Infrared Quantum Ghost Imaging Illuminates—But Doesn’t Disturb—Living Plants

The Science

A method called quantum ghost imaging (QGI) allows scientists to capture images at extremely low light levels. QGI also enables the use of one low intensity color, best matched to the sample and a different color at higher intensity sufficient to form the image of the sample. This approach improves imaging in regions of light where traditional cameras struggle. By employing a novel detector, researchers obtained clear images of living sorghum plants with a light far dimmer than starlight. This advance enables imaging of delicate, light-sensitive samples, such as biofuel crops, without disturbing or damaging the plants.

The Impact

QGI offers key advantages for plant research. This ultra-sensitive technique allows for detailed monitoring of plant health and growth without exposing the crops to harmful light levels, which could stress or damage the plants. QGI also removes the need to insert dyes or other “labels” into plants. These labels can help researchers view microscopic features, but they can also interfere with plant processes. By using label-free infrared imaging, researchers can gather critical information about important plant processes, such as water content and photosynthesis, even in low-light conditions. This is particularly beneficial for studying biofuel crops, where researchers want to optimize plant growth and health to maximize yield and sustainability.

Summary

Quantum ghost imaging (QGI) measures the absorption of light at extremely low light intensities. Non-degenerate QGI probes a sample at one wavelength while forming an image with correlated photons at a different wavelength. This spectral separation alleviates the need for imaging detectors with high sensitivity in the near-infrared region, thereby reducing the required illumination intensity. Using NCam, a novel single-photon detector, researchers demonstrated non-degenerate QGI with unprecedented sensitivity and contrast, obtaining images of living plants with less than 1% light transmission. The plants were imaged with a photon flux that is orders of magnitude below starlight. The method used infrared light to the plant to detect chemicals that can only be seen with these wavelengths, and visible light where detectors are better designed.

This realization of QGI expands the method to extremely low light bioimaging and imaging of light-sensitive samples, where minimizing illumination intensity is crucial to prevent phototoxicity or sample degradation. This study demonstrated live plant imaging of several representative plant samples, including the biofuel crop sorghum. This work was performed, in part, at the Center for Integrated Nanotechnologies, a Department of Energy Office of Science user facility.

Funding

This research was supported by the Department of Energy (DOE) Office of Science, Biological and Environmental Research, Biological Characterization and Imaging Science Program. This work was performed, in part, at the Center for Integrated Nanotechnologies, a DOE Office of Science user facility at Los Alamos National Laboratory.