LN12705 - Eyes of living organisms represent advanced light harvesting systems, developed through hundreds of millions years of evolution. Some of their features are comparable or even superior to existing man-made photodetection devices. For example, rod photoreceptor cells of the retina, which are responsible for night vision and form the focus of the present study, represent miniaturized photodetectors containing a photosensitive element (rhodopsin pigment) along with a ‘‘built-in’’ chemical power supply (ATP produced by mitochondria). They have sensitivity down to single-photon level, and demonstrate a remarkable low noise operation. Understanding such properties of nature-given photodetectors stimulates considerable interest in interfacing them with sources of nonclassical light, such as light with a ‘‘fixed’’ number of photons, and ‘‘squeezed’’ light. We analyzed the electrophysiological response of an isolated rod photoreceptor of the African Clawed Frog (Xenopus laevis) under stimulation by coherent and pseudothermal light sources. Using the suction-electrode technique for single cell recordings and a fiber optics setup for light delivery allowed measurements of the major statistical characteristics of the rod response. The results indicate differences in average responses of rod cells to coherent and pseudothermal light of the same intensity and also differences in signal-to-noise ratios and second-order intensity correlation functions. These findings should be relevant for interdisciplinary studies seeking applications of quantum optics in biology.
Thursday, August 2, 2012
Studying the Light Response of Living Photoreceptor Cells
LN12705 - Eyes of living organisms represent advanced light harvesting systems, developed through hundreds of millions years of evolution. Some of their features are comparable or even superior to existing man-made photodetection devices. For example, rod photoreceptor cells of the retina, which are responsible for night vision and form the focus of the present study, represent miniaturized photodetectors containing a photosensitive element (rhodopsin pigment) along with a ‘‘built-in’’ chemical power supply (ATP produced by mitochondria). They have sensitivity down to single-photon level, and demonstrate a remarkable low noise operation. Understanding such properties of nature-given photodetectors stimulates considerable interest in interfacing them with sources of nonclassical light, such as light with a ‘‘fixed’’ number of photons, and ‘‘squeezed’’ light. We analyzed the electrophysiological response of an isolated rod photoreceptor of the African Clawed Frog (Xenopus laevis) under stimulation by coherent and pseudothermal light sources. Using the suction-electrode technique for single cell recordings and a fiber optics setup for light delivery allowed measurements of the major statistical characteristics of the rod response. The results indicate differences in average responses of rod cells to coherent and pseudothermal light of the same intensity and also differences in signal-to-noise ratios and second-order intensity correlation functions. These findings should be relevant for interdisciplinary studies seeking applications of quantum optics in biology.
