5,402 research outputs found
Unsupervised Pretraining Encourages Moderate-Sparseness
It is well known that direct training of deep neural networks will generally
lead to poor results. A major progress in recent years is the invention of
various pretraining methods to initialize network parameters and it was shown
that such methods lead to good prediction performance. However, the reason for
the success of pretraining has not been fully understood, although it was
argued that regularization and better optimization play certain roles. This
paper provides another explanation for the effectiveness of pretraining, where
we show pretraining leads to a sparseness of hidden unit activation in the
resulting neural networks. The main reason is that the pretraining models can
be interpreted as an adaptive sparse coding. Compared to deep neural network
with sigmoid function, our experimental results on MNIST and Birdsong further
support this sparseness observation.Comment: 6 pages, 2 figures, (to appear) ICML-Workshop on Unsupervised
Learning from Bioacoustic Big Data (uLearnBio) 201
New Generalization of Perturbed Ostrowski Type Inequalities and Applications
Generalizations of Ostrowski type inequality for functions of Lipschitzian
type are established. Applications in numerical integration and cumulative
distribution functions are also given.Comment: 11 pages
Topological superradiant state in Fermi gases with cavity induced spin-orbit coupling
Coherently driven atomic gases inside optical cavities hold great promise for
generating rich dynamics and exotic states of matter. It was shown recently
that an exotic topological superradiant state exists in a two-component
degenerate Fermi gas coupled to a cavity, where local order parameters coexist
with global topological invariants. In this work, we characterize in detail
various properties of this exotic state, focusing on the feedback interactions
between the atoms and the cavity field. In particular, we demonstrate that
cavity-induced interband coupling plays a crucial role in inducing the
topological phase transition between the conventional and topological
superradiant states. We analyze the interesting signatures in the cavity field
left by the closing and reopening of the atomic bulk gap across the topological
phase boundary and discuss the robustness of the topological superradiant state
by investigating the steady-state phase diagram under various conditions.
Furthermore, we consider the interaction effect and discuss the interplay
between the pairing order in atomic ensembles and the superradiance of the
cavity mode. Our work provides many valuable insights into the unique
cavity--atom hybrid system under study and is helpful for future experimental
exploration of the topological superradiant state.Comment: 12 pages+10 figure
Modulation of single-photon-level wave packets with two-component electromagnetically induced transparency
Coherent manipulation of single-photon wave packets is essentially important
for optical quantum communication and quantum information processing. In this
paper, we realize controllable splitting and modulation of single-photon-level
pulses by using a tripod-type atomic medium. The adoption of two control beams
enable us to store one signal pulse into superposition of two distinct atomic
collective excitations. By controlling the time delay between the two control
pulses, we observe splitting of a stored wave packet into two
temporally-distinct modes. By controlling the frequency detuning of the control
beams, we observe both temporal and frequency-domain interference of the
retrieval signal pulses, which provides a method for pulse modulation and
multi-splitting of the signal photons.Comment: 5 pages, 4 figure
Highly Retrievable Spinwave-Photon Entanglement Source
Entanglement between a single photon and a quantum memory forms the building
blocks for quantum repeater and quantum network. Previous entanglement sources
are typically with low retrieval efficiency, which limits future larger-scale
applications. Here, we report a source of highly retrievable spinwave-photon
entanglement. Polarization entanglement is created through interaction of a
single photon with ensemble of atoms inside a low-finesse ring cavity. The
cavity is engineered to be resonant for dual spinwave modes, which thus enables
efficient retrieval of the spinwave qubit. An intrinsic retrieval efficiency up
to 76(4)% has been observed. Such a highly retrievable atom-photon entanglement
source will be very useful in future larger-scale quantum repeater and quantum
network applications.Comment: 5 pages, 3 figure
TruthDiscover: Resolving Object Conflicts on Massive Linked Data
Considerable effort has been made to increase the scale of Linked Data.
However, because of the openness of the Semantic Web and the ease of extracting
Linked Data from semi-structured sources (e.g., Wikipedia) and unstructured
sources, many Linked Data sources often provide conflicting objects for a
certain predicate of a real-world entity. Existing methods cannot be trivially
extended to resolve conflicts in Linked Data because Linked Data has a
scale-free property. In this demonstration, we present a novel system called
TruthDiscover, to identify the truth in Linked Data with a scale-free property.
First, TruthDiscover leverages the topological properties of the Source Belief
Graph to estimate the priori beliefs of sources, which are utilized to smooth
the trustworthiness of sources. Second, the Hidden Markov Random Field is
utilized to model interdependencies among objects for estimating the trust
values of objects accurately. TruthDiscover can visualize the process of
resolving conflicts in Linked Data. Experiments results on four datasets show
that TruthDiscover exhibits satisfactory accuracy when confronted with data
having a scale-free property.Comment: This paper had been accepted by Proceedings of the 26th International
Conference on World Wide Web Companion. International World Wide Web
Conferences Steering Committee, 2017, WWW201
Freezing motion-induced dephasing in an atomic-ensemble quantum memory
Motion-induced dephasing is a dominant decoherence mechanism for atom-gas
quantum memories. In this paper, we develop a new coherent manipulation
technique which enables arbitrary engineering of the spin-wave momentum with
neglectable noise. By zeroing the spin-wave momentum, motion-induced dephasing
can be frozen completely. We experimentally demonstrate this scheme with
laser-cooled atoms in a DLCZ configuration. By applying the freezing pulses,
memory lifetime gets extended significantly to the limit of atom cloud
expansion and does not depend on the detection angle anymore. The observed high
cross-correlation above 20 proves that high-fidelity memory operation is well
preserved after coherent manipulation.Comment: 4 pages, 4 figure
Symmetry aspects of the pion leptoproduction and the upper limit of the Levelt-Mulders asymmetry
We examined the symmetry aspect of the semi-inclusive one-pion production in
the deep inelastic scattering of a lepton beam off an unpolarized nucleon
target, with an emphasis on the positivity restrictions on the corresponding
structure functions. In combination with the Callan-Gross-type relation between
two twist-two structure functions and , we derived an upper bound on
the Levelt-Mulders asymmetry, which occurs when the lepton beam is
longitudinally polarized.Comment: 8 pages, final version to appear in Z. Phys. C, completely rephrase
Semi-Deterministic Entanglement between a Single Photon and an Atomic Ensemble
Entanglement between a single photon and a matter qubit is an indispensable
resource for quantum repeater and quantum networks. With atomic ensembles, the
entanglement creation probability is typically very low to inhibit high-order
events. In this paper, we propose and experimentally realize a scheme which
creates atom-photon entanglement with an intrinsic efficiency of 50%. We make
use of Rydberg blockade to generate two collective excitations, lying in
separate internal states. By introducing the momentum degree of freedom for the
excitations, and interfering them via Raman coupling, we entangle the two
excitations. Via retrieving one excitation, we create the entanglement between
the polarization of a single photon and the momentum of the remaining atomic
excitation, with a measured fidelity of 0.901(8). The retrieved optical field
is verified to be genuine single photons. The realized entanglement may be
employed to create entanglement between two distant nodes in a fully heralded
way and with a much higher efficiency.Comment: 8 pages, 7 figure
Constituent quark number scaling from strange hadron spectra in collisions at 13 TeV
We show that the data of spectra of and at
midrapidity in inelastic events in collisions at 13 TeV
exhibit a constituent quark number scaling property, which is a clear signal of
quark combination mechanism at hadronization. We use a quark combination model
under equal velocity combination approximation to systematically study the
production of identified hadrons in collisions at = 13 TeV. The
midrapidity data of spectra of proton, , ,
, and in inelastic events are simultaneously well
fitted by the model. The data of multiplicity dependency of yields of these
hadrons are also well understood. The strong dependence for data of
ratio is well explained by the model, which further suggests that the
production of two hadrons with similar masses is determined by their quark
contents at hadronization. spectra of strange hadrons at midrapidity in
different multiplicity classes in collisions at 13 TeV are
predicted to further test the model in the future. The midrapidity
spectra of soft ( GeV/c) strange quark and up/down quark at
hadronization in collisions at 13 TeV are extracted.Comment: 13 pages, 14 figure
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