  Bound-state (BS) formation in quantum point contacts (QPCs) may offer a
convenient way to localize and probe single spins. In this letter, we
investigate how such BSs are affected by monitoring them with a second QPC,
which is coupled to the BS via wavefunction overlap. We show that this coupling
leads to a unique detector backaction, in which the BS is weakened by
increasing its proximity to the detector. We also show, however, that this
interaction between the QPCs can be regulated at will, by using an additional
gate to control their wavefunction overlap.

Strongly Correlated Electrons