Transport through short quantum wires

Original · EN

At temperatures T < ℏ vF/KB d ≡ Twire the collective excitations are negligible and the spectrum of the short wire is dominated by the ''zero modes'' particle excitations. At temperature T > Twire a spin polarized state controlled by the electron-electron interaction and electron density is identified at short times. As a result the anomaly in the conductance G > 2 × 0.5 e²/h appears. At T → 0 by varying the gate voltage we find that our problem is equivalent to a resonant impurity level. As a result perfect transmission with a conductance G ≃ 2 e²/h is obtained. The model presented here can be used as a spin filter which operate by varying the temperature. Transport through a short quantum wire with electron-electron interaction and length ``d'' coupled to Luttinger leads is considered. The short wire model might explain the ``0.7 anomaly'' observed in quantum point contacts.