Numerical Study on Quantum Walks Implemented on the Cascade Rotational   Transitions in a Diatomic Molecule
  We propose an implementation scheme for the continuous-time quantum walk using a diatomic molecule and an optical frequency comb. We show an analogy between the quantum walk and the cascade rotational transitions induced by the optical frequency comb whose frequency peaks are tuned to the pure rotational transitions in the molecule. The strategy to compensate for the centrifugal distortion of the real molecule is also demonstrated. 
Leo Matsuoka, Tatsuya Kasajima, Masashi Hashimoto, and Keiichi   Yokoyama
quant-ph