Ultracold quantum matter

Abstract:

We report the observation of vortex nucleation in a rotating optical lattice. A Rb87 Bose-Einstein condensate was loaded into a static two-dimensional lattice and the rotation frequency of the lattice was then increased from zero. We studied how vortex nucleation depended on optical lattice depth and rotation frequency. For deep lattices above the chemical potential of the condensate we observed a linear dependence of the number of vortices created with the rotation frequency, even below the thermodynamic critical frequency required for vortex nucleation. At these lattice depths the system formed an array of Josephson-coupled condensates. The effective magnetic field produced by rotation introduced characteristic relative phases between neighboring condensates, such that vortices were observed upon ramping down the lattice depth and recombining the condensates. © 2010 The American Physical Society.

Abstract:

We propose a method of using off-resonant light scattering to measure the temperature of fermionic atoms tightly confined in a two-dimensional optical-lattice potential. We show that fluctuations of the intensity in the far-field diffraction pattern arising from thermal correlations of the atoms can be accurately detected above the shot noise by collecting photons scattered in a forward direction, with the diffraction maxima blocked. The sensitivity of this method of thermometry is enhanced by an additional harmonic trapping potential. © 2009 The American Physical Society.

Abstract:

We propose a method of using off-resonant light scattering to measure the temperature of fermionic atoms tightly confined in a two-dimensional optical-lattice potential. We show that fluctuations of the intensity in the far-field diffraction pattern arising from thermal correlations of the atoms can be accurately detected above the shot noise by collecting photons scattered in a forward direction, with the diffraction maxima blocked. The sensitivity of this method of thermometry is enhanced by an additional harmonic trapping potential.

Abstract:

We demonstrate a novel experimental arrangement which can rotate a 2D optical lattice at frequencies up to several kilohertz. Ultracold atoms in such a rotating lattice can be used for the direct quantum simulation of strongly correlated systems under large effective magnetic fields, allowing investigation of phenomena such as the fractional quantum Hall effect. Our arrangement also allows the periodicity of a 2D optical lattice to be varied dynamically, producing a 2D accordion lattice.