Interacting Electrons in a Nearly Straight Quantum Wire

Conductance steps in various types of quantum wire have now been observed, following the pioneering work in Refs. [1]. These first experiments were performed on gated two-dimensional electron gas (2DEG) structures, though similar behaviour has now been observed in other quantum wire structures [2]. Whilst these experiments strongly support the idea of ballistic conductance in quantum wires, and are in surprising agreement with the now standard Landauer-Buttiker formalism [3], certain anomalies can arise which are spin-dependent and are believed to originate from electron-electron interactions. In particular, already in early experiments a structure is seen in the rising edge of the conductance curve [1], starting at around G = 0.7(2e2/h) and merging with the first conductance plateau with increasing energy. Later experiments also clearly showed anomalies near G = 0.25(2e2/h) [2]. Recently we have shown that these conductance anomalies are consistent with an electron being weakly bound in wires of circular and rectangular cross-section, giving rise to spin-dependent scattering resonances [4].