One-dimensional quantised ballistic resistors in parallel configuration

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Abstract
The authors have defined, in parallel configuration, two split gate devices 0.3 mu m long by 0.3 mu m wide with a centre-to-centre separation of 0.5 mu m on a high mobility heterojunction. At low temperatures, when the phase coherence length is longer than the channel length, the conduction through each one is ballistic and shows steps in conductance of 2e2/h. If the phase coherence length is also greater than the channel separation, transport through both channels is no longer independent, but instead the channels act co-operatively, leading to coherent steps in the conductance of 4e2/h; this can be seen even if the channels do not have the same widths. The device shows Aharonov-Bohm oscillators in resistance of amplitude 10%, arising from a current circulating via edge states through both channels, indicating that the electron wavefunctions is indeed coherent through both.