384 research outputs found
Scattering of Bunched Fractionally Charged Quasiparticles
The charge of fractionally charged quasiparticles, proposed by Laughlin to
explain the fractional quantum Hall effect (FQHE), was recently verified by
measurements. Charge q=e/3 and e/5 (e is the electron charge), at filling
factors nu=1/3 and 2/5, respectively, were measured. Here we report the
unexpected bunching of fractional charges, induced by an extremely weak
backscattering potential at exceptionally low electron temperatures (T<10 mK) -
deduced from shot noise measurements. Backscattered charges q=nu e,
specifically, q=e/3, q=2e/5, and q<3e/7, in the respective filling factors,
were measured. For the same settings but at an only slightly higher electron
temperature, the measured backscattered charges were q=e/3, q=e/5, and q=e/7.
In other words, bunching of backscattered quasiparticles is taking place at
sufficiently low temperatures. Moreover, the backscattered current exhibited
distinct temperature dependence that was correlated to the backscattered charge
and the filling factor. This observation suggests the existence of 'low' and
'high' temperature backscattering states, each with its characteristic charge
and characteristic energy.Comment: 4 pages, 3 figure
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Design of bent photonic crystal fiber supporting a single polarization
In this work, it is shown that the differential loss between the TE- and TM-polarized fundamental modes in a highly birefringent photonic crystal fiber (PCF) can be enhanced by bending the fiber. As a result, a design approach for single-mode single-polarization operation has been developed and is discussed. A rigorous full-vectorial H-field-based finite element approach, which includes the conformal transformation and the perfectly matched layer, is used to determine the single-polarization properties of such a highly birefringent PCF by exploiting its differential bending losses
Shot noise as a tool to probe an electron energy distribution
We discuss the possibility to employ the shot-noise measurements for the
analysis of the energy resolved ballistic currents. Coulomb interactions play
an essential role in this technique, since they lead to the
shot-noise-suppression level which depends on the details of the energy
profile.Comment: 7 pages, 2 figs; contribution to the Proceedings of EP2DS-14, Prague,
2001; to appear in Physica
Phase Evolution in a Kondo Correlated System
The coherence and phase evolution of electrons in a mesoscopic system in the
Kondo correlated regime were studied. The Kondo effect, in turn, is one of the
most fundamental many-body effects where a localized spin interacts with
conduction electrons in a conductor. Results were obtained by embedding a
quantum dot (QD) in a double path electronic interferometer and measuring
interference of electron waves. The Phase was found to evolve in a range twice
as large as the theoretically predicted one. Moreover, the phase proved to be
highly sensitive to the onset of Kondo correlation, thus serving as a new
fingerprint of the Kondo effect.Comment: 4 pages, 4 figures. typos corrected. Changed to APS PRL styl
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