Ergodic vs diffusive decoherence in mesoscopic devices

Abstract

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).

LaTeX, 5 pages, 4 pdf figures ; v2: revised version

References in corpus (5)

• Magnetic field asymmetry of mesocopic dc rectification in Aharonov Bohm rings
• Dephasing due to electron-electron interaction in a diffusive ring
• Electron coherence at low temperatures: The role of magnetic impurities
• Geometrical dependence of decoherence by electronic interactions in a GaAs/GaAlAs square network
• Effect of connecting wires on the decoherence due to electron-electron interaction in a metallic ring