1,193 research outputs found
Quantum Dynamics of Mesoscopic Driven Duffing Oscillators
We investigate the nonlinear dynamics of a mesoscopic driven Duffing
oscillator in a quantum regime. In terms of Wigner function, we identify the
nature of state near the bifurcation point, and analyze the transient process
which reveals two distinct stages of quenching and escape. The rate process in
the escape stage allows us to extract the transition rate, which displays
perfect scaling behavior with the driving distance to the bifurcation point. We
numerically determine the scaling exponent, compare it with existing result,
and propose open questions to be resolved.Comment: 4 pages, 4 figures; revised version accepted for publication in EP
Superfluidity and effective mass of magnetoexcitons in topological insulator bilayers: Effect of inter-Landau-level Coulomb interaction
The effective mass and superfluidity-normal phase transition temperature of
magnetoexcitons in topological insulator bilayers are theoretically
investigated. The intra-Landau-level Coulomb interaction is treated
perturbatively, from which the effective magnetoexciton mass is analytically
discussed. The inclusion of inter-Landau-level Coulomb interaction by more
exact numerical diagonalization of the Hamiltonian brings out important
modifications to magnetoexciton properties, which are specially characterized
by prominent reduction in the magnetoexciton effective mass and promotion in
the superfluidity-normal phase transition temperature at a wide range of
external parameters.Comment: 5.6 EPL pages, 4 figure
Fractional quantum Hall effect of topological surface states under a strong tilted magnetic field
The fractional quantum Hall effect (FQHE) of topological surface-state
particles under a tilted strong magnetic field is theoretically studied by
using the exact diagonalization method. The Haldane's pseudopotentials for the
Coulomb interaction are analytically obtained. The results show that by
increasing the in-plane component of the tilted magnetic field, the FQHE state
at =0 Landau level (LL) becomes more stable, while the stabilities of
= LLs become weaker. Moreover, we find that the excitation gaps of the
FQHE states increase as the tilt angle is increased.Comment: 4.2 pages, 4 figure
Quantum Corrals and Quantum Mirages on the Surface of a Topological Insulator
We study quantum corrals on the surface of a topological insulator (TI).
Different resonance states induced by nonmagnetic (NM), antiferromagnetic
(AFM), and ferromagnetic (FM) corrals are found. Intriguingly, the spin is
clearly energy-resolved in a FM corral, which can be effectively used to
operate surface carrier spins of TI. We also show that an observable quantum
mirage of a magnetic impurity can be projected from the occupied into the empty
focus of a FM elliptic corral, while in NM and AFM corrals the mirage signal
becomes negligibly weak. In addition, the modulation of the interaction between
two magnetic impurities in the quantum corrals is demonstrated. These prominent
effects may be measured by spin-polarized STM experiments.Comment: 5 PRB pages, 4 figure
Multiple-trait quantitative trait locus mapping with incomplete phenotypic data
<p>Abstract</p> <p>Background</p> <p>Conventional multiple-trait quantitative trait locus (QTL) mapping methods must discard cases (individuals) with incomplete phenotypic data, thereby sacrificing other phenotypic and genotypic information contained in the discarded cases. Under standard assumptions about the missing-data mechanism, it is possible to exploit these cases.</p> <p>Results</p> <p>We present an expectation-maximization (EM) algorithm, derived for recombinant inbred and F<sub>2 </sub>genetic models but extensible to any mating design, that supports conventional hypothesis tests for QTL main effect, pleiotropy, and QTL-by-environment interaction in multiple-trait analyses with missing phenotypic data. We evaluate its performance by simulations and illustrate with a real-data example.</p> <p>Conclusion</p> <p>The EM method affords improved QTL detection power and precision of QTL location and effect estimation in comparison with case deletion or imputation methods. It may be incorporated into any least-squares or likelihood-maximization QTL-mapping approach.</p
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