Tuesday, August 6, 2013

1308.0670 (Nam Mai Phan et al.)

Controllable single photon stimulation of retinal rod cells    [PDF]

Nam Mai Phan, Mei Fun Cheng, Dmitri A. Bessarab, Leonid A. Krivitsky
Retinal rod cells are commonly assumed to be sensitive to single photons [1, 2, 3]. Light sources used in prior experiments exhibit unavoidable fluctuations in the number of emitted photons [4]. This leaves doubt about the exact number of photons used to stimulate the rod cell. In this letter, we interface rod cells of Xenopus laevis with a light source based on Spontaneous Parametric Down Conversion (SPDC) [5], which provides one photon at a time. Precise control of generation of single photons and directional delivery enables us to provide unambiguous proof of single photon sensitivity of rod cells without relying on the statistical assumptions. Quantum correlations between single photons in the SPDC enable us to determine quantum efficiency of the rod cell without pre-calibrated reference detectors [6, 7, 8]. These results provide the path for exploiting resources offered by quantum optics in generation and manipulation of light in visual studies. From a more general perspective, this method offers the ultimate tool for studying intrinsic characteristics of photoinduced biological processes at the single and discrete photon level [9].
View original: http://arxiv.org/abs/1308.0670

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