The plateaus arise from almost perfect electron transmission through 1D-energy subbands of the channel, each contributing a quantity G 0 to the conductance, whose number increases with the channel width. Upon widening the channel by tuning the gate voltage, one observes a staircase increase in the conductance, displaying distinct plateaus at integer multiples of G 0. The channel is defined by a voltage applied to a pair of finger-like gates deposited on the top of heterostructure. The constriction behaves like a quasi-one-dimensional conducting channel. Short, narrow constrictions connecting two reservoirs of two-dimensional electron gas (2DEG) in semiconductor heterostructures, called quantum point contacts, exhibit at low temperature a quantization of the ballistic conductance in units of G 0 = 2e 2/h (e and h are the elementary charge and the Planck’s constant, respectively, and the factor 2 arises from spin degeneracy). Received 5 July 2016 accepted 9 August 2016 published 12 August 2016 A recipe for experimental verification of the model is given. Electron’s resonance can also explain an unusual temperature behavior of the anomaly as well as its recently discovered feature: oscillatory modulation as a function of the channel length and electrostatic potential. “Visibility” of electron is enhanced if the electron spends some time in the channel due to resonant transmission. It is shown that then the QPC-conductance is reduced by a factor of 0.74. The act of observation destroys superposition of spin states, in which the electron otherwise exists, and this suppresses their quantum interference. It is noticed that just after opening a quasi-1D conducting channel in the QPC a single electron travels the channel at a time, and such electron can be-in principle-observed. Here, a unique model of this anomaly is proposed relying on fundamental principles of quantum mechanics. Despite a tremendous amount of research on this anomalous feature, its origin remains still unclear. Apart from usual quantization steps on the ballistic conductance of quasi-one-dimensional conductor, an additional plateau-like feature appears at a fraction of about 0.7 below the first conductance step in GaAs-based quantum point contacts (QPCs).
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