Dephasing Time in a Two-Dimensional Electron Fermi Liquid

The observation of coherent quantum transport phenomena in metals and semiconductors is limited by the eventual loss of phase coherence of the conducting electrons. We use the weak localization effect to measure the low-temperature dephasing time in a two-dimensional electron Fermi liquid in GaAs/AlGaAs heterostructures. We use a novel temperature calibration method based on the integer quantum Hall effect in order to directly measure the electrons' temperature. The data are in excellent agreement with recent theoretical results, including contributions from the triplet channel, for a broad temperature range. We see no evidence for saturation of the dephasing time down to around 100mK. Moreover, the zero-temperature dephasing time is extrapolated to be higher than 4ns.