Coherent population oscillations and superluminal light in a protein complex.
We observed superluminal light in aqueous solution of the protein complex bacteriorhodopsin (bR) at 647.1 nm wavelength where it exhibits reverse saturable behavior, exploiting the technique of coherent population oscillations (CPO). With a modulation frequency of 10 Hz, the signal pulse through a 1 cm path cell is ahead by 3 msec relative to the reference pulse, corresponding to a group velocity of -3.3 m/sec. Following our early work on slow light in the same sample at the saturable wavelength 568.2 nm, we now explicitly observed the narrow spectral hole in the absorption band of the stable B state and further, demonstrated a close correlation between the profile of the hole and the corresponding pulse delay for various modulation frequencies. A similar behavior is observed for superluminal light versus antihole blown in the absorption band.
Department of Physics, University of Massachusetts, Boston, MA 02125, USA.
Chandra S
CS
Yelleswarapu
Samir
S
Laoui
Reji
R
Philip
D V G L N
DV
Rao
D001436:Bacteriorhodopsins / Q000737:chemistry*; D001683:Biological Clocks; D003198:Computer Simulation; D008164:Luminescent Proteins / Q000737:chemistry*; D008956:Models, Chemical; D010783:Photometry / Q000379:methods*
D008164:Luminescent Proteins; D001436:Bacteriorhodopsins