Applications of Integrated Magnetic Microtraps

Lithographically fabricated circuit patterns can provide magnetic guides and microtraps for cold neutral atoms. By combining several such structures on the same ceramic substrate, we have realized the first ``atom chips'' that permit complex manipulations of ultracold trapped atoms or de Broglie wavepackets. We show how to design magnetic potentials from simple conductor patterns and we describe an efficient trap loading procedure in detail. Applying the design guide, we describe some new microtrap potentials, including a trap which reaches the Lamb-Dicke regime for rubidium atoms in all three dimensions, and a rotatable Ioffe-Pritchard trap, which we also demonstrate experimentally. Finally, we demonstrate a device allowing independent linear positioning of two atomic clouds which are very tightly confined laterally. This device is well suited for the study of one-dimensional collisions.Comment: 10 pages, 17 figure

Limits to phase resolution in matter wave interferometry

We study the quantum dynamics of a two-mode Bose-Einstein condensate in a time-dependent symmetric double-well potential using analytical and numerical methods. The effects of internal degrees of freedom on the visibility of interference fringes during a stage of ballistic expansion are investigated varying particle number, nonlinear interaction sign and strength as well as tunneling coupling. Expressions for the phase resolution are derived and the possible enhancement due to squeezing is discussed. In particular, the role of the superfluid - Mott insulator cross-over and its analog for attractive interactions is recognized.Comment: 10 pages, 9 figure

Trapped-Atom-Interferometer in a Magnetic Microtrap

We propose a configuration of a magnetic microtrap which can be used as an interferometer for three-dimensionally trapped atoms. The interferometer is realized via a dynamic splitting potential that transforms from a single well into two separate wells and back. The ports of the interferometer are neighboring vibrational states in the single well potential. We present a one-dimensional model of this interferometer and compute the probability of unwanted vibrational excitations for a realistic magnetic potential. We optimize the speed of the splitting process in order suppress these excitations and conclude that such interferometer device should be feasible with currently available microtrap technique.Comment: 6 pages, 6 figures, submitted to PR

Trapping cold atoms near carbon nanotubes: thermal spin flips and Casimir-Polder potential

We investigate the possibility to trap ultracold atoms near the outside of a metallic carbon nanotube (CN) which we imagine to use as a miniaturized current-carrying wire. We calculate atomic spin flip lifetimes and compare the strength of the Casimir-Polder potential with the magnetic trapping potential. Our analysis indicates that the Casimir-Polder force is the dominant loss mechanism and we compute the minimum distance to the carbon nanotube at which an atom can be trapped.Comment: 8 pages, 3 figure

Eigenvalues of the Radially Symmetric p-Laplacian in Rn

For the p-Laplacian Δpυ = div:(| ∇υ|p−2∇υ), p>1, the eigenvalue problem −Δpυ + q(|x|)|υ|p−2υ = λ|υ|p−2υ in Rn is considered under the assumption of radial symmetry. For a first class of potentials q(r)→∞ as r→∞ at a sufficiently fast rate, the existence of a sequence of eigenvalues λk→∞ if k→∞ is shown with eigenfunctions belonging to Lp(Rn). In the case p=2, this corresponds to Weyl's limit point theory. For a second class of power-like potentials q(r)→−∞ as r→∞ at a sufficiently fast rate, it is shown that, under an additional boundary condition at r=∞, which generalizes the Lagrange bracket, there exists a doubly infinite sequence of eigenvalues λk with λk → ±∞ if k→±∞. In this case, every solution of the initial value problem belongs to Lp(Rn). For p=2, this situation corresponds to Weyl's limit circle theor

Publish or Perish: A Dilemma for Academic Librarians?

This study examines the influence of scholarly requirements on librarians’ ability to earn tenure or continuous employment. After a literature review, the authors present the results of a survey of research, doctoral, and master’s-level institutions. Of the 690 responding institutions, 54.3 percent employ tenure-track librarians. Of these, more than 60 percent require some scholarship and 34.6 percent encourage it. At these 374 institutions, 92.2 percent of librarians who underwent tenure review during a three-year period were approved. The authors summarize survey information on librarians not granted tenure as well as those believed by directors to have resigned to avoid tenure review

Fiber Fabry-Perot cavity with high finesse

We have realized a fiber-based Fabry-Perot cavity with CO2 laser-machined mirrors. It combines very small size, high finesse F>=130000, small waist and mode volume, and good mode matching between the fiber and cavity modes. This combination of features is a major advance for cavity quantum electrodynamics (CQED), as shown in recent CQED experiments with Bose-Einstein condensates enabled by this cavity [Y. Colombe et al., Nature 450, 272 (2007)]. It should also be suitable for a wide range of other applications, including coupling to solid-state emitters, gas detection at the single-particle level, fiber-coupled single-photon sources and high-resolution optical filters with large stopband.Comment: Submitted to New J. Phys