Ultracold electronically excited atoms in magnetic microtraps

• Applicant: Professor Dr. Peter Schmelcher
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2004 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5437316

• Final Report Year: 2012

Final Report Abstract

This project was dedicated to the investigation of Rydberg atoms in inhomogeneous magnetic fields, covering both the case of microtraps with strong gradients as well as macroscopic traps. As a first step we studied in detail the electronic structure for fixed nucleus and the intricate spin-spatial patterns of Rydberg atoms. A number of unusual properties were unraveled such as a magnetic field-induced electric dipole moment. Even in the ultracold regime, the center of mass and electronic motion are coupled. After o developing the theoretical framework to treat the corresponding Schr¨dinger equation magnetic trapping of the Rydberg atoms in 3D quadrupole fields was studied first. The main result here was the fact that close to circular Rydberg atoms can be trapped in this configuration. A method to solve the coupled differential equation of the center of mass and electronic motion was developed. The latter served as a powerful tool which was used in further investigations and in particular for other magnetic field configurations. It turns out that the Ioffe-Pritchard magnetic field configuration allows to trap Rydberg atoms magnetically even for low angular momentum values. A further major step was performed by showing that the combination of magnetic and electric fields allow for the preparation of a one-dimensional gas of highly polarized Rydberg atoms repelling each other and being stable if endcaps are employed. This represents a strongly correlated long-range interacting quantum gas. One point of emphasis in the second funding period was the dressing of ultracold Rydberg atoms in a Ioffe-Pritchard trap. This allows to modify significantly the trapping potentials for ground state atoms by admixing a small portion of the Rydberg wave function to the ground state wave function. Here, the composite character of Rydberg atoms, consisting of a finite size electronic wave function and a center of mass wave function, can be exploited and should show up also in the time-of-flight experimental observation. Finally, we have treated the very complex case of a one-dimensional gas of Rydberg atoms with a coupled center of mass and electronic motion. Here we showed that an interaction-induced stabilization of circular Rydberg atoms can occur.

Publications

• Magnetic Trapping of Ultracold Rydberg Atoms. Physical Review Letters 95, 053001 (2005)
  I. Lesanovsky and P. Schmelcher
  
• Quantum States of Ultracold Electronically Excited Atoms in a Magnetic Quadrupole Trap. Physical Review A 72, 053410 (2005)
  I. Lesanovsky and P. Schmelcher
  
• Controlling Ultracold Rydberg Atoms in the Quantum Regime. Physical Review Letters 97, 223001 (2006)
  B. Hezel, I. Lesanovsky and P. Schmelcher
  
• One-Dimensional Rydberg Gas in a Magneto-Electric Trap. Physical Review Letters 99, 113005 (2007)
  M. Mayle, B. Hezel, I. Lesanovsky and P. Schmelcher
  
• Ultracold Rydberg Atoms in a Ioffe-Pritchard Trap. Physical Review A 76, 053417 (2007)
  B. Hezel, I. Lesanovsky and P. Schmelcher
  
• Magnetic Trapping of Low-Angular Momentum States of Ultracold Rydberg Atoms. Physical Review A 80, 053410 (2009); Virtual Journal of Quantum Information
  M. Mayle, I. Lesanovsky and P. Schmelcher
  
• Mapping the Composite Character of Magnetically Trapped Rydberg Atoms. Physical Review A (Rapid Communications) 79, 041403 (2009)
  M. Mayle, I. Lesanovsky and P. Schmelcher
  
• Interaction-Induced Stabilization of Circular Rydberg Atoms in Magnetoelectric Traps. Physical Review A 84, 063402 (2011)
  B. Hezel, M. Mayle and P. Schmelcher