Quantum Control

The quantum control activities in AMO at PULSE go beyond attoscience and strong field physics.  The Bucksbaum group has a significant program supported by the National Science Foundation to study strong field quantum control.  This work is centered in PULSE laboratories in the Varian Physics Building on the Stanford University main campus. 

Quantum Control Instrumentation

Molecular Beam Machine

We have been operating a molecular beam machine designed to study quantum control in the gas phase.  Our beam machine utilizes both ion mass spectroscopy and electron time-of-flight spectroscopy, and in the past year we have added the very powerful new capability of velocity map imaging.  Molecules may be intercepted by as many as three collinear laser beams of different colors, intensities, and polarizations, which permit us to study ultrafast and strong field processes.

Ultrafast pulse shapers

We operate acousto-optic ultrafast pulse shapers designed to shape pulses in the ultraviolet, particularly in the vicinity of 266nm, and anywhere in the visible spectrum.  We have a full complement of Ti:Sapphire based pulses available as well, including doublers, triplers, NOPA’s and a TOPAZ infrared OPA. 

Strong field alignment experiments

We have impulsive and adiabatic alignment capabilities  in addition to our pulse-shaped impulsive alignment capabilities. 

Velocity Map Imaging

We now have  the ability to map the momentum distribution of fragments produced by coulomb explosion or uv dissociative ionization.  The VMI provides a richer data set for our work on correlation analysis

Quantum Control Current Projects

Strong field control of CHD ring opening:

We are developing an analysis technique based on Principal Component Analysis (PCA) for determining the number of fragmentation patterns and for estimating their mass fragmentation spectra without a priori knowledge of the number of species present. The technique benefits from the richness of information contained in the complete time-of-flight fragmentation mass spectrum, and not only a subset of peaks.  This technique is especially useful in cases where one (or more) of the molecules involved is transient or otherwise not available for direct study. Using that technique, we are investigating the fragmentation patterns of channels in the TOF spectra collected during the UV-initiated isomerization of CHD.  

Conical intersections in photo-induced reactions

We are examining the role of strong fields on the excited state dynamics in the vicinity of conical intersections.  This is a collaboration with PULSE scientist Todd Martinez and his group.  Our preliminary findings indicate that pulse shaping parameters of pulse wavelength, polarization, and intensity all can affect the manner of passage through conical intersections, and thus affect nonradiative relaxation of electronically excited molecules.

 LCLS

We have recently completed an LCLS investigation on photoinduced ring opening, and have collected a wealth (13 Terabytes!) of VMI and ITOF data, both in uv-pump, x-ray probe experiments, and on the same experiments in the presence of a strong uv field to affect the conical intersection dynamics. 

 PULSE Research Atomic and Molecular Dynamics • Publications • Scientific Staff