Probing Product Redistribution During Photosynthesis Dark Conditions Using Quantum Imaging with Undetected Photons
Authors:
Joshua Yuan1* ([email protected], PI), Yining Zeng2 ([email protected])
Institutions:
1Washington University in St. Louis; 2National Renewable Energy Laboratory
Abstract
Mitigation of sample photodamage allows for a longer observation window to trace biological processes. In particular, the natural photosynthesis systems that use light to drive chemical reactions are very sensitive to optical imaging, as the probing light itself inevitably perturbs photosynthetic reactions. This challenge has prevented the effective real-time monitoring of photosynthesis reactions in dark conditions, where the chemicals synthesized by light redistribute in the plant. Understanding the mechanism of this redistribution is important to close the circle of knowledge on plant photosynthesis. Direct monitoring of the distribution in dark conditions would provide straightforward evidence but has never been achieved ever due to perturbation from the probing light. To address the above challenge, the team applied quantum imaging with undetected photons (QIUP) to probe the photosynthesis processes using a very low dose of photons.
QIUP uses two beams consisting of entangled photons separated into infrared (IR) and visible wavelengths. The IR photons probe the sample and obtain sample information, but they are not detected by the detector due to the very low sensitivity in the IR range. The visible photons do not touch the sample but carry the sample information through entanglement, and they are detected at high sensitivity and produce sample images. This study demonstrated that QIUP can produce sample images by using only picowatts of illumination power on the sample. The power density is many orders of magnitude lower than that of classic light microscopy, for example, confocal fluorescence microscopy.
Researchers applied QIUP to image squalene in tobacco leaves by using squalene’s IR absorption bands. The illumination power density used in QIUP to achieve similar chemical imaging capability is even more drastically lower than that of stimulated Raman scattering microscopy, which uses a picosecond pulsed laser to induce a high illumination field. The imaging data has informed the metabolic engineering of more efficient squalene production in tobacco.