4 research outputs found
Correlated time-dependent transport through a 2D quantum structure
We use a generalized master equation (GME) to describe the nonequilibrium
magnetotransport of interacting electrons through a broad finite quantum wire
with an embedded ring structure. The finite quantum wire is weakly coupled to
two broad leads acting as reservoirs of electrons. The mutual Coulomb
interaction of the electrons is described using a configuration interaction
method for the many-electron states of the central system. We report some
non-trivial interaction effects both at the level of time-dependent filling of
states and on the time-dependent transport. We find that the Coulomb
interaction in this non-trivial geometry can enhance the correlation of
electronic states in the system and facilitate it's charging in certain
circumstances in the weak coupling limit appropriate for the GME. In addition,
we find oscillations in the current in the leads due to the correlations
oscillations caused by the switched-on lead- system coupling. The oscillations
are influenced and can be enhanced by the external magnetic field and the
Coulomb interaction.Comment: RevTeX (pdf-LaTeX), 10 pages with 15 included jpg figure
Pauli principle and chaos in a magnetized disk
We present results of a detailed quantum mechanical study of a gas of
noninteracting electrons confined to a circular boundary and subject to
homogeneous dc plus ac magnetic fields , with
). We earlier found a one-particle {\it classical}
phase diagram of the (scaled) Larmor frequency
{\rm vs} that
separates regular from chaotic regimes. We also showed that the quantum
spectrum statistics changed from Poisson to Gaussian orthogonal ensembles in
the transition from classically integrable to chaotic dynamics. Here we find
that, as a function of and , there are clear
quantum signatures in the magnetic response, when going from the
single-particle classically regular to chaotic regimes. In the quasi-integrable
regime the magnetization non-monotonically oscillates between diamagnetic and
paramagnetic as a function of . We quantitatively understand this behavior
from a perturbation theory analysis. In the chaotic regime, however, we find
that the magnetization oscillates as a function of but it is {\it always}
diamagnetic. Equivalent results are also presented for the orbital currents. We
also find that the time-averaged energy grows like in the
quasi-integrable regime but changes to a linear dependence in the chaotic
regime. In contrast, the results with Bose statistics are akin to the
single-particle case and thus different from the fermionic case. We also give
an estimate of possible experimental parameters were our results may be seen in
semiconductor quantum dot billiards.Comment: 22 pages, 7 GIF figures, Phys. Rev. E. (1999