144 research outputs found
Unsupervised Learning of Style-sensitive Word Vectors
This paper presents the first study aimed at capturing stylistic similarity
between words in an unsupervised manner. We propose extending the continuous
bag of words (CBOW) model (Mikolov et al., 2013) to learn style-sensitive word
vectors using a wider context window under the assumption that the style of all
the words in an utterance is consistent. In addition, we introduce a novel task
to predict lexical stylistic similarity and to create a benchmark dataset for
this task. Our experiment with this dataset supports our assumption and
demonstrates that the proposed extensions contribute to the acquisition of
style-sensitive word embeddings.Comment: 7 pages, Accepted at The 56th Annual Meeting of the Association for
Computational Linguistics (ACL 2018
Nitrogen isotope effects on boron vacancy quantum sensors in hexagonal boron nitride
Recently, there has been growing interest in researching the use of hexagonal
boron nitride (hBN) for quantum technologies. Here we investigate nitrogen
isotope effects on boron vacancy (V) defects, one of the candidates
for quantum sensors, in N isotopically enriched hBN synthesized using
metathesis reaction. The Raman shifts are scaled with the reduced mass,
consistent with previous work on boron isotope enrichment. We obtain nitrogen
isotopic composition dependent optically detected magnetic resonance spectra of
V defects and determine the hyperfine interaction parameter of
N spin to be -64 MHz. Our investigation provides a design policy for
hBNs for quantum technologies
Demonstration of geometric diabatic control of quantum states
Geometric effects can play a pivotal role in streamlining quantum
manipulation. We demonstrate a geometric diabatic control, that is, perfect
tunneling between spin states in a diamond by a quadratic sweep of a driving
field. The field sweep speed for the perfect tunneling is determined by the
geometric amplitude factor and can be tuned arbitrarily. Our results are
obtained by testing a quadratic version of Berry's twisted Landau-Zener model.
This geometric tuning is robust over a wide parameter range. Our work provides
a basis for quantum control in various systems, including condensed matter
physics, quantum computation, and nuclear magnetic resonance
Wide-field quantitative magnetic imaging of superconducting vortices using perfectly aligned quantum sensors
Various techniques have been applied to visualize superconducting vortices,
providing clues to their electromagnetic response. Here, we present a
wide-field, quantitative imaging of the stray field of the vortices in a
superconducting thin film using perfectly aligned diamond quantum sensors. Our
analysis, which mitigates the influence of the sensor inhomogeneities,
visualizes the magnetic flux of single vortices in YBaCuO
with an accuracy of . The obtained vortex shape is consistent with
the theoretical model, and penetration depth and its temperature dependence
agree with previous studies, proving our technique's accuracy and broad
applicability. This wide-field imaging, which in principle works even under
extreme conditions, allows the characterization of various superconductors
Optical-power-dependent splitting of magnetic resonance in nitrogen-vacancy centers in diamond
Nitrogen-vacancy (NV) centers in diamonds are a powerful tool for accurate
magnetic field measurements. The key is precisely estimating the
field-dependent splitting width of the optically detected magnetic resonance
(ODMR) spectra of the NV centers. In this study, we investigate the optical
power dependence of the ODMR spectra using NV ensemble in nanodiamonds (NDs)
and a single-crystal bulk diamond. We find that the splitting width
exponentially decays and is saturated as the optical power increases.
Comparison between NDs and a bulk sample shows that while the decay amplitude
is sample-dependent, the optical power at which the decay saturates is almost
sample-independent. We propose that this unexpected phenomenon is an intrinsic
property of the NV center due to non-axisymmetry deformation or impurities. Our
finding indicates that diamonds with less deformation are advantageous for
accurate magnetic field measurements.Comment: 9 pages, 7 figure
Ordered Counterfactual Explanation by Mixed-Integer Linear Optimization
Post-hoc explanation methods for machine learning models have been widely
used to support decision-making. One of the popular methods is Counterfactual
Explanation (CE), also known as Actionable Recourse, which provides a user with
a perturbation vector of features that alters the prediction result. Given a
perturbation vector, a user can interpret it as an "action" for obtaining one's
desired decision result. In practice, however, showing only a perturbation
vector is often insufficient for users to execute the action. The reason is
that if there is an asymmetric interaction among features, such as causality,
the total cost of the action is expected to depend on the order of changing
features. Therefore, practical CE methods are required to provide an
appropriate order of changing features in addition to a perturbation vector.
For this purpose, we propose a new framework called Ordered Counterfactual
Explanation (OrdCE). We introduce a new objective function that evaluates a
pair of an action and an order based on feature interaction. To extract an
optimal pair, we propose a mixed-integer linear optimization approach with our
objective function. Numerical experiments on real datasets demonstrated the
effectiveness of our OrdCE in comparison with unordered CE methods.Comment: 20 pages, 5 figures, to appear in the 35th AAAI Conference on
Artificial Intelligence (AAAI 2021
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