Sympathetic Cooling of Large Molecules in a Cold-Atom Trap

• Antragsteller: Professor Dr. Hanspeter Helm
• Fachliche Zuordnung: Optik, Quantenoptik und Physik der Atome, Moleküle und Plasmen
• Förderung: Förderung in 2008
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 97830361

• Erstellungsjahr: 2013

Zusammenfassung der Projektergebnisse

Quantum chemistry and computational chemistry can nowadays determine to a high degree of precision internal energy states of even large molecules. Likewise molecular dynamics methods permit time- and space-resolved views of changes in molecular structure, which may occur following interaction with external force fields. Experimental access to microscopic views of such change is generally limited to ensemble averages in an uncontrolled environment to which the molecule is strongly coupled. Our project aimed at resolving the stochastic development of internal energy states of a single large molecule in a controlled environment. A number of requisites for such a study were sucessfully pursued. For one it appears clear that sympathetic cooling of the molecule would provide the lowest temperature environment for the preparation. Long term observations demand a continuous supply of coolant atoms in this process. While an optical dipole trap is a most promising environment for storage of the molecule, current preparation methods of very cold atoms to be used as refrigerant rely on pulsed processes such as evaporative cooling. Here we explored means of continuous cooling based on electromagnetically induced transparency. For this purpose a wide range of studies on dark superposition states of atoms were undertaken, specifically their dynamic response to external frequency shifts, to ac-Stark shifts, to stochastic and deliberate phase shifts of the external laser fields.

Projektbezogene Publikationen (Auswahl)

• Trapped-atom cooling beyond the Lamb-Dicke limit using electromagnetically induced transparency. Physical Review A 77 043418 (2008)
  M. Roghani and H. Helm
  
• Ejection of magnetic-field-sensitive atoms from an optical dipole trap. Physical Review A 80 023409 (2009)
  C. Käfer, R. Bourouis, J. Eurisch, A. Tripathi, and H. Helm
  
• Stern-Gerlach experiments with Bose-Einstein condensates and the introduction of a new thermometry method in an optical dipole trap. PhD Thesis
  Christoph Käfer
  
• Quantitative analysis of the transient response of the refractive index to conditions of electromagnetically induced transparency. Physical Review A 85 013820 (2012)
  F. Meinert, C. Basler, A. Lambrecht, S. Welte, and H. Helm
  
• Phase control and diagnostic of quantum mechanical superposition state. Physical Review A 87 134430 (2013)
  C. Basler, K. Reininger, F. Meinert, P. N. Ghosh, and H. Helm