11,168 research outputs found
Generation of frequency multiplexed entangled single photons assisted by the entanglement
We present a scheme to generate the frequency multiplexed entangled (FME)
single photons based on the entanglement between two species atomic mixture
ensemble. The write and reads fields driven according to a certain timing
sequence, the generation of FME single photons can be repeated until success is
achieved. The source might have significant applications in wavelength division
multiplexing quantum key distribution.Comment: 4 pages, 4 figures, submitted to PR
Optoelectronics of Inverted Type-I CdS/CdSe Core/Crown Quantum Ring
Inverted type-I heterostructure core/crown quantum rings (QRs) are
quantum-efficient luminophores, whose spectral characteristics are highly
tunable. Here, we study the optoelectronic properties of type-I core/crown
CdS/CdSe QRs in the zincblende phase - over contrasting lateral size and crown
width. For this we inspect their strain profiles, transition energies,
transition matrix elements, spatial charge densities, electronic bandstructure,
band-mixing probabilities, optical gain spectra, maximum optical gains and
differential optical gains. Our framework uses an effective-mass envelope
function theory based on the 8-band kp method employing the valence
force field model for calculating the atomic strain distributions. The gain
calculations are based on the density-matrix equation and take into
consideration the excitonic effects with intraband scattering. Variations in
the QR lateral size and relative widths of core and crown (ergo the
composition) affect their energy levels, band-mixing probabilities, optical
transition matrix elements, emission wavelengths/intensity, etc. The optical
gain of QRs is also strongly dimension and composition dependent with further
dependency on the injection carrier density causing band-filling effect. They
also affect the maximum and differential gain at varying dimensions and
compositions.Comment: Published in AIP Journal of Applied Physics (11 pages, 7 figures
Quantum Anomalous Hall Effect in Graphene Proximity Coupled to an Antiferromagnetic Insulator
We propose realizing the quantum anomalous Hall effect by proximity coupling
graphene to an antiferromagnetic insulator that provides both broken
time-reversal symmetry and spin-orbit coupling. We illustrate our idea by
performing ab initio calculations for graphene adsorbed on the (111) surface of
BiFeO3. In this case, we find that the proximity-induced exchange field in
graphene is about 70 meV, and that a topologically nontrivial band gap is
opened by Rashba spin-orbit coupling. The size of the gap depends on the
separation between the graphene and the thin film substrate, which can be tuned
experimentally by applying external pressure.Comment: 5pages, 5 figure
Social Friend Recommendation Based on Multiple Network Correlation
© 2015 IEEE. Friend recommendation is an important recommender application in social media. Major social websites such as Twitter and Facebook are all capable of recommending friends to individuals. However, most of these websites use simple friend recommendation algorithms such as similarity, popularity, or 'friend's friends are friends,' which are intuitive but consider few of the characteristics of the social network. In this paper we investigate the structure of social networks and develop an algorithm for network correlation-based social friend recommendation (NC-based SFR). To accomplish this goal, we correlate different 'social role' networks, find their relationships and make friend recommendations. NC-based SFR is characterized by two key components: 1) related networks are aligned by selecting important features from each network, and 2) the network structure should be maximally preserved before and after network alignment. After important feature selection has been made, we recommend friends based on these features. We conduct experiments on the Flickr network, which contains more than ten thousand nodes and over 30 thousand tags covering half a million photos, to show that the proposed algorithm recommends friends more precisely than reference methods
Effects of losses in the hybrid atom-light interferometer
Enhanced Raman scattering can be obtained by injecting a seeded light field
which is correlated with the initially prepared collective atomic excitation.
This Raman amplification process can be used to realize atom-light hybrid
interferometer. We numerically calculate the phase sensitivities and the
signal-to-noise ratios of this interferometer with the method of homodyne
detection and intensity detection, and give their differences between this two
methods. In the presence of loss of light field and atomic decoherence the
measure precision will be reduced which can be explained by the break of the
intermode decorrelation conditions of output modesComment: 9 pages, 7 figure
Entangling two distant nanocavities via a waveguide
In this paper, we investigate the generation of continuous variable
entanglement between two spatially-separate nanocavities mediated by a coupled
resonator optical waveguide in photonic crystals. By solving the exact dynamics
of the cavity system coupled to the waveguide, the entanglement and purity of
the two-mode cavity state are discussed in detail for the initially separated
squeezing inputs. It is found that the stable and pure entangled state of the
two distant nanocavities can be achieved with the requirement of only a weak
cavity-waveguide coupling when the cavities are resonant with the band center
of the waveguide. The strong couplings between the cavities and the waveguide
lead to the entanglement sudden death and sudden birth. When the frequencies of
the cavities lie outside the band of the waveguide, the waveguide-induced cross
frequency shift between the cavities can optimize the achievable entanglement.
It is also shown that the entanglement can be easily manipulated through the
changes of the cavity frequencies within the waveguide band.Comment: 8 pages, 8 figure
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