219 research outputs found
Angle Dependence of Photonic Enhancement of Magneto-Optical Kerr Effect in DMS Layers
We investigate theoretically an angle dependence of enhancement of polar
magneto-optical Kerr effect (MOKE) obtained thanks to a deposition of a
paramagnetic Diluted Magnetic Semiconductor (DMS) layer on one-dimensional
photonic crystal layer. Our transfer matrix method based calculations conducted
for TE and TM polarizations of the incident light predict up to an order of
magnitude stronger MOKE for a (Ga,Fe)N DMS layer when implementing the proposed
design. The maximum enhancement for TE and TM polarization occurs for the light
incidence at the normal and at the Brewster angle, respectively. This indicates
a possibility of tuning of the MOKE enhancement by adjustment of the
polarization and the incidence angle of the light.Comment: 6 figure
Event--related desynchronization in diffusively coupled oscillator models
We seek explanation for the neurophysiological phenomenon of event related
desynchronization (ERD) by using models of diffusively coupled nonlinear
oscillators. We demonstrate that when the strength of the event is sufficient,
ERD is found to emerge and the accomplishment of a behavioral/functional task
is determined by the nature of the desynchronized state. We illustrate the
phenomenon for the case of limit cycle and chaotic systems. We numerically
demonstrate the occurrence of ERD and provide analytical explanation. We also
discuss possible applications of the observed phenomenon in real physical
systems other than the brain.Comment: Accepted in Physical Review Letter
Controlled light-matter coupling for a single quantum dot embedded in a pillar microcavity using far-field optical lithography
Using far field optical lithography, a single quantum dot is positioned
within a pillar microcavity with a 50 nm accuracy. The lithography is performed
in-situ at 10 K while measuring the quantum dot emission. Deterministic
spectral and spatial matching of the cavity-dot system is achieved in a single
step process and evidenced by the observation of strong Purcell effect.
Deterministic coupling of two quantum dots to the same optical mode is
achieved, a milestone for quantum computing.Comment: Modified version: new title, additional experimental data in figure
Influence of s,p-d and s-p exchange couplings on exciton splitting in (Zn,Mn)O
This work presents results of near-band gap magnetooptical studies on
(Zn,Mn)O epitaxial layers. We observe excitonic transitions in reflectivity and
photoluminescence, that shift towards higher energies when the Mn concentration
increases and split nonlinearly under the magnetic field. Excitonic shifts are
determined by the s,p-d exchange coupling to magnetic ions, by the
electron-hole s-p exchange, and the spin-orbit interactions. A quantitative
description of the magnetoreflectivity findings indicates that the free
excitons A and B are associated with the Gamma_7 and Gamma_9 valence bands,
respectively, the order reversed as compared to wurtzite GaN. Furthermore, our
results show that the magnitude of the giant exciton splittings, specific to
dilute magnetic semiconductors, is unusual: the magnetoreflectivity data is
described by an effective exchange energy N_0(beta-alpha)=+0.2+/-0.1 eV, what
points to small and positive N_0 beta. It is shown that both the increase of
the gap with x and the small positive value of the exchange energy N_0 beta
corroborate recent theory describing the exchange splitting of the valence band
in a non-perturbative way, suitable for the case of a strong p-d hybridization.Comment: 8 pages, 8 figure
Effect of pure dephasing on the Jaynes-Cummings nonlinearities
We study the effect of pure dephasing on the strong-coupling between a
quantum dot and the single mode of a microcavity in the nonlinear regime. We
show that the photoluminescence spectrum of the system has a robust tendency to
display triplet structures, instead of the expected Jaynes-Cummings pairs of
doublets at the incommensurate frequencies for
integer . We show that current experimental works may already manifest
signatures of single photon nonlinearities.Comment: v2: 4 Pages,3 figures. New figure 2 and some changes in the text. New
author adde
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