Structural changes in nature and technology are driven by charge carrier
motion. A process such as charge-directed reactivity that can be operational in
radiobiology is more efficient, if energy transfer and charge motion proceeds
along well-defined quantum mechanical pathways keeping the coherence and
minimizing dissipation. The open question is: do long-lived electronic quantum
coherences exist in complex molecules? Here, we use x-rays to create and
monitor electronic wave packets in the amino acid glycine. The outgoing
photoelectron wave leaves behind a positive charge formed by a superposition of
quantum mechanical eigenstates. Delayed x-ray pulses track the induced
electronic coherence through the photoelectron emission from the sequential
double photoionization processes. The observed sinusoidal modulation of the
detected electron yield as a function of time clearly demonstrates that
electronic quantum coherence is preserved for at least 25 femtoseconds in this
molecule of biological relevance. The surviving coherence is detected via the
dominant sequential double ionization channel, which is found to exhibit a
phase shift as a function of the photoelectron energy. The experimental results
agree with advanced ab-initio simulations.Comment: 54 pages, 11 figure