Measuring Quantum Coherence in Molecules, Semiconductors, and Proteins using 2D Electronic Spectroscopy

Abstract:

Recent studies using 2D electronic spectroscopy have suggested that electronic coherence is maintained in light-harvesting proteins for an exceptionally long time, hundreds of femtoseconds at physiological temperatures.  This leads to speculations about the presence of quantum-mechanical effects such as entanglement.  However, the experiment can also excite vibrational wavepackets, whose signatures are almost identical to electronic coherences.  Here we examine how electronic and vibrational coherences can be distinguished by careful investigation of the cross peak oscillations in several different samples.  Our conclusion is that both electronic and vibrational coherences are present in the light-harvesting protein we measured.