6 research outputs found
Engineering directed excitonic energy transfer
We provide an intuitive platform for engineering exciton transfer dynamics.
We show that careful consideration of the spectral density, which describes the
system-bath interaction, leads to opportunities to engineer the transfer of an
exciton. Since excitons in nanostructures are proposed for use in quantum
information processing and artificial photosynthetic designs, our approach
paves the way for engineering a wide range of desired exciton dynamics. We
carefully describe the validity of the model and use experimentally relevant
material parameters to show counter-intuitive examples of a directed exciton
transfer in a linear chain of quantum dots
Spin current injection by intersubband transitions in quantum wells
We show that a pure spin current can be injected in quantum wells by the
absorption of linearly polarized infrared radiation, leading to transitions
between subbands. The magnitude and the direction of the spin current depend on
the Dresselhaus and Rashba spin-orbit coupling constants and light frequency
and, therefore, can be manipulated by changing the light frequency and/or
applying an external bias across the quantum well. The injected spin current
should be observable either as a voltage generated via the anomalous spin-Hall
effect, or by spatially resolved pump-probe optical spectroscopy.Comment: minor changes, short version publishe
Quantum states and linear response in dc and electromagnetic fields for charge current and spin polarization of electrons at Bi/Si interface with giant spin-orbit coupling
An expansion of the nearly free-electron model constructed by Frantzeskakis,
Pons and Grioni [Phys. Rev. B {\bf 82}, 085440 (2010)] describing quantum
states at Bi/Si(111) interface with giant spin-orbit coupling is developed and
applied for the band structure and spin polarization calculation, as well as
for the linear response analysis for charge current and induced spin caused by
dc field and by electromagnetic radiation. It is found that the large
spin-orbit coupling in this system may allow resolving the spin-dependent
properties even at room temperature and at realistic collision rate. The
geometry of the atomic lattice combined with spin-orbit coupling leads to an
anisotropic response both for current and spin components related to the
orientation of the external field. The in-plane dc electric field produces only
the in-plane components of spin in the sample while both the in-plane and
out-of-plane spin components can be excited by normally propagating
electromagnetic wave with different polarizations.Comment: 10 pages, 9 figure
Coherent control of electron propagation and capture in semiconductor heterostructures
We theoretically study the use of quantum interference to coherently control the transverse direction in which carriers are optically injected in a semiconductor heterostructure, and the subsequent transport and capture of these carriers. We consider a structure consisting of three quantum wells, where carriers can be ejected from the middle one in a given direction by coherently controlled optical pulse excitations. After traveling through the barrier, electrons are slowed down by space-charge effects, and can be captured in the side wells by emitting a phonon. If the side wells are different, the coherent control of the injection can be monitored optically. We propose a design of a AlGaAs heterostructure for a possible experimental realization of the effects considered in this paper