Investigators: Azure Hansen, Justin T. Schultz, Joseph D. Murphree, and N.P. Bigelow (recent graduates)
The Bigelow group studies vortices in BECs both experimentally and theoretically. Our most recent experiments focus on spin textures and topological excitations of a spinor BEC, singular atom optics, and imaging the complex spinor wavefunction of a BEC.
1997 and 2001, and NOVA's Absolute Zero site on ultracold atoms.
The Bigelow BEC lab's work presently revolves around vortices and complex spin textures in spinor BECs. We engineer the phase and amplitude of each magnetic spin state of a Bose-Einstein condensate using a coherent two-photon stimulated Raman interaction. This allows us to create complex non-equilibrium spatially-dependent spin textures with specific spin and orbital (vortex) angular momenta. Depending on the choice of spin texture, we can study a wide range of phenomena, each connecting to a different field of physics. Since we are using Rubidium-87, we can create both spin-1 and spin-2 spin textures, as well as pseudo-spin systems. Our work both furthers fundamental understanding of spin-dependent symmetries and light-matter interactions, as well as extends applications of ultracold atomic physics to metrology and quantum information.
We are also part of NASA's Consortium for Ultracold Atoms in Space at the Cold Atom Laboratory (CAL) on the International Space Station (ISS) in collaboration with the Jet Propulsion Laboratory (JPL). We are excited to help BEC physics boldly go to new frontiers. Read more here.
Our experiment uses 87-Rb (rubidum), a double magneto-optical trap (MOT) setup, a Ioffe-Prichard magnetic trap, and forced RF evaporative cooling to create a Bose-Einstein condensate of 5,000,000 atoms. We create vortices and spin textures in the BEC using a coherent two-photon stimulated Raman process, which requires microsecond laser pulses, tuned to the correct powers and frequencies to within microwatts and 10 MHz, respectively. We have developed a powerful numerical model to describe this Raman interaction. Our data is collected by absorption imaging, which gives us information about the density distribution of the atomic cloud in space; Stern-Gerlach imaging, which spatially separates the atomic cloud by its spin state; and matter-wave interference, which reveals the spatially-dependent phase of the condensate. Our optical vortices are created using a spiral phase plate from RPC Photonics or a spatial light modulator.
This work has been supported by The National Science Foundation (NSF), The Army Research Office (ARO) of the United States Army Research Laboratory (ARL), The Defense Advanced Research Projects Agency (DARPA) of The United States Department of Defense (DOD), and the NASA-JPL Physical Science Research Program Cold Atom Laboratory (CAL).