Sensing electrons during an adiabatic coherent transport passage

Abstract

We study the detection of electrons undergoing coherent transfer via adiabatic passage (CTAP) in a triple quantum-dot system with a quantum point contact sensing the charge of the middle dot. In the ideal scenario, the protocol amounts to perfect change transfer between the external dots with vanishing occupation of the central dot at all times, rendering the measurement and its backaction moot. Nevertheless, even with minor corrections to the protocol, a small population builds up in the central dot. We study the measurement backaction using a Bayesian formalism simulation of an instantaneous detection at the time of maximal occupancy of the dot. We show that the interplay between the measurement backaction and the nonadiabatic dynamics induces a change in the success probability of the protocol, which quantitatively agrees with a continuous detection treatment. We introduce a correlated measurement signal to certify the nonoccupancy of the central dot for a successful CTAP protocol, which, in the weak-measurement limit, confirms a vanishing occupation of the central dot. Our proposed correlated signal purports the proper experimental method by which to confirm CTAP.