114 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
Exciton-Polariton Quantum Gates Based on Continuous Variables
We propose a continuous variable analog of quantum controlled-NOT gates based
on a system of exciton-polaritons in semiconductor microcavities. This can be
realized by the engineering of parametric interaction between control and
target polariton modes, which can be varied in time. As an explicit setup we
use a system of dipolaritons, which allows for enhancement of parametric
interaction by auxiliary classical fields and scalable multigate system
realization. The calculated fidelity is shown to exceed 99% for realistic
system parameters.Comment: 6 pages, 3 figures + 6 pages, 2 figures supplemental materia
Floquet control of dipolaritons in quantum wells
We developed the theory of dipolaritons in semiconductor quantum wells
irradiated by an off-resonant electromagnetic wave (dressing field). Solving
the Floquet problem for the dressed dipolaritons, we demonstrated that the
field drastically modifies all dipolaritonic properties. In particular, the
dressing field strongly effects on terahertz emission from the considered
system. The described effect paves the way for optical control of prospective
dipolariton-based terahertz devices.Comment: Published versio
Structure of surface electronic states in strained mercury telluride
We present the theory describing the various surface electronic states arisen
from the mixing of conduction and valence bands in a strained mercury telluride
(HgTe) bulk material. We demonstrate that the strain-induced band gap in the
Brillouin zone center of HgTe results in the surface states of two different
kinds. Surface states of the first kind exist in the small region of electron
wave vectors near the center of the Brillouin zone and have the Dirac linear
electron dispersion characteristic for topological states. The surface states
of the second kind exist only far from the center of the Brillouin zone and
have the parabolic dispersion for large wave vectors. The structure of these
surface electronic states is studied both analytically and numerically in the
broad range of their parameters, aiming to develop its systematic understanding
for the relevant model Hamiltonian. The results bring attention to the rich
surface physics relevant for topological systems.Comment: Published version. arXiv admin note: text overlap with
arXiv:1903.0457
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
Quantum inverse iteration algorithm for programmable quantum simulators
This is the final version. Available on open access from Nature Research via the DOI in this recordData availability:
The author declares that the data supporting the findings of this study are available within the paper and its supplementary information file.We propose a quantum inverse iteration algorithm which can be used to estimate the ground state properties of a programmable quantum device. The method relies on the inverse power iteration technique, where the sequential application of the Hamiltonian inverse to an initial state prepares an approximate groundstate. To apply the inverse Hamiltonian operation, we write it as a sum of unitary evolution operators using the Fourier approximation approach. This allows to reformulate the protocol as separate measurements for the overlap of initial and propagated wavefunction. The algorithm thus crucially depends on the ability to run Hamiltonian dynamics with an available quantum device. We benchmark the performance using paradigmatic examples of quantum chemistry, corresponding to molecular hydrogen and beryllium hydride. Finally, we show its use for studying the ground state properties of relevant material science models which can be simulated with existing devices, considering an example of the Bose-Hubbard atomic simulator
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
Spin-orbit coupled cold exciton condensates
We analyze theoretically the dynamics of degenerate condensate of cold
indirect excitons. We account for both linear spin dependent terms arising from
spin-orbit interaction of Rashba and Dresselhaus types and non-linear terms
transforming a pair of bright excitons into a pair of dark ones. We show that
both terms should lead to the qualitative changes in the dynamics of cold
exciton droplets in the real space and time.Comment: 14 pages, 7 figure
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