There is a pressing need for robust and straightforward methods to create potentials for trapping Bose-Einstein condensates which are simultaneously dynamic, fully arbitrary, and sufficiently stable to not heat the ultracold gas. We show here how to accomplish these goals, using a rapidly-moving laser beam that "paints" a timeaveraged optical dipole potential in which we create BECs in a variety of geometries, including toroids, ring lattices, and square lattices. Matter wave interference patterns confirm that the trapped gas is a condensate. As a simple illustration of dynamics, we show that the technique can transform a toroidal condensate into a ring lattice and back into a toroid. The technique is general and should work with any sufficiently polarizable low-energy particles.

We have studied the deflection of ground-state sodium atoms passing through a micron-sized parallel-plate cavity by measuring the intensity of a sodium atomic beam transmitted through the cavity as a function of cavity plate separation. This experiment provides clear evidence for the existence of the Casimir-Polder force, which is due to modification of the ground-state Lamb shift in the confined space of a cavity. Our results confirm the magnitude of the force and the distance dependence predicted by quantum electrodynamics. PACS numbers: 42.50.Wm, 32.70Jz, 42.50.Lc Physicists have long been intrigued by the idea that the electromagnetic vacuum interacts with charged particles to produce observable effects. The first experimental verification of this idea was the discovery [1] that the 251/2 and 2P\/2 states of hydrogen are not degenerate. Crudely speaking, the degeneracy is split by the ac Stark effect due to the interaction with the vacuum. Energy shifts of this type are now well established and are generally known as Lamb shifts. The vacuum field in the vicinity of a conducting plate is different from that of free space. In particular, at a distance L from the plate, the spatial distribution, polarization, and spectral density of the vacuum field are substantially altered for frequencies below ~~c/L because of the boundary conditions imposed by the plate. The first discussion of a physical effect due to this modification of the vacuum dates back to 1948 and the seminal work of Casimir [2]. Casimir and Polder [3] discussed the interaction of a neutral atom with a plane conducting plate and showed that the modified vacuum gives rise to a spatially varying Lamb shift whose gradient corresponds to an attractive long-range force. Similar long-range forces are found between any pair of neutral objects, the most famous example being perhaps the Casimir force between two conducting plates. We refer to any such force on an isolated atom as a Casimir-Polder force.Although some quantitative measurements exist on the long-range forces between macroscopic dielectrics [4], the Casimir force has been studied only qualitatively [5], and the Casimir-Polder interaction has eluded detection altogether [6]. Recent experiments on the Rydberg states of helium [7] have yielded precise measurements of the long-range interaction between the Rydberg electron and the He + core, but have not yet reached the point of testing the Casimir-Polder interaction [8], known in that system as K r 'et. In the experiment reported here we have probed the vacuum field in a parallel-plate cavity using a beam of ground-state sodium atoms. Since the vacuum field varies with position, the atoms experience a Casimir-Polder force which pushes them towards the cavity walls. We have used the deflection of the beam to demonstrate the existence of this force and to confirm quantitatively the strength predicted by quantum electrodynamics.For a spherical ground-state atom (3s sodium) between parallel ideal mirrors, the position-dependent atom-cavity interacti...

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor.

High precision measurements of the ground state hyperfine structure interval of muonium and of the muon magnetic moment

We present a general discussion of the techniques of destabilizing dark states in laser-driven atoms with either a magnetic field or modulated laser polarization. We show that the photon scattering rate is maximized at a particular evolution rate of the dark state. We also find that the atomic resonance curve is significantly broadened when the evolution rate is far from this optimum value. These results are illustrated with detailed examples of destabilizing dark states in some commonlytrapped ions and supported by insights derived from numerical calculations and simple theoretical models.PACS numbers: 32.60.+i 42.50.Hz

A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.

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A versatile miniature de Broglie waveguide is formed by two parallel current-carrying wires in the presence of a uniform bias field. We derive a variety of analytical expressions to describe the guide and present a quantum theory to show that it offers a remarkable range of possibilities for atom manipulation on the submicron scale. These include controlled and coherent splitting of the wave function as well as cooling, trapping, and guiding. In particular, we discuss a novel microscopic atom interferometer with the potential to be exceedingly sensitive.