Ultrafast Detection and Manipulation of a Persistent Trion Coherence in a Single CdSe/ZnSe Quantum Dot

The lifetime of coherence is a key parameter in several fields of solid-state physics. In particular, the generation, detection and manipulation of long-lived coherences between highly excited states remains challenging. II-VI compound semiconductor quantum dots (QD) represent advantageous spin-to-photon devices in combination with femtosecond light pulses [1] , [2] . In this work, we generate a persistent trion coherence between excited states and detect its evolution via biexcitonic absorption. Pump-probe polarizations provide control over amplitude and phase of the resulting quantum beats, enabling us to investigate the dynamics upon single-electron excitation.