327 research outputs found
Intersubband polaritons with spin-orbit interaction
We investigate intersubband polaritons formed in the asymmetric quantum well
(AQW) embedded into the semiconductor microcavity and study the effects of
spin-orbit interaction (SOI) acting on intersubband excitations. The spin-orbit
interaction of Rashba and Dresselhaus type remove the spin degeneracy of
electrons with finite value of in-plane momentum and allow four types of
intersubband excitations. While optical spin-flip transitions are suppressed,
the spectrum of elementary excitations shows the appearance of upper, lower and
middle polaritonic branches based on spin-conserving transitions. The
accounting of finite photon momentum leads to non-zero average spin projection
of electronic ensemble in the first excited subband under cw excitation for
both isotropic (Rashba) and anisotropic (Rashba and Dresselhaus) SOI. We
predict the possibility of spin current generation in the considered systems
with long coherence length.Comment: 9 pages, 8 figure
THz laser based on dipolaritons
We develop the microscopic theory of a terahertz (THz) laser based on the
effects of resonant tunneling in a double quantum well heterostructure embedded
in both optical and THz cavities. In the strong coupling regime the system
hosts dipolaritons, hybrid quasiparticles formed by the direct exciton,
indirect exciton and optical photon, which possess large dipole moments in the
growth direction. Their radiative coupling to the mode of a THz cavity combined
with strong non-linearities provided by exciton-exciton interactions allows for
stable emission of THz radiation in the regime of the continuous optical
excitation. The optimal parameters for maximizing the THz signal output power
are analyzed.Comment: 8 pages, 7 figure
Bistability phenomena in one-dimensional polariton wires
We investigate the phenomena of bistability and domain wall propagation in
polaritonic systems with dissipation provided by the interaction with
incoherent phonon bath. The results on the temperature dependence of the
polariton bistability behavior and polariton neuron switching are presented.Comment: 6 pages + 4 figures. Continuation of the work published in Phys. Rev.
B 83, 165316 (2011
Density-matrix approach for an interacting polariton system
Using the Lindblad approach we develop a general formalism for theoretical
description of a spatially inhomogeneous bosonic system with dissipation
provided by the interaction of bosons with a phonon bath. We apply our results
to model the dynamics of an interacting one-dimensional polariton system in
real space and time, analyzing in detail the role of polariton-polariton and
polariton-phonon interactions.Comment: 7 pages + 3 figures. arXiv admin note: text overlap with
arXiv:1103.1336 by other author
Superradiant terahertz emission by dipolaritons
Dipolaritons are mixed light-matter quasiparticles formed in double quantum
wells embedded in microcavities. Due to resonant coupling between direct and
indirect excitons via electronic tunnelling, dipolaritons possess large dipole
moments. Resonant excitation of the cavity mode by a short pulse of light
induces oscillations of the indirect exciton density with a characteristic
frequency of Rabi flopping. This results in oscillations of classical Hertz
dipoles array which generate supperradiant emission on a terahertz (THz)
frequency. Resulting THz signal may be enhanced using the supplementary THz
cavity in the weak coupling regime.Comment: 5+10 pages, 3+5 figures; close to printed version, to appear in Phys.
Rev. Let
Exciton-exciton interaction in transition-metal dichalcogenide monolayers
We study theoretically the Coulomb interaction between excitons in transition
metal dichalcogenide (TMD) monolayers. We calculate direct and exchange
interaction for both ground and excited states of excitons. The screening of
the Coulomb interaction, specific to monolayer structures, leads to the unique
behavior of the exciton-exciton scattering for excited states, characterized by
the non-monotonic dependence of the interaction as function of the transferred
momentum. We find that the nontrivial screening enables the description of TMD
exciton interaction strength by approximate formula which includes exciton
binding parameters. The influence of screening and dielectric environment on
the exciton-exciton interaction was studied, showing qualitatively different
behavior for ground state and excited states of excitons. Furthermore, we
consider exciton-electron interaction, which for the excited states is governed
by the dominant attractive contribution of the exchange component, which
increases with the excitation number. The results provide a quantitative
description of the exciton-exciton and exciton-electron scattering in
transition metal dichalcogenides, and are of interest for the design of
perspective nonlinear optical devices based on TMD monolayers.Comment: 10 pages, 6 figure
Functional renormalization group approach to the singlet-triplet transition in quantum dots
We present a functional renormalization group approach to the zero bias
transport properties of a quantum dot with two different orbitals and in
presence of Hund's coupling. Tuning the energy separation of the orbital
states, the quantum dot can be driven through a singlet-triplet transition. Our
approach, based on the approach by Karrasch {\em et al} which we apply to
spin-dependent interactions, recovers the key characteristics of the quantum
dot transport properties with very little numerical effort. We present results
on the conductance in the vicinity of the transition and compare our results
both with previous numerical renormalization group results and with predictions
of the perturbative renormalization group.Comment: 15 pages, 9 figure
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