the water drops. We demonstrate
characteristic heating times as short as 15 ms to steady-state
temperatures as large as 30 degrees C above the base
temperature of the microfluidic device. Many common biological
and chemical applications require rapid and local control
of temperature, such as PCR amplification of DNA, and
can benefit from this new technique.
| Title: |
Landscape of superconducting
membranes |
| Authors: |
Denef, Frederik; Hartnoll, Sean A. |
| Publication: |
eprint arXiv:0901.1160 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
High Energy Physics
- Theory |
| Comment: |
1+34 pages. 3 figures |
| Bibliographic
Code: |
2009arXiv0901.1160D |
Abstract: The AdS/CFT correspondence
may connect the landscape of string vacua and the `atomic
landscape' of condensed matter physics. We study the
stability of a landscape of IR fixed points of N=2 large
N gauge theories in 2+1 dimensions, dual to Sasaki-Einstein
compactifications of M theory, towards a superconducting
state. By exhibiting instabilities of charged black holes
in these compactifications, we show that many of these
theories have charged operators that condense when the
theory is placed at a finite chemical potential. We compute
a statistical distribution of critical superconducting
temperatures for a subset of these theories. With a chemical
potential of one milliVolt, we find critical temperatures
ranging between 0.24 and 165 degrees Kelvin.
| Title: |
Causality and Primordial
Tensor Modes |
| Authors: |
Baumann, Daniel; Zaldarriaga, Matias |
| Publication: |
eprint arXiv:0901.0958 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Astrophysics - Cosmology
and Extra-Galactic Astrophysics, General Relativity
and Quantum Cosmology, High Energy Physics -
Phenomenology, High Energy Physics - Theory |
| Comment: |
19 pages, 7 figures |
| Bibliographic
Code: |
2009arXiv0901.0958B |
Abstract: We introduce the
real space correlation function of $B$-mode polarization
of the cosmic microwave background (CMB) as a probe of
superhorizon tensor perturbations created by inflation.
By causality, any non-inflationary mechanism for gravitational
wave production after reheating, like global phase transitions
or cosmic strings, must have vanishing correlations for
angular separations greater than the angle subtended
by the particle horizon at recombination, i.e. $\theta
\gtrsim 2^\circ$. Since ordinary $B$-modes are defined
non-locally in terms of the Stokes parameters $Q$ and
$U$ and therefore don't have to respect causality, special
care is taken to define `causal $\tilde B$-modes' for
the analysis. We compute the real space $\tilde B$-mode
correlation function for inflation and discuss its detectability
on superhorizon scales where it provides an unambiguous
test of inflationary gravitational waves. The correct
identification of inflationary tensor modes is crucial
since it relates directly to the energy scale of inflation.
Wrongly associating tensor modes from causal seeds with
inflation would imply an incorrect inference of the energy
scale of inflation. We find that the superhorizon $\tilde
B$-mode signal is above cosmic variance for the angular
range $2^\circ < \theta < 4^\circ$ and is therefore
in principle detectable. In practice, the signal will
be challenging to measure since it requires accurately
resolving the recombination peak of the $B$-mode power
spectrum. However, a future CMB satellite (CMBPol), with
noise level $\Delta_P \simeq 1\mu$K-arcmin and sufficient
resolution to efficiently correct for lensing-induced
$B$-modes, should be able to detect the signal at more
than 3$\sigma$ if the tensor-to-scalar ratio isn't smaller
than $r \simeq 0.01$.
| Title: |
Extremal limits and
black hole entropy |
| Authors: |
Carroll, Sean M.; Johnson, Matthew C.; Randall, Lisa |
| Publication: |
eprint arXiv:0901.0931 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
High Energy Physics
- Theory |
| Comment: |
10 pages, 3 figures |
| Bibliographic
Code: |
2009arXiv0901.0931C |
Abstract: Taking the extremal
limit of a non-extremal Reissner-Nordstr\"om black
hole (by externally varying the mass or charge), the
region between the inner and outer event horizons experiences
an interesting fate -- while this region is absent in
the extremal case, it does not disappear in the extremal
limit but rather approaches a patch of $AdS_2\times S^2$.
In other words, the approach to extremality is not continuous,
as the non-extremal Reissner-Nordstr\"om solution
splits into two spacetimes at extremality: an extremal
black hole and a disconnected $AdS$ space. We suggest
that the unusual nature of this limit may help in understanding
the entropy of extremal black holes.
| Title: |
Low-loss negative
refraction by laser induced magneto-electric
cross-coupling |
| Authors: |
Kästel, Jürgen; Fleischhauer, Michael; Yelin, Susanne F.; Walsworth, Ronald L. |
| Publication: |
eprint arXiv:0901.0664 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Quantum Physics,
Physics - Optics |
| Comment: |
13 pages, 15 figures |
| Bibliographic
Code: |
2009arXiv0901.0664K |
Abstract: We discuss the
feasibility of negative refraction with reduced absorption
in coherently driven atomic media. Coherent coupling
of an electric and a magnetic dipole transition by laser
fields induces magneto-electric cross-coupling and negative
refraction at dipole densities which are considerably
smaller than necessary to achieve a negative permeability.
At the same time the absorption gets minimized due to
destructive quantum interference and the ratio of negative
refraction index to absorption becomes orders of magnitude
larger than in systems without coherent cross-coupling.
The proposed scheme allows for a fine-tuning of the refractive
index. We derive a generalized expression for the impedance
of a medium with magneto-electric cross coupling and
show that impedance matching to vacuum can easily be
achieved. Finally we discuss the tensorial properties
of the medium response and derive expressions for the
dependence of the refractive index on the propagation
direction.
| Title: |
Candidates for Inelastic
Dark Matter |
| Authors: |
Cui, Yanou; Morrissey, David E.; Poland, David; Randall, Lisa |
| Publication: |
eprint arXiv:0901.0557 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
High Energy Physics
- Phenomenology |
| Comment: |
44 pages, 6 figures |
| Bibliographic
Code: |
2009arXiv0901.0557C |
Abstract: Although we have
yet to determine whether the DAMA data represents a true
discovery of new physics, among such interpretations
inelastic dark matter (IDM) can match the energy spectrum
of DAMA very well while not contradicting the results
of other direct detection searches. In this paper we
investigate the general properties that a viable IDM
candidate must have and search for simple models that
realize these properties in natural ways. We begin by
determining the regions of IDM parameter space that are
allowed by direct detection searches including DAMA,
paying special attention to larger IDM masses. We observe
that an inelastic dark matter candidate with electroweak
interactions can naturally satisfy observational constraints
while simultaneously yielding the correct thermal relic
abundance. We comment on several other proposed dark
matter explanations for the DAMA signal and demonstrate
that one of the proposed alternatives -- elastic scattering
of dark matter off electrons -- is strongly disfavored
when the modulated and unmodulated DAMA spectral data
are taken into account. We then outline the general essential
features of IDM models in which inelastic scattering
off nuclei is mediated by the exchange of a massive gauge
boson, and construct natural models in the context of
a warped extra dimension and supersymmetry.
| Title: |
Coherence and control
of quantum registers based on electronic spin
in a nuclear spin bath |
| Authors: |
Cappellaro, P.; Jiang, L.; Hodges, J. S.; Lukin, M. D. |
| Publication: |
eprint arXiv:0901.0444 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Quantum Physics |
| Bibliographic
Code: |
2009arXiv0901.0444C |
Abstract: We consider a
protocol for the control of few-qubit registers comprising
one electronic spin embedded in a nuclear spin bath.
We show how to isolate a few proximal nuclear spins from
the rest of the environment and use them as building
blocks for a potentially scalable quantum information
processor. We describe how coherent control techniques
based on magnetic resonance methods can be adapted to
these electronic-nuclear solid state spin systems, to
provide not only efficient, high fidelity manipulation
of the registers, but also decoupling from the spin bath.
As an example, we analyze feasible performances and practical
limitations in a realistic setting associated with nitrogen-vacancy
centers in diamond.
Abstract: We demonstrate
a fiber-optical switch that is activated at tiny energies
corresponding to few hundred optical photons per pulse.
This is achieved by simultaneously confining both photons
and a small laser-cooled ensemble of atoms inside the
microscopic hollow core of a single-mode photonic-crystal
fiber and using quantum optical techniques for generating
slow light propagation and large nonlinear interaction
between light beams.
| Title: |
Impact of Instrumental
Systematic Contamination on the Lensing Mass
Reconstruction using the CMB Polarization |
| Authors: |
Su, Meng; Yadav, Amit P. S.; Zaldarriaga, Matias |
| Publication: |
eprint arXiv:0901.0285 |
| Publication
Date: |
01/2009 |
| Origin: |
ARXIV |
| Keywords: |
Astrophysics |
| Comment: |
22 pages, 7 figures |
| Bibliographic
Code: |
2009arXiv0901.0285S |
Abstract: In this paper,
we study the effects of instrumental systematics on the
reconstruction of the deflection angle power spectrum
from weak lensing of Cosmic Microwave Background (CMB)
temperature and polarization observations. We consider
seven types of effects which are related to known instrumental
systematics: calibration, rotation, pointing, spin-flip,
monopole leakage, dipole leakage and quadrupole leakage.
These effects can be characterized by 11 distortion fields.
Each of these systematic effects can mimic the effective
projected matter power spectrum and hence contaminate
the lensing reconstruction. To demonstrate the effect
of these instrumental systematics, we consider two types
of experiments, one with a detector noise level for polarization
of 9.6 uK-arcmin and FWHM of 8.0', typical of upcoming
ground and balloon-based CMB experiments, and a CMBPol-like
instrument with a detector noise level for polarization
of 2.0 uK-arcmin and FWHM of 4.0', typical of future
space-based CMB experiments. For each systematics, we
consider various choices of coherence scale. Among all
the 11 systematic parameters, rotation and monopole leakage
place the most stringent requirements, while quadrupole
leakage, pointing error, and calibration are among the
least demanding. The requirements from lensing extraction
are about 1-2 orders of magnitude less stringent than
the requirements to measure the primordial B-modes with
inflationary energy scale of 1.0*10^{16} GeV. On the
other hand the requirements for lensing reconstruction
are comparable or even more stringent for some systematic
parameters than the requirements to detect primordial
B-modes with inflationary scale E_i = 3.0*10^{16} GeV.
Abstract: Microfluidic devices
can produce highly monodisperse drops at kilohertz rates
using flow-focus drop formation. We use single-layer
membrane valves to control, in real time, the dimensions
of the flow-focus drop makers. This allows drop size
and frequency to be controlled in real time and without
adjusting flow rates.
| Title: |
Calibration of LSST
Instrument and Data |
| Authors: |
Burke, David; Axelrod, T.; Bartlett, J.;
...: Stubbs, C.;...
, and 19 coauthors. |
| Publication: |
American Astronomical
Society, AAS Meeting #213, #460.18 |
| Publication
Date: |
01/2009 |
| Origin: |
AAS |
| Abstract
Copyright: |
(c) 2009: American
Astronomical Society |
| Bibliographic
Code: |
2009AAS...21346018B |
Abstract: Science studies
made by the Large Synoptic Survey Telescope will reach
record systematic limits in nearly all cases. Requirements
for precision of measured colors to 0.5% and absolute
photometry to 1% or better are particularly challenging.
Advantage will be taken of the rapid multi-epoch cadence
of the LSST survey to use stars to calibrate stability
and uniformity of astrometric and photometric data. A
new technique using a tunable laser is being developed
to calibrate the wavelength dependence of the total telescope
and camera system throughput and response. Spectroscopic
measurements of atmospheric extinction and emission will
be made continuously to allow the broad-band optical
flux observed in the instrument to be corrected to flux
at the top of the atmosphere. Repeated observations of
standard stars in the accumulated survey will be combined
with instrumental and atmospheric throughput measurements
to calibrate data releases. Observational studies with
existing telescopes and simulations are underway to validate
and optimize this strategy.
| Title: |
Limits on Anomalous
Spin-Spin Couplings between Neutrons |
| Authors: |
Alexander G. Glenday,
Claire E. Cramer, David F. Phillips, and Ronald
L. Walsworth |
| Publication: |
Physical Review Letters,
vol. 101, id. 261801 (2008) |
| Publication
Date: |
12/2008 |
| Origin: |
APS |
| Abstract
Copyright: |
(c) 2008: The American
Physical Society |
| DOI: |
10.1103/PhysRevLett.101.261801 |
Abstract: We report experimental
limits on new spin-dependent macroscopic forces between
neutrons. We measured the nuclear Zeeman frequencies
of a
3He=
129Xe maser while modulating
the nuclear spin polarization of a nearby
3He
ensemble in a separate glass cell. We place limits on
the coupling strength of neutron spin-spin interactions
mediated by light pseudoscalar particles like the axion
[g
pg
p/(4πħc)] at the
3 x 10
-7 level for interaction ranges longer
than about 40 cm. This limit is about 10
-5 the
size of the magnetic dipole-dipole interaction between
neutrons.
| Title: |
The true cyclotron
frequency for particles and ions in a Penning
trap |
| Authors: |
Gabrielse, G. |
| Publication: |
International Journal
of Mass Spectrometry, vol. 279, no. 2-3, pp.
107-112 |
| Publication
Date: |
01/2009 |
| Origin: |
AUTHOR |
| Keywords: |
Invariance theorem,
Penning trap, Mass spectrometry, Radionuclides,
Quadrupolar excitation |
| DOI: |
10.1016/j.ijms.2008.10.015 |
| Bibliographic
Code: |
2009IJMSp.279..107G |
Abstract: The true cyclotron
frequency of a particle or ion, needed for mass spectrometry
and other accurate measurements in a Penning trap, cannot
be measured directly. It is not one of the oscillation
frequencies of the trapped particle, and the three oscillation
frequencies that can be measured vary with the misalignment
and the harmonic distortion of the trap potential. Two
methods to determine the cyclotron frequency are discussed.
First, when all three eigenfrequencies of a trapped particle
can be measured, the true cyclotron frequency is given
by the prescription of the Brown-Gabrielse invariance
theorem. This prescription makes possible a surprising
number of the most accurate measurements in particle,
nuclear and atomic physics because it accounts exactly
for the lowest order electrostatic imperfections and
magnetic misalignments. Second, when less accuracy is
required, as when the masses of unstable nuclei are measured,
a single sideband frequency is often measured instead--the
frequency of a driving force that optimally couples two
of the motions of the ion in the trap. A missing theoretical
justification for this alternate method is provided using
an expansion of the same invariance theorem. A remarkable
suppression of systematic measurement errors is predicted,
showing why these are not larger than reported measurement
uncertainties, despite the contrary indication of simple
estimates.
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