1206.0757 (Thibaut Capron et al.)

Ergodic vs diffusive decoherence in mesoscopic devices    [PDF]

Thibaut Capron, Christophe Texier, Gilles Montambaux, Dominique Mailly, Andreas D. Wieck, Christopher Bäuerle, Laurent Saminadayar

We report on the measurement of phase coherence length in a high mobility two-dimensional electron gas patterned in two different geometries, a wire and a ring. The phase coherence length is extracted both from the weak localization correction in long wires and from the amplitude of the Aharonov-Bohm oscillations in a single ring, in a low temperature regime when decoherence is dominated by electronic interactions. We show that these two measurements lead to different phase coherence lengths, namely $L_{\Phi}^\mathrm{wire}\propto T^{-1/3}$ and $L_{\Phi}^\mathrm{ring}\propto T^{-1/2}$. This difference reflects the fact that the electrons winding around the ring necessarily explore the whole sample (ergodic trajectories), while in a long wire the electrons lose their phase coherence before reaching the edges of the sample (diffusive regime).

View original: http://arxiv.org/abs/1206.0757