33 research outputs found
General Localization Lengths for Two Interacting Particles in a Disordered Chain
The propagation of an interacting particle pair in a disordered chain is
characterized by a set of localization lengths which we define. The
localization lengths are computed by a new decimation algorithm and provide a
more comprehensive picture of the two-particle propagation. We find that the
interaction delocalizes predominantly the center-of-mass motion of the pair and
use our approach to propose a consistent interpretation of the discrepancies
between previous numerical results.Comment: 4 pages, 2 epsi figure
Scaling near Quantum Chaos Border in Interacting Fermi Systems
The emergence of quantum chaos for interacting Fermi systems is investigated
by numerical calculation of the level spacing distribution as function
of interaction strength and the excitation energy above the
Fermi level. As increases, undergoes a transition from Poissonian
(nonchaotic) to Wigner-Dyson (chaotic) statistics and the transition is
described by a single scaling parameter given by , where is a constant. While the exponent ,
which determines the global change of the chaos border, is indecisive within a
broad range of , finite value of , which comes from the
increase of the Fock space size with , suggests that the transition
becomes sharp as increases.Comment: 4 pages, 4 figures, to appear in Phys. Rev. E (Rapid Communication
Low energy transition in spectral statistics of 2D interactingfermions
We study the level spacing statistics and eigenstate properties of
spinless fermions with Coulomb interaction on a two dimensional lattice at
constant filling factor and various disorder strength. In the limit of large
lattice size, undergoes a transition from the Poisson to the
Wigner-Dyson distribution at a critical total energy independent of the number
of fermions. This implies the emergence of quantum ergodicity induced by
interaction and delocalization in the Hilbert space at zero temperature.Comment: revtex, 5 pages, 4 figures; new data for eigenfunctions are adde
Nanovesicles derived from iron oxide nanoparticles-incorporated mesenchymal stem cells for cardiac repair
Because of poor engraftment and safety concerns regarding mesenchymal stem cell (MSC) therapy, MSC-derived exosomes have emerged as an alternative cell-free therapy for myocardial infarction (MI). However, the diffusion of exosomes out of the infarcted heart following injection and the low productivity limit the potential of clinical applications. Here, we developed exosome-mimetic extracellular nanovesicles (NVs) derived from iron oxide nanoparticles (IONPs)-incorporated MSCs (IONP-MSCs). The retention of injected IONP-MSC-derived NVs (IONP-NVs) within the infarcted heart was markedly augmented by magnetic guidance. Furthermore, IONPs significantly increased the levels of therapeutic molecules in IONP-MSCs and IONP-NVs, which can reduce the concern of low exosome productivity. The injection of IONP-NVs into the infarcted heart and magnetic guidance induced an early shift from the inflammation phase to the reparative phase, reduced apoptosis and fibrosis, and enhanced angiogenesis and cardiac function recovery. This approach can enhance the therapeutic potency of an MSC-derived NV therapy.
Quantum computing of quantum chaos and imperfection effects
We study numerically the imperfection effects in the quantum computing of the
kicked rotator model in the regime of quantum chaos. It is shown that there are
two types of physical characteristics: for one of them the quantum computation
errors grow exponentially with the number of qubits in the computer while for
the other the growth is polynomial. Certain similarity between classical and
quantum computing errors is also discussed.Comment: revtex, 4 pages, 4 figure
Spin relaxation of conduction electrons in bulk III-V semiconductors
Spin relaxation time of conduction electrons through the Elliot-Yafet,
D'yakonov-Perel and Bir-Aronov-Pikus mechanisms is calculated theoretically for
bulk GaAs, GaSb, InAs and InSb of both - and -type. Relative importance
of each spin relaxation mechanism is compared and the diagrams showing the
dominant mechanism are constructed as a function of temperature and impurity
concentrations. Our approach is based upon theoretical calculation of the
momentum relaxation rate and allows understanding of the interplay between
various factors affecting the spin relaxation over a broad range of temperature
and impurity concentration.Comment: an error in earlier version correcte