Origin of zero‑delay waveform fluctuations

Determine the physical origin of the fluctuating structure observed within approximately 6 picoseconds around the nominal zero pump–probe delay in the asynchronous optical sampling optical pump–optical probe differential transmission waveform of the cryogenically cooled InAs quantum‑dot ensemble, and disentangle possible contributions from suboptimal pulse compression, pulse‑shape distortions, and detector temporal resolution limitations.

Background

In the quantum‑beat analysis, the waveform near the nominal zero delay exhibits fine structure on a few‑picosecond scale. The experiment’s effective temporal resolution is about 6 ps due to pulse durations and detector bandwidth, and the exact zero‑delay position is uncertain on a similar timescale. Because of these limitations, the authors could not isolate the source of the observed fine structure near time zero.

Resolving this uncertainty matters because the early‑time region sets the time‑origin for fitting and can subtly influence extracted parameters and their systematic uncertainties.

References

The origin of the fluctuating structure cannot be uniquely identified because the effective instrument response is limited by the \SI[number-unit-separator=\text{-}]{6}{\pico\second} pulse duration, which reflects suboptimal pulse compression, pulse-shape distortions, and the time resolution of the detector.

— Spatial mapping of quantum-dot dynamics across multiple timescales at low temperature using remote asynchronous optical sampling  (2604.03041 - Asambo et al., 3 Apr 2026) in Subsubsection "Discussion" (Sec. III‑B2)