M. L. Chiofalo

Superfluid and Dissipative Dynamics of a Bose-Einstein Condensate in a Periodic Optical Potential

We create Bose-Einstein condensates of 87Rb in a static magnetic trap with a superimposed blue-detuned 1D optical lattice. By displacing the magnetic trap center we are able to control the condensate evolution. We observe a change in the frequency of the center-of-mass oscillation in the harmonic trapping potential, in analogy with an increase in effective mass. For fluid velocities greater than a local speed of sound, we observe the onset of dissipative processes up to full removal of the superfluid component. A parallel simulation study visualizes the dynamics of the Bose-Einstein condensate and accounts for the main features of the observed behavior.

Resonance superfluidity : renormalization of resonance scattering theory

We derive a theory of superfluidity for a dilute Fermi gas that is valid when scattering resonances are present. The treatment of a resonance in many-body atomic physics requires a novel mean-field approach starting from an unconventional microscopic Hamiltonian. The mean-field equations incorporate the microscopic scattering physics, and the solutions to these equations reproduce the energy-dependent scattering properties. This theory describes the high-T/sub c/ behavior of the system, and predicts a value of T/sub c/ that is a significant fraction of the Fermi temperature. It is shown that this mean-field approach does not break down for typical experimental circumstances, even at detunings close to resonance. As an example of the application of our theory, we investigate the feasibility for achieving superfluidity in an ultracold gas of fermionic /sup 6/Li.

Coherent Delocalization of Atomic Wave Packets in Driven Lattice Potentials

Atomic wave packets loaded into a phase-modulated vertical optical-lattice potential exhibit a coherent delocalization dynamics arising from intraband transitions among Wannier-Stark levels. Wannier-Stark intraband transitions are here observed by monitoring the in situ wave-packet extent. By varying the modulation frequency, we find resonances at integer multiples of the Bloch frequency. The resonances show a Fourier-limited width for interrogation times up to 2 s. This can also be used to determine the gravity acceleration with ppm resolution.

Signatures of resonance superfluidity in a quantum Fermi gas

We predict a direct and observable signature of the superfluid phase in a quantum Fermi gas, in a temperature regime already accessible in current experiments. We apply the theory of resonance superfluidity to a gas confined in a harmonic potential and demonstrate that a significant increase in density will be observed in the vicinity of the trap center.

Nature of superfluidity in ultracold Fermi gases near Feshbach resonances

We study the superfluid state of atomic Fermi gases using a BCS-Bose-Einstein-condensation crossover theory. Our approach emphasizes noncondensed fermion pairs which strongly hybridize with their (Feshbach-induced) molecular boson counterparts. These pairs lead to pseudogap effects above

Atomic wave packets in amplitude-modulated vertical optical lattices

{T}_{c}

Evidence of Luttinger-liquid behavior in one-dimensional dipolar quantum gases

and non-BCS characteristics below. We discuss how these effects influence the experimental signatures of superfluidity.

Output from Bose condensates in tunnel arrays: the role of mean-field interactions and of transverse confinement

We report on the realization of dynamical control of transport for ultra-cold 88Sr atoms loaded in an accelerated amplitude-modulated one-dimensional (1D) optical lattice. We show that the behavior of the dynamical system can be viewed as if traveling wave packets were moving in a static lattice whose energy dispersion can be tailored at will in width, amplitude and phase. One basic control operation is a reversible switch between Wannier?Stark localization and driven transport based on coherent tunneling. Performing modulation sequences of this operation within a Loschmidt-echo scheme, we are able to reverse the atomic group velocities at once. We then apply the technique to demonstrate a novel mirror for matter waves working independently of the momentum state. We finally discuss advantages of amplitude over previously reported phase modulation techniques for applications in force measurements at micrometric scales.

Polaron and bipolaron coexistence in high Tc superconductivity

A strongly correlated Luttinger-liquid behavior is found to emerge well beyond the Tonks-Girardeau (TG) regime in a one-dimensional Bose gas with dipolar repulsions at

Generalized quantum hydrodynamics of a trapped dilute Bose gas

T=0