Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion.

Abstract 

A Ramsey-type interferometer is suggested, employing a cold trapped ion and two time-
delayed off-resonant femtosecond laser pulses. The laser light couples to the 
molecular polarization anisotropy, inducing rotational wavepacket dynamics. An 
interferogram is obtained from the delay dependent populations of the final field-free
rotational states. Current experimental capabilities for cooling and preparation of 
the initial state are found to yield an interferogram visibility of more than 80 
percent. The interferograms can be used to determine the polarizability anisotropy 
with an accuracy of about ± 2 percent, respectively ± 5 percent, provided the 
uncertainty in the initial populations and measurement errors are confined to within 
the same limits.