220 research outputs found
Two-dimensional rare-earth Janus 2-Gd (,=Cl, Br, I, ) monolayers: Bipolar ferro-magnetic semiconductors with high Curie temperature and large valley polarization
Two-dimensional (2D) ferromagnetic semiconductors show great interest due to
their potential applications for the nanoscale electronic devices. In this
work, the Janus 2-Gd (, =Cl, Br, I, ) monolayers with
rare-earth element Gd (4+5) are predicted by the first-principles
calculations. Small exfoliation energy of less than 0.25 J/m and
excellent dynamical/thermal stabilities can be confirmed for the Janus
2-Gd monolayers, which exhibit the bipolar magnetic semiconductor
character with high Curie temperatures above 260 K and large spin-orbit
coupling effect, and can be further transformed into the half-semiconductor
phase under proper tensile strains (5-6\%). In addition, the in-plane magnetic
anisotropy can be observed in the 2-GdICl and 2-GdIBr monolayers. On the
contrary, the 2-GdBrCl monolayer exhibits perpendicular magnetic anisotropy
character, which originates from the competition between Gd-/ and halogen
atom- orbitals. Calculated valley optical actions of the Janus 2-Gd
monolayers exhibit distinguished valley-selective circular dichroisms, which is
expected to realize the special valley excitation by polarized light.
Spontaneously valley-Zeeman effect in the valance band for the Janus
2-Gd monolayers induces a giant valley splitting of 60-120 meV, which is
also robust against various external biaxial strains. Tunable valley degree of
freedom in the Janus 2-Gd systems is very necessary for encoding and
processing information.Comment: 8 pages, 8 figure
Attention-Aware Face Hallucination via Deep Reinforcement Learning
Face hallucination is a domain-specific super-resolution problem with the
goal to generate high-resolution (HR) faces from low-resolution (LR) input
images. In contrast to existing methods that often learn a single
patch-to-patch mapping from LR to HR images and are regardless of the
contextual interdependency between patches, we propose a novel Attention-aware
Face Hallucination (Attention-FH) framework which resorts to deep reinforcement
learning for sequentially discovering attended patches and then performing the
facial part enhancement by fully exploiting the global interdependency of the
image. Specifically, in each time step, the recurrent policy network is
proposed to dynamically specify a new attended region by incorporating what
happened in the past. The state (i.e., face hallucination result for the whole
image) can thus be exploited and updated by the local enhancement network on
the selected region. The Attention-FH approach jointly learns the recurrent
policy network and local enhancement network through maximizing the long-term
reward that reflects the hallucination performance over the whole image.
Therefore, our proposed Attention-FH is capable of adaptively personalizing an
optimal searching path for each face image according to its own characteristic.
Extensive experiments show our approach significantly surpasses the
state-of-the-arts on in-the-wild faces with large pose and illumination
variations
2-D Compass Codes
The compass model on a square lattice provides a natural template for
building subsystem stabilizer codes. The surface code and the Bacon-Shor code
represent two extremes of possible codes depending on how many gauge qubits are
fixed. We explore threshold behavior in this broad class of local codes by
trading locality for asymmetry and gauge degrees of freedom for stabilizer
syndrome information. We analyze these codes with asymmetric and spatially
inhomogeneous Pauli noise in the code capacity and phenomenological models. In
these idealized settings, we observe considerably higher thresholds against
asymmetric noise. At the circuit level, these codes inherit the bare-ancilla
fault-tolerance of the Bacon-Shor code.Comment: 10 pages, 7 figures, added discussion on fault-toleranc
Composite Disturbance Filtering: A Novel State Estimation Scheme for Systems With Multi-Source, Heterogeneous, and Isomeric Disturbances
State estimation has long been a fundamental problem in signal processing and
control areas. The main challenge is to design filters with ability to reject
or attenuate various disturbances. With the arrival of big data era, the
disturbances of complicated systems are physically multi-source, mathematically
heterogenous, affecting the system dynamics via isomeric (additive,
multiplicative and recessive) channels, and deeply coupled with each other. In
traditional filtering schemes, the multi-source heterogenous disturbances are
usually simplified as a lumped one so that the "single" disturbance can be
either rejected or attenuated. Since the pioneering work in 2012, a novel state
estimation methodology called {\it composite disturbance filtering} (CDF) has
been proposed, which deals with the multi-source, heterogenous, and isomeric
disturbances based on their specific characteristics. With the CDF, enhanced
anti-disturbance capability can be achieved via refined quantification,
effective separation, and simultaneous rejection and attenuation of the
disturbances. In this paper, an overview of the CDF scheme is provided, which
includes the basic principle, general design procedure, application scenarios
(e.g. alignment, localization and navigation), and future research directions.
In summary, it is expected that the CDF offers an effective tool for state
estimation, especially in the presence of multi-source heterogeneous
disturbances
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