Prof.Yigal Meir (Ben-Gurion University, Israel, http://www.bgu.ac.il/~ymeir)

Time: 11:00 hrs

Location: QT Library 

The 0.7 anomaly in quantum point contacts

The conductance through a quantum point contact exhibits integer steps of G_0=2e2/h. In addition, one observes an additional shoulder at a value around 0.7xG_0, an observation which remained a puzzle for a couple of decades. I will discuss the history of the effect and demonstrates how the phenomenology of this "0.7 anomaly" can be fully explained in terms of a quasi-localized state, which forms as the point contact opens up. Detailed numerical calculations within spin-density functional theory indeed confirm the emergence of such a state.

Quantitative calculations of the conductance and the noise are obtained using a model based on these observations, and are in excellent agreement with existing experimental observations. Lastly, the possibility of observing two-impurity Kondo physics is such a system will be discussed.