Correlation Measurement of Time-Dependent Potentials in a Semiconductor Quantum Point Contact

A novel time-correlation measurement technique is proposed and demonstrated to investigate time-dependent potentials in nanostructures. We focus on a semiconductor quantum point contact, in which the tunneling barrier potential and the source–drain bias potential can be independently controlled by external voltage pulses. Time-correlation of the two potentials is obtained by measuring the dc current at various time differences between the two pulses. The observed correlation function is consistent with the model and can be used to evaluate the waveform of the time-dependent potential.