Conductance quantization features in multichannel quantum point contacts

A multichannel electron transport mode with independent conductance quantization in individual channels is implemented and studied in quantum point contacts with side gates. Simulation of the total conductance as the sum of quantized individual conductances reproduces the experimentally observed complex conductance dependence on the sum and difference of gate voltages in this regime. The considered model reproduces the following experimentally observed features of conductance quantization: the absence of some of the plateaus, the conductance steps equal to $4{{e}^{2}}{\text{/}}h$ and other values different from $2{{e}^{2}}{\text{/}}h$, the plateaus appearing at non-multiples of $2{{e}^{2}}{\text{/}}h$, the evolution of the anomalous plateaus with a change in gate voltage difference, and the low visibility of some plateaus. The study shows that a non-trivial experimentally observed conductance behavior in quantum point contacts may originate from channel multiplicity which may not be obvious in advance.