Chemistry Department Colloquium

Coherence phenomena arise from interference, or the addition, of wave-like amplitudes in phase. While coherence has been shown to yield transformative new ways for improving function, advances have been limited to pristine matter, as quantum coherence is considered fragile. Recent evidence of coherence in chemical and biological systems, however, concludes that the phenomena is robust and can survive in the face of disorder and noise. I will present the state of recent discoveries. For example, two-dimensional electronic spectroscopy data allow quantitative analysis of vibronic coherence in the photosynthetic light harvesting complexes [1]. I will show how vibronic coherence plays a special role in downhill energy transfer, increasing energy transfer rates remarkably—even when electronic coupling is weak [2]. I will discuss how coherence might be found in electron transfer reactions. I will conclude with a forecast for the role of function as a design element in realizing coherence [3].

[1] Scholes, et al. "Lessons from nature about solar light harvesting" Nature Chem. 3, 763–774 (2011).
[2] Dean et al. "Vibronic Enhancement of Algae Light Harvesting" Chem (Cell Press) 1, 858–872 (2016).
[3] Scholes, et al. "Optimal Coherence in Chemical and Biophysical Dynamics" Nature 543, 647–656 (2017).