The two dimensional electron gas (2DEG) formed at the LaAlO₃ (LAO)/SrTiO₃ (STO) has unique characteristics, which were not observed in STO bulk samples. Several magneto-transport studies performed on LAO/STO interfaces, found a diverse behavior of the magneto-resistance (MR). There were reports of MR changing sign under application of external electric field, dependent on relative direction of surface and magnetic field and on relative direction of current and magnetic field orientation, and even showing signs of hysteretic behavior. The negative MR was lately interpreted as a result of weak localization (WL) in a system with strong spin-orbit coupling. However, until now there was no real evidence for phase coherent transport in STO/LAO interfaces allowing such an interpretation. In this talk magneto-transport measurements on mesoscopic devices of LAO/STO will be presented. It will be shown, for the first time, that universal conductance fluctuations (UCF) can be observed in such devices. This proves that phase coherence has a large contribution to the behavior of MR in such interfaces. The agreement of coherence length from UCF and WL measurements suggests that the observed negative MR is as a consequence of WL theory. Based on this understanding, magneto-transport measurements performed on a macroscopic sample in different temperatures allowed us to conclude that the de-phasing rate is dominated by electron-electron interactions.