Time‐resolved single‐electron wave‐packet detection

We discuss a time‐resolved method of detecting single‐electron wave packets traveling in quantum‐Hall edge states. The electron arrival‐time distribution is measured by applying a time‐dependent potential to a detector potential barrier. Using numerical calculations, we show that picosecond time resolutions can be achieved by increasing the rate of change in the barrier potential. We also show comparisons between the calculations and a set of experimental data, to demonstrate that picosecond time resolutions are possible within realistic experimental conditions. We examine the relationship between the full‐width‐at‐half‐maximum of measured temporal distribution and the underlying arrival‐time distribution. As the rate of barrier change increases, we observe the measured width to reach a minimum at 6.4 ps. Our analysis suggests that the arrival‐time distribution can be as small as 1 ps. However, we also find that the presence of energy–time correlations in the probability‐density distribution can distort the measurement results, and the arrival‐time distribution may be actually as broad as ∼10 ps. Visualization of the probability density ρ(E,t) of electron wave packets in the energy–time space used for the analysis of arrival‐time distribution.