Nonlocal bias spectroscopy of the self-consistent bound state in quantum point contacts near pinch off

We perform nonlocal bias spectroscopy of the self-consistent bound state (BS) in quantum point contacts (QPCs), determining the lever arm (γ) that governs the gate-voltage induced shift in its energy. The value of γ allows us to infer an enhanced g factor, and large remnant spin splitting, for the BS. Our results show many similarities with bias spectroscopy of quantum dots and are reproduced by calculations that assume a discrete BS coupled to a reservoir. This study therefore provides independent evidence in support of the notion of BS formation in QPCs.