50 research outputs found
Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion
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\%. The interferograms can be used to
determine the polarizability anisotropy with an accuracy of about ,
respectively , provided the uncertainty in the initial populations and
measurement errors are confined to within the same limits
Direct frequency-comb-driven Raman transitions in the terahertz range
We demonstrate the use of a femtosecond frequency comb to coherently drive
stimulated Raman transitions between terahertz-spaced atomic energy levels.
More specifically, we address the and fine
structure levels of a single trapped Ca ion and spectroscopically
resolve the transition frequency to be Hz. The achieved accuracy is nearly a factor of five better than the
previous best Raman spectroscopy, and is currently limited by the stability of
our atomic clock reference. Furthermore, the population dynamics of
frequency-comb-driven Raman transitions can be fully predicted from the
spectral properties of the frequency comb, and Rabi oscillations with a
contrast of 99.3(6)\% and millisecond coherence time has been achieved.
Importantly, the technique can be easily generalized to transitions in the
sub-kHz to tens of THz range and should be applicable for driving, e.g.,
spin-resolved rovibrational transitions in molecules and hyperfine transitions
in highly charged ions.Comment: 9 pages, 8 figure