7,108 research outputs found
Machine Learning and Irresponsible Inference: Morally Assessing the Training Data for Image Recognition Systems
Just as humans can draw conclusions responsibly or irresponsibly, so too can computers. Machine learning systems that have been trained on data sets that include irresponsible judgments are likely to yield irresponsible predictions as outputs. In this paper I focus on a particular kind of inference a computer system might make: identification of the intentions with which a person acted on the basis of photographic evidence. Such inferences are liable to be morally objectionable, because of a way in which they are presumptuous. After elaborating this moral concern, I explore the possibility that carefully procuring the training data for image recognition systems could ensure that the systems avoid the problem. The lesson of this paper extends beyond just the particular case of image recognition systems and the challenge of responsibly identifying a person’s intentions. Reflection on this particular case demonstrates the importance (as well as the difficulty) of evaluating machine learning systems and their training data from the standpoint of moral considerations that are not encompassed by ordinary assessments of predictive accuracy
Fluctuation-Driven Vortex Fractionalization in Topologically Ordered Superfluids of Cold Atoms
We have studied spin structures of fluctuation-driven fractionalized vortices
and topological spin order in 2D nematic superfluids of cold sodium atoms. Our
Monte Carlo simulations suggest a softened pi-spin disclination structure in a
half-quantum vortex when spin correlations are short ranged; in addition,
calculations indicate that a unique non-local topological spin order emerges
simultaneously as cold atoms become a superfluid below a critical temperature.
We have also estimated fluctuation-dependent critical frequencies for
half-quantum vortex nucleation in rotating optical traps and discussed probing
these excitations in experiments.Comment: 5 pages, 2 figures; revised version accepted by Europhysics Letter
A framework for evaluating automatic image annotation algorithms
Several Automatic Image Annotation (AIA) algorithms have been introduced recently, which have been found to outperform previous models. However, each one of them has been evaluated using either different descriptors, collections or parts of collections, or "easy" settings. This fact renders their results non-comparable, while we show that collection-specific properties are responsible for the high reported performance measures, and not the actual models. In this paper we introduce a framework for the evaluation of image annotation models, which we use to evaluate two state-of-the-art AIA algorithms. Our findings reveal that a simple Support Vector Machine (SVM) approach using Global MPEG-7 Features outperforms state-of-the-art AIA models across several collection settings. It seems that these models heavily depend on the set of features and the data used, while it is easy to exploit collection-specific properties, such as tag popularity especially in the commonly used Corel 5K dataset and still achieve good performance
Fermi-Bose Mixtures Near Broad Interspecies Feshbach Resonances
In this Letter we have studied dressed bound states in Fermi-Bose mixtures
near broad interspecies resonance, and implications on many-body correlations.
We present the evidence for a first order phase transition between a mixture of
Fermi gas and condensate, and a fully paired mixture where extended fermionic
molecules occupy a single pairing channel instead of forming a molecular Fermi
surface. We have further investigated the effect of Fermi surface dynamics,
pair fluctuations and discussed the validity of our results.Comment: 5 pages, 4 figure
Temporal Quantum Control with Graphene
We introduce a novel strategy for controlling the temporal evolution of a
quantum system at the nanoscale. Our method relies on the use of graphene
plasmons, which can be electrically tuned in frequency by external gates.
Quantum emitters (e.g., quantum dots) placed in the vicinity of a graphene
nanostructure are subject to the strong interaction with the plasmons of this
material, thus undergoing time variations in their mutual interaction and
quantum evolution that are dictated by the externally applied gating voltages.
This scheme opens a new path towards the realization of quantum-optics devices
in the robust solid-state environment of graphene.Comment: 5 pages, 2 figure
Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator
We investigate the action of time dependent detunings upon the excitation
inversion of a Cooper pair box interacting with a nanomechanical resonator. The
method employs the Jaynes-Cummings model with damping, assuming different decay
rates of the Cooper pair box and various fixed and t-dependent detunings. It is
shown that while the presence of damping plus constant detunings destroy the
collapse/revival effects, convenient choices of time dependent detunings allow
one to reconstruct such events in a perfect way. It is also shown that the mean
excitation of the nanomechanical resonator is more robust against damping of
the Cooper pair box for convenient values of t-dependent detunings.Comment: 11 pages, 5 figure
Construction of a polarization insensitive lens from a quasi-isotropic metamaterial slab
We propose to employ the quasiisotropic metamaterial (QIMM) slab to construct
a polarization insensitive lens, in which both E- and H-polarized waves exhibit
the same refocusing effect. For shallow incident angles, the QIMM slab will
provide some degree of refocusing in the same manner as an isotropic negative
index material. The refocusing effect allows us to introduce the ideas of
paraxial beam focusing and phase compensation by the QIMM slab. On the basis of
angular spectrum representation, a formalism describing paraxial beams
propagating through a QIMM slab is presented. Because of the negative phase
velocity in the QIMM slab, the inverse Gouy phase shift and the negative
Rayleigh length of paraxial Gaussian beam are proposed. We find that the phase
difference caused by the Gouy phase shift in vacuum can be compensated by that
caused by the inverse Gouy phase shift in the QIMM slab. If certain matching
conditions are satisfied, the intensity and phase distributions at object plane
can be completely reconstructed at image plane. Our simulation results show
that the superlensing effect with subwavelength image resolution could be
achieved in the form of a QIMM slab.Comment: 25 pages, 8 figure
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