Many-body enhanced nonlinear conductance resonance in quantum channels

We measure a strong enhancement of the nonlinear differential conductance (g=dI/dV), the amplitude of which exceeds the universal quantum conductance (2e2/h), under finite bias voltage in quantum point contacts (QPCs). By developing a spin-based model in the low-electron-density limit, we demonstrate that this resonance is an intrinsic nonequilibrium phenomenon that arises from many-body induced modifications to the QPC potential. A comparison with the linear conductance (G=I/V) shows that this phenomenon is driven by many-body dynamics within a single one-dimensional sub-band.