Publications

 1996-2000

• Stability of Bose Condensed Atomic Li-7 [Phys. Rev. A 54, 5055-5066 (1996)].
• Renormalization Group Theory of the Three-Dimensional Dilute Bose Gas [Phys. Rev. A 54, 5085-5103 (1996)].
• Theory of Interacting Quantum Gases [J. Res. Natl. Inst. Stand. Technol. 101, 443-455 (1996)].
• Initial Stages of Bose-Einstein Condensation [Phys. Rev. Lett. 78, 768-771 (1997)].
• Collective Excitations, NMR, and Phase Transitions in Skyrme Crystals [Phys. Rev. Lett. 78, 4825-4828 (1997)].
• Variational Approach to the Dilute Bose Gas [Phys. Rev. A 55, 498-512 (1997)].
• Critical Temperature of a Trapped Bose Gas: Mean-Field Theory and Fluctuations [Phys. Rev. A 56, 2041-2045 (1997)].
• The Superfluid State of Atomic Li-6 in a Magnetic Trap [Phys. Rev. A 56, 4864-4878 (1997)].
• Collective Modes in Supersolid He-4 [Phys. Rev. B 56, 14631-14644 (1997)].
• Macroscopic Quantum Tunneling of a Bose Condensate [J. Stat. Phys. 87, 1353-1366 (1997)].
• Growth and Collapse of a Bose Condensate with Attractive Interactions [Phys. Rev. Lett. 80, 2031-2034 (1998)].
• Microscopic Treatment of Binary Interactions in the Non-Equilibrium Dynamics of Partially Bose-Condensed Trapped Gases [Phys. Rev. A 57, 1230-1247 (1998)].
• Elastic and Inelastic Collisions of Li-6 in Magnetic and Optical Traps [Phys. Rev. A 57, 1497-1500 (1998)].
• Condensed Matter Physics with Trapped Atomic Fermi Gases [Lecture at International School of Physics "Enrico Fermi", Varenna (1998)].
• Quantum Kinetic Theory of Trapped Atomic Gases [Lecture at NATO Advanced Study Institute, Leiden (1998)]. You can also listen to my talk on this subject presented during the 1999 JILA Workshop on Bose-Einstein Condensation and Degenerate Fermi Gases.
• Cooper Pair Formation in Trapped Atomic Fermi Gases [Phys. Rev. A 59, 1556-1561 (1999)]. Marianne Houbiers gave a talk on this topic during the 1998 Conference on Bose-Einstein Condensation at the ITP in Santa Barbara.
• Collisionless Modes of a Trapped Bose Gas [Phys. Rev. A 60, 3973-3981 (1999)]. Michiel Bijlsma gave a preliminary talk about our progress with this paper also during the 1998 Conference on Bose-Einstein Condensation at the ITP in Santa Barbara.
• Phonon Exchange in Dilute Fermi-Bose Mixtures: Tailoring the Fermi-Fermi Interaction [Phys. Rev. A 61, 053601 (1999)].
• Coherent versus Incoherent Dynamics during Bose-Einstein Condensation in Atomic Gases [J. Low Temp. Phys. 114, 11-108 (1999)].
• Field Theory for Trapped Atomic Gases [Lecture notes for the Les Houches summer school on "Coherent Atomic Matter Waves" (1999)].
• Coherently Scattering Atoms from an Excited Bose-Einstein Condensate [Phys. Rev. A 62, 013605 (2000)].
• Kinetic Theory of Collective Excitations and Damping in Bose-Einstein Condensed Gases [Phys. Rev. A 62, 053602 (2000)].
• Condensate Growth in Trapped Bose Gases [Phys. Rev. A 62, 063609 (2000)].

2001-2005

• Skyrmions in a Ferromagnetic Bose-Einstein Condensate [Nature 411, 918-920 (2001)].
• Explosion of a Collapsing Bose-Einstein condensate [Phys. Rev. Lett. 86, 2204-2207 (2001)].

  

  Above you see a collapsing condensate of rubidium-85 atoms. The collapse is initiated by suddenly changing the interactions from repulsive to attractive, as in the JILA experiment by Elizabeth Donley and collaborators [Nature 412, 295-299 (2001)]. The pictures are made by Rembert Duine and taken 0, 11, 29, and 37 ms after the start of the collapse.
• Monopoles in an Antiferromagnetic Bose-Einstein Condensate [Phys. Rev. Lett. 87, 120407 (2001)].

  

  Usama Al Khawaja has also made an artist impression of the monopole, which is reproduced above.
• Quantum Phases in an Optical Lattice [Phys. Rev. A 63, 053601 (2001)]. A summary of this paper can be found on the following poster made by Dries van Oosten.

  

  An illustration of the difference between the superfluid and (Mott) insulating phases is given in the above figure. See [Nature 415, 25-26 (2002)] for more details.
• Collisional Frequency Shifts of Absorption Lines in an Atomic Hydrogen Gas [Phys. Rev. A 64, 013618 (2001)].
• Skyrmion Physics in Bose-Einstein Ferromagnets [Phys. Rev. A 64, 043612 (2001)].
• Dynamics of Fluctuating Bose-Einstein Condensates [J. Low Temp. Phys. 124, 431-442 (2001)].
• Phase Fluctuations in Atomic Bose Gases [Phys. Rev. Lett. 88, 070407 (2002)].
• Bright Soliton Trains of Trapped Bose-Einstein Condensates [Phys. Rev. Lett. 89, 200404 (2002)].
• Stochastic Dynamics of a Trapped Bose-Einstein Condensate [Phys. Rev. A 65, 013603 (2002)]. A summary of this paper can be found on the following poster made by Rembert Duine.
• Nonlinear Coupling between Scissors Modes of a Bose-Einstein Condensate [Phys. Rev. A 65, 013605 (2002)].
• Low-dimensional Bose Gases [Phys. Rev. A 66, 013615 (2002); Phys. Rev. A 66, 059902(E) (2002)].
• Many-body Aspects of Coherent Atom-Molecule Oscillations [Phys. Rev. Lett. 91, 150405 (2003)].
• Quantum Fluctuations of a Vortex in an Optical Lattice [Phys. Rev. Lett. 91, 240403 (2003)].
• Mott Insulators in an Optical Lattice with High Filling Fractions [Phys. Rev. A 67, 033606 (2003)].
• Dynamics of a Bose-Einstein Condensate near a Feshbach Resonance [Phys. Rev. A 68, 013602 (2003)].
• Excitations of a Bose-Einstein Condensate in a One-Dimensional Optical Lattice [Phys. Rev. A 68, 013610 (2003)].
• Dimensional and Temperature Crossover in Trapped Bose Gases [Phys. Rev. A 68, 043603 (2003)].
• Ultracold Atoms in an Optical Lattice [Phys. Rev. A 68, 043623 (2003)].
• Microscopic Many-Body Theory of Atomic Bose Gases near a Feshbach Resonance [J. Opt. B: Quantum Semiclass. Opt. 5, S212-S218 (2003)].
• Josephson Frequency of Resonantly Coupled Atomic and Molecular Condensates [New J. Phys. 5, 69.1-69.11 (2003)].
• Crossover Temperature of Bose-Einstein Condensation in an Atomic Fermi Gas [Phys. Rev. Lett. 92, 130401 (2004)].

  

  The main result of our poor man's approach is shown in the above figure made by Gianmaria Falco and Jani Martikainen. The figure shows the molecular condensate fraction as a function of magnetic field and temperature for the recent potassium-40 experiment of Cindy Regal and collaborators [Phys. Rev. Lett. 92, 040403 (2004)]. The projection most clearly shows the crossover temperature that turns out to be in good agreement with these JILA experiments.
• Molecular Kondo Resonance in Atomic Fermi Gases [Phys. Rev. Lett. 92, 140402 (2004)].

  

  Above you see an illustration of the bosonic Kondo-resonance wave function made by Rembert Duine.
• Quantum Phase Transition in an Atomic Bose Gas with a Feshbach Resonance [Phys. Rev. Lett. 93, 020405 (2004)]. A summary of this paper can be found on the following poster made by Mathijs Romans.
• Vortex-Line Solitons in a Periodically Modulated Bose Gas [Phys. Rev. Lett. 93, 070402 (2004)].
• Longitudinal Sound Mode of a Bose-Einstein Condensate in an Optical Lattice [Phys. Rev. A 69, 023608 (2004)].
• Quantum Theory of a Vortex Line in an Optical Lattice [Phys. Rev. A 69, 053617 (2004)].
• Noisy Dynamics of a Vortex in a Partially Bose-Einstein Condensed Gas [Phys. Rev. A 69, 053623 (2004)].
• Spontaneous Squeezing of a Vortex in an One-Dimensional Optical Lattice [Phys. Rev. A 70, 013604 (2004)].
• Atom-Molecule Coherence in Bose Gases [Phys. Rep. 396, 115-195 (2004)].
• Quantum Phases in a Resonantly Interacting Boson-Fermion Mixture [Phys. Rev. Lett. 94, 230404 (2005)].
• Ultracold Superstrings in Atomic Boson-Fermion Mixtures [Phys. Rev. Lett. 95, 250401 (2005)].

  

  Our realization of a nonrelativistic superstring corresponds physically to a vortex in an one-dimensional optical lattice that is filled with fermions in its core. This is illustrated in the above figure made by Michiel Snoek. The optical lattice is needed to make the string supersymmetric.
• Dressed Feshbach Molecules in the BEC-BCS Crossover [Phys. Rev. Lett. 95, 260407 (2005)].
• Inelastic Light Scattering from a Mott Insulator [Phys. Rev. A 71, 021601 (2005)].
• Feshbach Resonances in an Optical Lattice [Phys. Rev. A 71, 043604 (2005)]. A summary of this paper can be found on the following poster made by Dennis Dickerscheid.
• Sweeping a Molecular Bose-Einstein Condensate across a Feshbach Resonance [Phys. Rev. A 71, 063603 (2005)].
• Atom-Molecule Theory of Broad Feshbach Resonances [Phys. Rev. A 71, 063614 (2005)].
• Feshbach Molecules in a One-Dimensional Fermi Gas [Phys. Rev. A 72, 053625 (2005)].

2006-2010

• Vortex-Lattice Melting in a One-Dimensional Optical Lattice [Phys. Rev. Lett. 96, 230402 (2006)].
• Deformation of a Trapped Fermi Gas with Unequal Spin Populations [Phys. Rev. Lett. 97, 190407 (2006)].

  

  Above you see an artist impression of the experimentally observed deformations made by Guthrie Partridge.
• Sarma Phase in Trapped Unbalanced Fermi Gases [Phys. Rev. Lett. 97, 210402 (2006)]. A summary of this paper can be found on the following poster made by Koos Gubbels.
• Quasi-Condensate Growth on an Atom Chip [Phys. Rev. A 73, 053603 (2006)].

  

  An illustration of the difference between ultracold collisions in one and three dimensions is given in the above figure. See [Nature 440, 877-878 (2006)] for more details.

• Pairing of a Trapped Resonantly Interacting Fermion Mixture with Unequal Spin Populations [Phys. Rev. A 74, 011602 (2006)].
• Theory of Ultracold Superstrings [Phys. Rev. A 74, 033607 (2006)].
• Theory of Vortex-Lattice Melting in a One-Dimensional Optical Lattice [Phys. Rev. A. 74, 033615 (2006)].
• BEC-BCS Crossover in an Optical Lattice [Phys. Rev. A 74, 033621 (2006)].
• Bogoliubov Theory of Feshbach Molecules in the BEC-BCS Crossover [Phys. Rev. A. 74, 053618 (2006)].
• Dressed Molecules in an Optical Lattice [New J. Phys. 8, 151.1-151.20 (2006)].
• On the Role of Penning Ionization in Photoassociation Spectroscopy [J. Phys. B.: At. Mol. Opt. Phys. 39, S825-S847 (2006)].
• Trapped Fermionic Clouds Distorted from the Trap Shape due to Many-Body Effects [Phys. Rev. Lett. 98, 260406 (2007)].
• Theory for p-Wave Feshbach Molecules [Phys. Rev. Lett. 99, 190406 (2007)].
• Dressed Molecules in Resonantly Interacting Ultracold Atomic Fermi Gases [Phys. Rev. A. 75, 023612 (2007)].
• Renormalization Group Theory for the Imbalanced Fermi Gas [Phys. Rev. Lett. 100, 140407 (2008)]. A summary of this paper can be found on the following poster made by Koos Gubbels.
• Twin Peaks in RF Spectra of Fermi Gases at Unitarity in the Normal Phase [Phys. Rev. A 77, 031601 (2008)].
• Achieving the Neel State in an Optical Lattice [Phys. Rev. A 77, 023623 (2008)]. A summary of this paper can be found on the following poster made by Arnaud Koetsier.

  

  Arnaud Koetsier also made the above animation of the adiabatic cooling procedure studied in the paper.
• Correlation Effects in Ultracold Two-Dimensional Bose Gases [Phys. Rev. A 78, 013634 (2008)]. A summary of this paper can be found on the following poster made by Lih-King Lim.
• Efimov States near a Feshbach Resonance [Phys. Rev. A 78, 030701 (2008)].
• Spin Polarons and Molecules in Strongly Interacting Atomic Fermi Gases [Phys. Rev. A 78, 031602 (2008)].
• Spin Drag in Noncondensed Bose Gases [Phys. Rev. Lett. 103, 170401 (2009)].
• Lifshitz Point in the Phase Diagram of Resonantly Interacting Li-6-K-40 Mixtures [Phys. Rev. Lett. 103, 195301 (2009)]. A summary of this paper can be found on the following poster made by Jildou Baarsma.
• Damping of Superfluid Flow by a Thermal Cloud [Phys. Rev. Lett. 103, 265301 (2009)].
• A strongly interacting Bose gas: Nozieres and Schmitt-Rink theory and beyond [Phys. Rev. A 79, 063609 (2009)].
• Spin Drag in an Ultracold Fermi Gas on the Verge of a Ferromagnetic Instability [Phys. Rev. Lett. 104, 220403 (2010)].
• Spin Drag Hall Effect in a Rotating Bose Mixture [Phys. Rev. Lett. 105, 155301 (2010)].
• The Imbalanced Antiferromagnet in an Optical Lattice [Phys. Rev. A 81, 023628 (2010)].

  

  The above illustration of a meron pair, which plays an important role in the paper, was made by Arnaud Koetsier.
• Population and Mass Imbalance in Atomic Fermi Gases [Phys. Rev. A 82, 013624 (2010)].

2011-2015

Our work has been performed in collaboration with the groups of Usama Al Khawaja, Immanuel Bloch, Georg Bruun, Keith Burnett, Eric Cornell, Peter Denteneer, Jaap Dijkhuis, Rembert Duine, Steve Girvin, Umut Gursoy, Randy Hulet, Allan MacDonald, Chris Pethick, Marco Polini, Nick Proukakis, Subir Sachdev, Joerg Schmiedmayer, Peter van der Straten, Stefan Vandoren, Giovanni Vignale, Jacco Vink, Johnny Vogels, and Eugene Zaremba, with the postdoctoral researchers  Jens Andersen, Behnam Farid, Masud Haque, Jani Martikainen, Pietro Massignan, Erik Plauschinn, Clement Wong, and Shaoyu Yin, and with the graduate students Michel Bijlsma, Marianne Houbiers, Michiel Bijlsma, Dries van Oosten, Gianmaria Falco, Dennis Dickerscheid, Lih-King Lim, Mathijs Romans, Michiel Snoek, Arnaud Koetsier, Koos Gubbels, Jeroen Diederix, Jildou Baarsma, Hedwig van Driel, Marijn Versteegh, Martijn Mink, Rakpong Kittinaradorn, Jogundas Armaitis, and Jasper van Heugten.