1,036 research outputs found
Shot-noise in transport and beam experiments
Consider two Fermi gases with the same {\it average} currents: a transport
gas, as in solid-state experiments where the chemical potentials of terminal 1
is and of terminal 2 and 3 is , and a beam, i.e., electrons
entering only from terminal 1 having energies between and . By
expressing the current noise as a sum over single-particle transitions we show
that the temporal current fluctuations are very different: The beam is noisier
due to allowed single-particle transitions into empty states below .
Surprisingly, the correlations between terminals 2 and 3 are the same.Comment: 4 pages, 2 figure
Pairing and persistent currents - the role of the far levels
We calculate the orbital magnetic response to Aharonov Bohm flux of
disordered metallic rings with attractive pairing interaction. We consider the
reduced BCS model, and obtain the result as an expansion of its exact solution
to first order in the interaction. We emphasize the connection between the
large magnetic response and the finite occupation of high energy levels in the
many-body ground state of the ring.Comment: 10 pages, contribution to MS+S200
Steps and dips in the ac conductance and noise of mesoscopic structures
The frequency dependence of the equilibrium ac conductance (or the noise
power spectrum) through a mesoscopic structure is shown to exhibit steps and
dips. The steps, at energies related to the resonances of the structure, are
closely related to the partial Friedel phases of these resonances, thus
allowing a direct measurement of these phases (without interferometry). The
dips in the spectrum are related to a destructive interference in the
absorption of energy by transitions between these resonances, in some
similarity with the Fano effect.Comment: 4 pages, 2 figure
Transmission of two interacting electrons
The transmission of two electrons through a region where they interact is
found to be enhanced by a renormalization of the repulsive interaction. For a
specific example of the single-particle Hamiltonian, which includes a strongly
attractive potential, the renormalized interaction becomes attractive, and the
transmission has a pronounced maximum as function of the depth of the
single-electron attractive potential. The results apply directly to a simple
model of scattering of two interacting electrons by a quantum dot.Comment: 12 pages, 2 figure
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