Physical Review E
66
(4)
041111
(2002)
| Journal
| PDF
We analyze a model of a nonlinear bath consisting of a single two-level system coupled to a linear bath (a classical noise force in the limit considered here). This allows us to study the effects of a nonlinear, non-Markoffian bath in a particularly simple situation. We analyze the effects of this bath onto the dynamics of a spin by calculating the decay of the equilibrium correlator of the z-component of the spin. The exact results are compared with those obtained using three commonly used approximations: a Markoffian master equation for the spin dynamics, a weak-coupling approximation, and the substitution of a linear bath for the original nonlinear bath.
Visibility of the Aharonov-Bohm effect in a ring coupled to a fluctuating magnetic flux (vol 126, pg 1325, 2002)
F Marquardt,
C Bruder
Journal of Low Temperature Physics
128
(3-4)
UNSP 0022-2291/02/0800-0163/0
163-163
(2002)
CORRECTION
Aharonov-Bohm ring with fluctuating flux
F Marquardt,
C Bruder
Physical Review B
65
(12)
125315
(2002)
| Journal
| PDF
We consider a noninteracting system of electrons on a clean one-channel Aharonov-Bohm ring that is threaded by a fluctuating magnetic flux. The flux derives from a Caldeira-Leggett bath of harmonic oscillators. We address the influence of the bath on the following properties: one- and two-particle Green's functions, dephasing, persistent current, and visibility of the Aharonov-Bohm effect in cotunneling transport through the ring. For the bath spectra considered here (including Nyquist noise of an external coil), we find no dephasing in the linear transport regime at zero temperature.
Separation quality of a geometric ratchet
C Keller,
F Marquardt,
C Bruder
Physical Review E
65
(4)
041927
(2002)
| Journal
| PDF
We consider an experimentally relevant model of a geometric ratchet in which particles undergo drift and diffusive motion in a two-dimensional periodic array of obstacles, and which is used for the continuous separation of particles subject to different forces. The macroscopic drift velocity and diffusion tensor are calculated by a Monte Carlo simulation and by a master-equation approach, using the corresponding microscopic quantities and the shape of the obstacles as input. We define a measure of separation quality and investigate its dependence on the applied force and the shape of the obstacles.
Visibility of the Aharonov-Bohm effect in a ring coupled to a fluctuating magnetic flux
F Marquardt,
C Bruder
Journal of Low Temperature Physics
126
(3-4)
1325-1337
(2002)
| Journal
| PDF
We consider the visibility of the Aharonov-Bohm effect for cotunneling transport through a clean one-channel ring coupled to a fluctuating magnetic flux. We concentrate on the modification of the destructive interference at Phi(0)/2 by the fluctuating flux, since changes in the magnitude of the current away from this point can also be caused by renormalization effects and do not necessarily indicate dephasing. For fluctuations arising from the Nyquist noise in an external coil at T = 0, the suppression of the destructive interference shows up only in a contribution proportional to V-3, and therefore does not affect the linear conductance. In this sense, the Nyquist bath does not lead to dephasing in the linear transport regime at zero temperature in our model.
Kontakt
Theorie-Abteilung Prof. Florian Marquardt
Max-Planck-Institut für die Physik des Lichts Staudtstr. 2 91058 Erlangen
Für Anfragen aller Art kontaktieren Sie uns bitte unter:
