Delmonte, ValentinSpecht, Judith F.Jakubczyk, TomaszHöfling, SvenKamp, MartinSchneider, ChristianLangbein, WolfgangNogues, GillesRichter, MartenKasprzak, Jacek2020-11-192020-11-1920172469-9950https://depositonce.tu-berlin.de/handle/11303/12025http://dx.doi.org/10.14279/depositonce-10905We employ two-dimensional (2D) coherent, nonlinear spectroscopy to investigate couplings within individual InAs quantum dots (QDs) and QD molecules. Swapping pulse ordering in a two-beam sequence permits one to distinguish between rephasing and nonrephasing four-wave mixing (FWM) configurations. We emphasize the nonrephasing case, allowing one to monitor two-photon coherence dynamics. Respective Fourier transform yields a double quantum 2D FWM map, which is corroborated with its single quantum counterpart, originating from the rephasing sequence. We introduce referencing of the FWM phase with the one carried by the driving pulses, overcoming the necessity of its active stabilization, as required in 2D spectroscopy. Combining single and double quantum 2D FWM provides a pertinent tool in detecting and ascertaining coherent coupling mechanisms between individual quantum systems, as exemplified experimentally.en530 PhysikArticle2469-9969