Coherent population trapping (CPT) and electromagnetically induced transparency in atoms have garnered enormous attention because of their conceptual novelty in quantum optics and potential applications in quantum information processing. Here, we show that CPT can occur in buckminsterfullerene
C60. If we radiate
C60 with a cw coupling field first and then with a weak probe field,
C60 becomes much less absorptive. Turning off the coupling field restores the absorptive nature. Using two coupling pulses, we can prepare
C60 in a dark state, which is transparent to the probe field. Such a dark state sensitively depends on the laser field amplitude, pulse durations, time delay between two coupling pulses, and laser chirps. Too strong fields refill the ground state, while too long durations overshoot the population and become less effective. There is an optimal delay between two pulses. By employing the first-principles method and solving the Liouville equation dynamically, we scan the vast laser parameter space and find a practical path to coherent population trapping in
C60, which is of great importance for future experimental investigations.
We have investigated the atomic coherent population trapping in a multilevel laser-induced continuum structure system including cascade two-photon processes, in which two sets of quasicontinua of excited levels to be modeled as the Bixon-Jortner quasicontinuum are laser-embedded into a previously structureless atomic continuum. The condition leading to the atomic coherent population trapping and the coherent population trapping state are given explicitly. And the effects of the Fano factors, the laser intensities and the detunings on the amount of population trapped in the atomic bound states and the populations distributed in the two sets of quasicontinua are also examined.