Light-harvesting efficiency cannot depend on optical coherence in the absence of orientational order

Dominic M Rouse, Adesh Kushwaha, Stefano Tomasi, Brendon W Lovett, Erik M Gauger, Ivan Kassal*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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The coherence of light has been proposed as a quantum-mechanical control for enhancing light-harvesting efficiency. In particular, optical coherence can be manipulated by changing either the polarization state or the spectral phase of the light. Here, we show that, in weak light, light-harvesting efficiency cannot be controlled using any form of optical coherence in molecular light-harvesting systems and, more broadly, those comprising orientationally disordered subunits and operating on longer-than-ultrafast time scales. Under those conditions, optical coherence does not affect the light-harvesting efficiency, meaning that it cannot be used for control. Specifically, polarization-state control is lost in disordered samples or when the molecules reorient on the time scales of light harvesting, and spectral-phase control is lost when the efficiency is time-averaged over a period longer than the optical coherence time. In practice, efficiency is always averaged over long times, meaning that coherent optical control is only possible through polarization and only in systems with orientational order.
Original languageEnglish
Pages (from-to)254-261
Number of pages8
JournalThe Journal of Physical Chemistry Letters
Issue number1
Early online date2 Jan 2024
Publication statusPublished - 11 Jan 2024


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