6,343 research outputs found
Characterization of high-dimensional entangled systems via mutually unbiased measurements
Mutually unbiased bases (MUBs) play a key role in many protocols in quantum
science, such as quantum key distribution. However, defining MUBs for arbitrary
high-dimensional systems is theoretically difficult, and measurements in such
bases can be hard to implement. We show experimentally that efficient quantum
state reconstruction of a high-dimensional multi-partite quantum system can be
performed by considering only the MUBs of the individual parts. The state
spaces of the individual subsystems are always smaller than the state space of
the composite system. Thus, the benefit of this method is that MUBs need to be
defined for the small Hilbert spaces of the subsystems rather than for the
large space of the overall system. This becomes especially relevant where the
definition or measurement of MUBs for the overall system is challenging. We
illustrate this approach by implementing measurements for a high-dimensional
system consisting of two photons entangled in the orbital angular momentum
(OAM) degree of freedom, and we reconstruct the state of this system for
dimensions of the individual photons from d=2 to 5.Comment: 8 page
Creepy (not KREEPy) Gold-Indium Intermetallic Compounds on Secondary Ion Mass Spectrometry Samples
A series of Secondary Ion Mass Spectrometry (SIMS) sessions to measure hydrogen (H) in Martian meteorite minerals was completed using the Cameca 6f SIMS and NanoSIMS 50L at Arizona State University (ASU). During these sessions, a creeping phenomenon has occurred, where the edges of samples pressed in indium are covered by a metal alloy. We summarize these observations herein, present a collection of preliminary data, and discuss explanations and concerns for future SIMS work. We conclude the report with a research plan for further study
On the modulation instability development in optical fiber systems
Extensive numerical simulations were performed to investigate all stages of
modulation instability development from the initial pulse of pico-second
duration in photonic crystal fiber: quasi-solitons and dispersive waves
formation, their interaction stage and the further propagation. Comparison
between 4 different NLS-like systems was made: the classical NLS equation, NLS
system plus higher dispersion terms, NLS plus higher dispersion and
self-steepening and also fully generalized NLS equation with Raman scattering
taken into account. For the latter case a mechanism of energy transfer from
smaller quasi-solitons to the bigger ones is proposed to explain the dramatical
increase of rogue waves appearance frequency in comparison to the systems when
the Raman scattering is not taken into account.Comment: 9 pages, 54 figure
On the statistical interpretation of optical rogue waves
Numerical simulations are used to discuss various aspects of "optical rogue
wave" statistics observed in noise-driven fiber supercontinuum generation
associated with highly incoherent spectra. In particular, we consider how long
wavelength spectral filtering influences the characteristics of the statistical
distribution of peak power, and we contrast the statistics of the spectrally
filtered SC with the statistics of both the peak power of the most red-shifted
soliton in the SC and the maximum peak power across the full temporal field
with no spectral selection. For the latter case, we show that the unfiltered
statistical distribution can still exhibit a long-tail, but the extreme-events
in this case correspond to collisions between solitons of different
frequencies. These results confirm the importance of collision dynamics in
supercontinuum generation. We also show that the collision-induced events
satisfy an extended hydrodynamic definition of "rogue wave" characteristics.Comment: Paper accepted for publication in the European Physical Journal ST,
Special Topics. Discussion and Debate: Rogue Waves - towards a unifying
concept? To appear 201
A Multi-Sims Investigation of Water Content and D/H Ratios in Roberts Massif 04262 with Insight to Sources of Hydrogen in Maskelynite
We want to define the H2O content ([H2O]) and hydrogen (H) isotope composition of meteoritic material from Mars [1-3] with motivation to understand Mars volatile history, constrain geochemical signatures of interior water reservoirs (i.e. the Martian mantle) and explore effects of planetary (e.g. planet formation, magma ocean degassing) and local (e.g. volcanic degassing, impact melting and degassing) processes on H incorporated in minerals. Secondary ion mass spectrometry (SIMS) allows multiple avenues to address these questions. However, application to (1) precious astromaterials and (2) low level H measurements, pose specific challenges that are further complicated when combined. We present preliminary data of a multi-approach (SIMS vs. NanoSIMS) study of H in Roberts Massif 04262 (RBT 04262), an enriched lherzolitic shergottite with nonpoikilitic (NP) and poikilitic (P) lithologies [4]. We analyze olivine, pyrox-ene, and melt inclusions to compare indigenous mantle water, with impact-generated maskelynite to investigate H signatures due to shock
Learning Arbitrary Statistical Mixtures of Discrete Distributions
We study the problem of learning from unlabeled samples very general
statistical mixture models on large finite sets. Specifically, the model to be
learned, , is a probability distribution over probability
distributions , where each such is a probability distribution over . When we sample from , we do not observe
directly, but only indirectly and in very noisy fashion, by sampling from
repeatedly, independently times from the distribution . The problem is
to infer to high accuracy in transportation (earthmover) distance.
We give the first efficient algorithms for learning this mixture model
without making any restricting assumptions on the structure of the distribution
. We bound the quality of the solution as a function of the size of
the samples and the number of samples used. Our model and results have
applications to a variety of unsupervised learning scenarios, including
learning topic models and collaborative filtering.Comment: 23 pages. Preliminary version in the Proceeding of the 47th ACM
Symposium on the Theory of Computing (STOC15
The Impact of Proposed Corporate Tax Reform on Closely Held Corporations
Mr. Shaw\u27s presentation emphasizes the need to focus attention on the difficulties the proposed rules may cause when selling stock in small corporations and argues that the repeal of General Utilities may be more burdensome to the closely held corporation where the assets distributed in a complete liquidation may be ordinary and not capital gain assets, thus increasing the cost of liquidation to an amount higher than 50%, and the search for non-corporate entities for conducting business. However, Mr. Shaw sees the proposed changes as aiding the small corporation, in avoiding complexity, and generally having a better chance of coping with the tax Structure. Mr. Lang discusses some of the problems in the day-to-day life span of a closely held corporation and provides a chronology of key events that occur in the various phases of a corporate business
Chalcogenide-glass polarization-maintaining photonic crystal fiber for mid-infrared supercontinuum generation
In this paper, we report the design and fabrication of a highly birefringent
polarization-maintaining photonic crystal fiber (PM-PCF) made from chalcogenide
glass, and its application to linearly-polarized supercontinuum (SC) generation
in the mid-infrared region. The PM fiber was drawn using the casting method
from As38Se62 glass which features a transmission window from 2 to 10
and a high nonlinear index of 1.13.10mW. It has a
zero-dispersion wavelength around 4.5 and, at this wavelength, a large
birefringence of 6.10 and consequently strong polarization maintaining
properties are expected. Using this fiber, we experimentally demonstrate
supercontinuum generation spanning from 3.1-6.02 and 3.33-5.78
using femtosecond pumping at 4 and 4.53 , respectively. We
further investigate the supercontinuum bandwidth versus the input pump
polarization angle and we show very good agreement with numerical simulations
of the two-polarization model based on two coupled generalized nonlinear
Schr\"odinger equations.Comment: 13 pages, 8 figure
Fundamental noise limitations to supercontinuum generation in microstructure fiber
Broadband noise on supercontinuum spectra generated in microstructure fiber
is shown to lead to amplitude fluctuations as large as 50 % for certain input
laser pulse parameters. We study this noise using both experimental
measurements and numerical simulations with a generalized stochastic nonlinear
Schroedinger equation, finding good quantitative agreement over a range of
input pulse energies and chirp values. This noise is shown to arise from
nonlinear amplification of two quantum noise inputs: the input pulse shot noise
and the spontaneous Raman scattering down the fiber.Comment: 16 pages with 6 figure
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