11,219 research outputs found
Optical Signatures of Spin-Orbit Interaction Effects in a Parabolic Quantum Dot
We demonstrate here that the dipole-allowed optical absorption spectrum of a
parabolic quantum dot subjected to an external magnetic field reflects the
inter-electron interaction effects when the spin-orbit interaction is also
taken into account. We have investigated the energy spectra and the
dipole-allowed transition energies for up to four interacting electrons
parabolically confined, and have uncovered several novel features in those
spectra that are solely due to the SO interaction.Comment: 4 pages, 3 figure
Topological entropy of realistic quantum Hall wave functions
The entanglement entropy of the incompressible states of a realistic quantum
Hall system are studied by direct diagonalization. The subdominant term to the
area law, the topological entanglement entropy, which is believed to carry
information about topologic order in the ground state, was extracted for
filling factors 1/3, 1/5 and 5/2. The results for 1/3 and 1/5 are consistent
with the topological entanglement entropy for the Laughlin wave function. The
5/2 state exhibits a topological entanglement entropy consistent with the
Moore-Read wave function.Comment: 6 pages, 6 figures; improved computations and graphics; added
reference
Temperature dependence of spin polarizations at higher Landau Levels
We report our results on temperature dependence of spin polarizations at
in the lowest as well as in the next higher Landau level that compare
well with recent experimental results. At , except having a much smaller
magnitude the behavior of spin polarization is not much influenced by higher
Landau levels. In sharp contrast, for filling factor we predict
that unlike the case of the system remains fully spin polarized
even at vanishingly small Zeeman energies.Comment: 4 pages, REVTEX, and 3 .ps files, To be published in Physical Review
Letter
Composite Fermions in Quantum Dots
We demonstrate the formation of composite fermions in two-dimensional quantum
dots under high magnetic fields. The composite fermion interpretation provides
a simple way to understand several qualitative and quantitative features of the
numerical results obtained earlier in exact diagonalization studies. In
particular, the ground states are recognized as compactly filled quasi-Landau
levels of composite fermions.Comment: Revtex. Postscript files of figures are appended the tex
Energy levels and magneto-optical transitions in parabolic quantum dots with spin-orbit coupling
We report on the electronic properties of few interacting electrons confined
in a parabolic quantum dot based on a theoretical approach developed to
investigate the influence of Bychkov-Rashba spin-orbit (SO) interaction on such
a system. We note that the spin-orbit coupling profoundly influences the energy
spectrum of interacting electrons in a quantum dot. Here we present accurate
results for the energy levels and optical-absorption spectra for parabolic
quantum dots containing upto four interacting electrons, in the presence of
spin-orbit coupling and under the influence of an externally applied,
perpendicular magnetic field. We have described in detail about a very accurate
numerical scheme to evaluate these quantities. We have evaluated the effects of
SO coupling on the Fock-Darwin spectra for quantum dots made out of three
different semiconductor systems, InAs, InSb, and GaAs.Comment: expanded version of cond-mat/0501642 to be published in Phys. Rev.
Let
Nonperturbative comparison of clover and highly improved staggered quarks in lattice QCD and the properties of the Ď• meson
We compare correlators for pseudoscalar and vector mesons made from valence strange quarks using the
clover quark and highly improved staggered quark (HISQ) formalisms in full lattice QCD. We use fully
nonperturbative methods to normalize vector and axial vector current operators made from HISQ quarks,
clover quarks and from combining HISQ and clover fields. This allows us to test expectations for the
renormalization factors based on perturbative QCD, with implications for the error budget of lattice QCD
calculations of the matrix elements of clover-staggered b-light weak currents, as well as further HISQ
calculations of the hadronic vacuum polarization.We also compare the approach to the (same) continuum limit
in clover and HISQ formalisms for the mass and decay constant of the Ď• meson. Our final results for these
parameters, using single-meson correlators and allowing an uncertainty for the neglect of quark-line
disconnected diagrams are: Mϕ ¼ 1.023ð6Þ GeV and fϕ ¼ 0.238ð3Þ GeV in good agreement with experiment.
The results come from calculations in the HISQ formalism using gluon fields that include the effect of u,
d, s and c quarks in the sea with three lattice spacing values and mu=d values going down to the physical point
Intersubband magnetophonon resonances in quantum cascade structures
We report on our magnetotransport measurements of GaAs/GaAlAs quantum cascade
structures in a magnetic field of up to 62 T. We observe novel quantum
oscillations in tunneling current that are periodic in reciprocal magnetic
field. We explain these oscillations as intersubband magnetophonon resonance
due to electron relaxation by emission of either single optical or acoustic
phonons. Our work also provides a non-optical in situ measurement of
intersubband separations in quantum cascade structures.Comment: 5 pages, 4 figure
A Fermi Fluid Description of the Half-Filled Landau Level
We present a many-body approach to calculate the ground state properties of a
system of electrons in a half-filled Landau level. Our starting point is a
simplified version of the recently proposed trial wave function where one
includes the antisymmetrization operator to the bosonic Laughlin state. Using
the classical plasma analogy, we calculate the pair-correlation function, the
static structure function and the ground state energy in the thermodynamic
limit. These results are in good agreement with the expected behavior at
.Comment: 4 pages, REVTEX, and 4 .ps file
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