Berlin 2001 – wissenschaftliches Programm
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Q: Quantenoptik
Q 17: Poster: Cooling and Trapping
Q 17.26: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT2
Modulation techniques in a molecular Ramsey-Bordé interferometer — •Christian Lisdat, Matthias Frank, Horst Knöckel, and Eberhard Tiemann — SFB 407, Institut für Quantenoptik, Universität Hannover
On the example of a matter wave interferometer with K2 molecules, we
present different methods to simplify the observed interference structures
superimposed on a spectral line split up by hyperfine interaction. The
interferometer is of the Ramsey-Bordé type and uses transitions from the
ground state X 1Σg+ to the state b 3Πu (0+).
The experiments were performed in the framework of investigations of
collisions between K2 molecules and potassium atoms within the
interferometer. The aim is to improve the accuracy of measuring the phase
of the interference pattern, which contains the information about the
collision process.
We consider optical pumping by additional laser fields for the depletion of
population of some ground state hyperfine levels to prepare a quantum
state, that leads to non-blending transitions in the interferometer.
In connection with lock-in technique amplitude modulation as well as
frequency modulation of laser beams of the interferometer is investigated
to subtract or reduce the incoherent envelope of one or several
interference patterns. The influence of amplitude modulation of the
depletion laser and lock-in detection is discussed as well.
As follow-up treatment digital filtering is demonstrated, which uses a
Fourier transform high-pass filter to separate the interference patterns
from the envelope of the spectral line.