1,318 research outputs found
Spontaneous Interlayer Charge Transfer near the Magnetic Quantum Limit
Experiments reveal that a confined electron system with two equally-populated
layers at zero magnetic field can spontaneously break this symmetry through an
interlayer charge transfer near the magnetic quantum limit. New fractional
quantum Hall states at unusual total filling factors such as \nu = 11/15 (= 1/3
+ 2/5) stabilize as signatures that the system deforms itself, at substantial
electrostatic energy cost, in order to gain crucial correlation energy by
"locking in" separate incompressible liquid phases at unequal fillings in the
two layers (e.g., layered 1/3 and 2/5 states in the case of \nu = 11/15).Comment: 4 pages, 4 figures (1 color) included in text. Related papers at
http://www.ee.princeton.edu/~hari/papers.htm
Magnetic-Field-Induced Hybridization of Electron Subbands in a Coupled Double Quantum Well
We employ a magnetocapacitance technique to study the spectrum of the soft
two-subband (or double-layer) electron system in a parabolic quantum well with
a narrow tunnel barrier in the centre. In this system unbalanced by gate
depletion, at temperatures T\agt 30 mK we observe two sets of quantum
oscillations: one originates from the upper electron subband in the
closer-to-the-gate part of the well and the other indicates the existence of
common gaps in the spectrum at integer fillings. For the lowest filling factors
and , both the common gap presence down to the point of one- to
two-subband transition and their non-trivial magnetic field dependences point
to magnetic-field-induced hybridization of electron subbands.Comment: Major changes, added one more figure, the latest version to be
published in JETP Let
Quantum Hall effect in single wide quantum wells
We study the quantum Hall states in the lowest Landau level for a single wide
quantum well. Due to a separation of charges to opposite sides of the well, a
single wide well can be modelled as an effective two level system. We provide
numerical evidence of the existence of a phase transition from an
incompressible to a compressible state as the electron density is increased for
specific well width. Our numerical results show a critical electron density
which depends on well width, beyond which a transition incompressible double
layer quantum Hall state to a mono-layer compressible state occurs. We also
calculate the related phase boundary corresponding to destruction of the
collective mode energy gap. We show that the effective tunneling term and the
interlayer separation are both renormalised by the strong magnetic field. We
also exploite the local density functional techniques in the presence of strong
magnetic field at to calculate renormalized . The
numerical results shows good agreement between many-body calculations and local
density functional techniques in the presence of a strong magnetic field at
. we also discuss implications of this work on the
incompressible state observed in SWQW.Comment: 30 pages, 7 figures (figures are not included
Extrinsic Curvature Embedding Diagrams
Embedding diagrams have been used extensively to visualize the properties of
curved space in Relativity. We introduce a new kind of embedding diagram based
on the {\it extrinsic} curvature (instead of the intrinsic curvature). Such an
extrinsic curvature embedding diagram, when used together with the usual kind
of intrinsic curvature embedding diagram, carries the information of how a
surface is {\it embedded} in the higher dimensional curved space. Simple
examples are given to illustrate the idea.Comment: 22 pages, 4 figure
MACS: Multi-agent COTR system for Defense Contracting
The field of intelligent multi-agent systems has expanded rapidly in the recent past. Multi-agent architectures and systems are being investigated and continue to develop. To date, little has been accomplished in applying multi-agent systems to the defense acquisition domain. This paper describes the design, development, and related considerations of a multi-agent system in the area of procurement and contracting for the defense acquisition community
Shifting the quantum Hall plateau level in a double layer electron system
We study the plateaux of the integer quantum Hall resistance in a bilayer
electron system in tilted magnetic fields. In a narrow range of tilt angles and
at certain magnetic fields, the plateau level deviates appreciably from the
quantized value with no dissipative transport emerging. A qualitative account
of the effect is given in terms of decoupling of the edge states corresponding
to different electron layers/Landau levels.Comment: 3 pages, 3 figures include
Late Time Tail of Wave Propagation on Curved Spacetime
The late time behavior of waves propagating on a general curved spacetime is
studied. The late time tail is not necessarily an inverse power of time. Our
work extends, places in context, and provides understanding for the known
results for the Schwarzschild spacetime. Analytic and numerical results are in
excellent agreement.Comment: 11 pages, WUGRAV-94-1
The Collision of Two Black Holes
We study the head-on collision of two equal mass, nonrotating black holes. We
consider a range of cases from holes surrounded by a common horizon to holes
initially separated by about , where is the mass of each hole. We
determine the waveforms and energies radiated for both the and
waves resulting from the collision. In all cases studied the normal
modes of the final black hole dominate the spectrum. We also estimate
analytically the total gravitational radiation emitted, taking into account the
tidal heating of horizons using the membrane paradigm, and other effects. For
the first time we are able to compare analytic calculations, black hole
perturbation theory, and strong field, nonlinear numerical calculations for
this problem, and we find excellent agreement.Comment: 14 pages, 93-
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