324 research outputs found
Quantum treatment of neutrino in background matter
Motivated by the need of elaboration of the quantum theory of the spin light
of neutrino in matter (), we have studied in more detail the exact
solutions of the Dirac equation for neutrinos moving in the background matter.
These exact neutrino wavefunctions form a basis for a rather powerful method of
investigation of different neutrino processes in matter, which is similar to
the Furry representation of quantum electrodynamics in external fields. Within
this method we also derive the corresponding Dirac equation for an electron
moving in matter and consider the electromagnetic radiation ("spin light of
electron in matter", ) that can be emitted by the electron in this case.Comment: 10 pages, in: Proceedings of QFEXT'05 (The Seventh Workshop on
Quantum Field Theory under the Influence of External Conditions, IEEC, CSIC
and University of Barcelona, Barcelona, Catalonia, Spain, 5-9 September
2005.), ed. by Emilio Elizalde and Sergei Odintsov; published in Journal of
Physics
Few-electron quantum dots in III-V ternary alloys: role of fluctuations
We study experimentally the electron transport properties of gated quantum
dots formed in InGaAs/InP and InAsP/InP quantum well structures grown by
chemical-beam epitaxy. For the case of the InGaAs quantum well, quantum dots
form directly underneath narrow gate electrodes due to potential fluctuations.
We measure the Coulomb-blockade diamonds in the few-electron regime of a single
quantum dot and observe photon-assisted tunneling peaks under microwave
irradiation. A singlet-triplet transition at high magnetic field and
Coulomb-blockade effects in the quantum Hall regime are also observed. For the
InAsP quantum well, an incidental triple quantum dot forms also due to
potential fluctuations within a single dot layout. Tunable quadruple points are
observed via transport measurements.Comment: 3.3 pages, 3 figures. Added two new subfigures, new references, and
improved the tex
Microwave magnetoplasmon absorption by a 2DEG stripe
Microwave absorption by a high mobility 2DEG has been investigated
experimentally using sensitive Electron Paramagnetic Resonance cavity
technique. It is found that MW absorption spectra are chiefly governed by
confined magnetoplasmon excitations in a 2DEG stripe. Spectra of the 2D
magnetoplasmons are studied as a function of magnetic field, MW frequency and
carrier density. The electron concentration is tuned by illumination and
monitored using optical photoluminescence technique.Comment: to be published in International Journal of Modern Physics
Coherent Transport Through a Quadruple Point in a Few Electron Triple Dot
A few electron double electrostatic lateral quantum dot can be transformed
into a few electron triple quantum dot by applying a different combination of
gate voltages. Quadruple points have been achieved at which all three dots are
simultaneously on resonance. At these special points in the stability diagram
four occupation configurations are possible. Both charge detection and
transport experiments have been performed on this device. In this short paper
we present data and confirm that transport is coherent by observing a Pi phase
shift in magneto-conductance oscillations as one passes through the quadruple
point.Comment: To be published in ICPS Conf. Proceedings 200
A Tuneable Few Electron Triple Quantum Dot
In this paper we report on a tuneable few electron lateral triple quantum dot
design. The quantum dot potentials are arranged in series. The device is aimed
at studies of triple quantum dot properties where knowing the exact number of
electrons is important as well as quantum information applications involving
electron spin qubits. We demonstrate tuning strategies for achieving required
resonant conditions such as quadruple points where all three quantum dots are
on resonance. We find that in such a device resonant conditions at specific
configurations are accompanied by novel charge transfer behaviour.Comment: 11 pages, 4 figure
Covariant Treatment of Neutrino Spin (Flavour) Conversion in Matter under the Influence of Electromagnetic Fields
Within the recently proposed Lorentz invariant formalism for description of
neutrino spin evolution in presence of an arbitrary electromagnetic fields
effects of matter motion and polarization are considered.Comment: Extended version of contribution to "Particle Physics on Boundary of
Millenniums" (Proceedings of the 9th Lomonosov Conference on Elementary
Particle Physics, World Scientific, Singapure
Spin light of electron in dense matter
We derive the modified Dirac equation for an electron undergos an influence
of the standard model interaction with the nuclear matter. The exact solutions
for this equation and the electron energy spectrum in matter are obtained. This
establishes a rather powerful method for investigation of different processes
that can appear when electrons propagate in background matter. On this basis we
study in detail the spin light of electron in nuclear matter, a new type of
electromagnetic radiation which can be emitted by an electron moving in dense
matter.Comment: 11 pages in LaTex, 4 figures, typos correcte
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