Locally induced quantum interference in scanning gate experiments

We present conductance measurements of a ballistic circular cavity influenced by a scanning gate. In contrast to previous studies, we demonstrate the use of scanning gate microscopy as a tool for tailoring the potential landscape of nanostructures with a high degree of control. When the tip depletes the electron gas below, we observe very pronounced and regular fringes covering the entire cavity. The fringes correspond to transmitted modes in constrictions formed between the tip-induced potential and the boundaries of the cavity. Moving the tip and counting the fringes gives us exquisite control over the transmission of these constrictions. We use this control to form a quantum ring with a specific number of modes in each arm showing the Aharonov–Bohm effect in low-field magnetoconductance measurements.