Time-frequency signatures of electronic coherence of colloidal CdSe quantum dot dimer assemblies probed at room temperature by 2-dimensional electronic spectroscopy

Abstract

Electronic coherence signatures can be directly identified in the time-frequency maps measured in 2 dimensional spectroscopy (2DES). We demonstrate the theory and discuss the advantages of this approach by a detailed application to the fast femtosecond beatings of a wide variety of electronic coherences in dimers of size-dispersed (8%) 3nm quantum dots (QDs). The observed and computed results can be consistently characterized directly in the time-frequency domain by probing the polarization in a 2DES set-up. Experimental and computed time-frequency maps are found in very good agreement and several electronic coherences are characterized at room temperature in solution before extensive dephasing due to the size-dispersion kicks in. As compared to the frequency-frequency maps that are commonly used in 2DES, the time-frequency maps allow for exploiting electronic coherences without additional post processing and with fewer 2DES measurements. Towards quantum technology applications, we also report on the modeling of the time-frequency photocurrent response of these electronic coherences, which opens the way to integrating QD devices with classical architectures thereby enhancing the quantum advantage of such technologies for parallel information processing at room temperature.