1,642 research outputs found
C3AE: Exploring the Limits of Compact Model for Age Estimation
Age estimation is a classic learning problem in computer vision. Many larger
and deeper CNNs have been proposed with promising performance, such as AlexNet,
VggNet, GoogLeNet and ResNet. However, these models are not practical for the
embedded/mobile devices. Recently, MobileNets and ShuffleNets have been
proposed to reduce the number of parameters, yielding lightweight models.
However, their representation has been weakened because of the adoption of
depth-wise separable convolution. In this work, we investigate the limits of
compact model for small-scale image and propose an extremely Compact yet
efficient Cascade Context-based Age Estimation model(C3AE). This model
possesses only 1/9 and 1/2000 parameters compared with MobileNets/ShuffleNets
and VggNet, while achieves competitive performance. In particular, we re-define
age estimation problem by two-points representation, which is implemented by a
cascade model. Moreover, to fully utilize the facial context information,
multi-branch CNN network is proposed to aggregate multi-scale context.
Experiments are carried out on three age estimation datasets. The
state-of-the-art performance on compact model has been achieved with a
relatively large margin.Comment: accepted by cvpr201
Entangled state engineering of vibrational modes in a multi-membrane optomechanical system
We propose a method to generate entangled states of the vibrational modes of
N membranes which are coupled to a cavity mode via the radiation pressure.
Using sideband excitations, we show that arbitrary entangled states of
vibrational modes of different membranes can be produced in principle by
sequentially applying a series of classical pulses with desired frequencies,
phases and durations. As examples, we show how to synthesize several typical
entangled states, for example, Bell states, NOON states, GHZ states and W
states. The environmental effect, information leakage, and experimental
feasibility are briefly discussed. Our proposal can also be applied to other
experimental setups of optomechanical systems, in which many mechanical
resonators are coupled to a common sing-mode cavity field via the radiation
pressure.Comment: 15 pages, 10 figure
Phononic Josephson oscillation and self-trapping with two-phonon exchange interaction
We propose a bosonic Josephson junction (BJJ) in two nonlinear mechanical
resonator coupled through two-phonon exchange interaction induced by quadratic
optomechanical couplings. The nonlinear dynamic equations and effective
Hamiltonian are derived to describe behaviors of the BJJ. We show that the BJJ
can work in two different dynamical regimes: Josephson oscillation and
macroscopic self-trapping. The system can transfer from one regime to the other
one when the self-interaction and asymmetric parameters exceed their critical
values. We predict that a transition from Josephson oscillation to macroscopic
self-trapping can be induced by the phonon damping in the asymmetric BJJs. Our
results opens up a way to demonstrate BJJ with two-phonon exchange interaction
and can be applied to other systems, such as the optical and microwave systems.Comment: 7 pages, 7 figure
Engineering of nonclassical motional states in optomechanical systems
We propose to synthesize arbitrary nonclassical motional states in
optomechanical systems by using sideband excitations and photon blockade. We
first demonstrate that the Hamiltonian of the optomechanical systems can be
reduced, in the strong single-photon optomechanical coupling regime when the
photon blockade occurs, to one describing the interaction between a driven
two-level trapped ion and the vibrating modes, and then show a method to
generate target states by using a series of classical pulses with desired
frequencies, phases, and durations. We further analyze the effect of the photon
leakage, due to small anharmonicity, on the fidelity of the expected motional
state, and study environment induced decoherence. Moreover, we also discuss the
experimental feasibility and provide operational parameters using the possible
experimental data.Comment: 11 pages, 4 figure
From blockade to transparency: controllable photon transmission through a circuit QED system
A strong photon-photon nonlinear interaction is a necessary condition for
photon blockade. Moreover, this nonlinearity can also result a bistable
behavior in the cavity field. We analyze the relation between detecting field
and photon blockade in a superconducting circuit QED system, and show that
photon blockade cannot occur when the detecting field is in the bistable
regime. This photon blockade is the microwave-photonics analog of the Coulomb
blockade. We further demonstrate that the photon transmission through such
system can be controlled (from photon blockade to transparency) by the
detecting field. Numerical calculations show that our proposal is
experimentally realizable with current technology.Comment: 7 papes, 5 figure
Image Ordinal Classification and Understanding: Grid Dropout with Masking Label
Image ordinal classification refers to predicting a discrete target value
which carries ordering correlation among image categories. The limited size of
labeled ordinal data renders modern deep learning approaches easy to overfit.
To tackle this issue, neuron dropout and data augmentation were proposed which,
however, still suffer from over-parameterization and breaking spatial
structure, respectively. To address the issues, we first propose a grid dropout
method that randomly dropout/blackout some areas of the raining image. Then we
combine the objective of predicting the blackout patches with classification to
take advantage of the spatial information. Finally we demonstrate the
effectiveness of both approaches by visualizing the Class Activation Map (CAM)
and discover that grid dropout is more aware of the whole facial areas and more
robust than neuron dropout for small training dataset. Experiments are
conducted on a challenging age estimation dataset - Adience dataset with very
competitive results compared with state-of-the-art methods.Comment: IEEE International Conference on Multimedia Expo (ICME Oral
Presentation
The origin of the Redshift Spikes in the reflection spectrum of a Few-cycle Pulse in a Dense Medium
We give a detailed description about the reflected spectrum of a few-cycle
pulse propagating through a resonant dense medium. An unexpected low-frequency
spike appeared in the red edge of the spectrum. To figure out the origin of
this redshift spike, we analysis the mechanisms responsible for the redshift of
the reflected field. So far, the redshift has not been well studied for
few-cycle pulses except a brief explanation made by the previous study
[Kaloshan et al., Phys. Rev. Lett. 83 544 (1999).], which attributed the origin
of the redshift to the so-called intrapulse four-wave mixing. However, we
demonstrate numerically that the redshift consists of two separated spikes is
actually produced by the Doppler effect of backpropagation waves, which is an
analogue effect of dynamic nonlinear optical skin effect. Our study elucidates
the underlying physics of the dynamic nonlinear optical effects responsible for
the redshift spikes. Moreover, the dependency of the their frequency on the
laser and medium parameters, such as medium density and input pulse area are
also discussed
Mechanical PT symmetry in coupled optomechanical systems
We propose to realize mechanical parity-time PT symmetry in two coupled
optomechanical systems. To provide gain to one mechanical resonator and the
same amount of damping to the other, the two optical cavities should be driven
by blue- and red-detuned laser fields, respectively. After adiabatically
eliminating the degrees of freedom of the cavity modes, we derive a formula to
describe the PT symmetry of two coupled mechanical resonators. Mechanical
PT-symmetric phase transition is demonstrated by the dynamical behavior of the
mechanical resonators. Moreover, we study the effect of the quantum noises on
the dynamical behavior of the mechanical resonators when the system is in the
quantum regime.Comment: 12 pages, 11 figure
Single-photon nonreciprocal transport in one-dimensional coupled-resonator waveguides
We study the transport of a single photon in two coupled one-dimensional
semi-infinite coupled-resonator waveguides (CRWs), in which both end sides are
coupled to a dissipative cavity. We demonstrate that a single photon can
transfer from one semi-infinite CRW to the other nonreciprocally. Based on such
nonreciprocity, we further construct a three-port single-photon circulator by a
T-shaped waveguide, in which three semi-infinite CRWs are pairwise mutually
coupled to each other. The single-photon nonreciprocal transport is induced by
the breaking of the time-reversal symmetry and the optimal conditions for these
phenomena are obtained analytically. The CRWs with broken time-reversal
symmetry will open up a kind of quantum devices with versatile applications in
quantum networks.Comment: 10 pages, 6 figure
Nonreciprocal conversion between microwave and optical photons in electro-optomechanical systems
We propose to demonstrate nonreciprocal conversion between microwave and
optical photons in an electro-optomechanical system where a microwave mode and
an optical mode are coupled indirectly via two non-degenerate mechanical modes.
The nonreciprocal conversion is obtained in the broken time-reversal symmetry
regime, where the conversion of photons from one frequency to the other is
enhanced for constructive quantum interference while the conversion in the
reversal direction is suppressed due to destructive quantum interference. It is
interesting that the nonreciprocal response between the microwave and optical
modes in the electro-optomechanical system appears at two different frequencies
with opposite directions. The proposal can be used to realize nonreciprocal
conversion between photons of any two distinctive modes with different
frequencies. Moreover, the electro-optomechanical system can also be used to
construct a three-port circulator for three optical modes with distinctively
different frequencies by adding an auxiliary optical mode coupled to one of the
mechanical modes.Comment: 10 pages, 4 figure
- …