Finite-bias charge detection in a quantum dot

Abstract

We present measurements on a quantum dot coupled capacitively to a quantum point contact used as a charge detector. The transport current through the dot and the time-averaged charge on the dot are measured simultaneously. At finite bias voltage through the dot, the differential charge signal coincides with some of the Coulomb diamond boundaries and with the signatures from excited states in the dot current. Combining the resulting integrated charge data with the simultaneous measurements of the dot current allows us to estimate the coupling of different energy levels inside the dot to both leads individually.