Probing a Singular Potential with Cold Atoms: A Neutral Atom and a Charged Wire

Abstract

By charging a thin wire we realize a pure attractive 1͞r 2 potential of variable strength for cold neutral atoms. Scattering experiments are performed where the charged wire is placed inside a confined gas of cold lithium atoms. We observe the "falling" of atoms into the 1͞r 2 singularity which so far has been only theoretically discussed in textbooks. [S0031-9007(98)06725-8] PACS numbers: 03.75.Be, 03.65.Nk 0031-9007͞98͞81(4)͞737(5)$15.00

Long-time deviations from exponential decay for inverse-square potentials

“…In addition, it is possible to modify the inner region and implement a potential minimum by a time varying sinusoidal voltage in the high frequency limit [32], or by replacing the wire by a charged optical fiber with blue detuned light propagating along the fiber and the cladding removed [31]. Decay experiments with cold atoms showing exponential laws have been performed [30], and the ability to modify the potential parameters makes the observation and study of the long-time power-law in these systems a realistic prospect.…”

“…Attractive inverse square potentials occur physically as effective radial potentials between a charged wire and a polarizable neutral atom [30], the strength factor being proportional to the square of the linear charge density of the wire and thus controllable [30,31,32]. Combined with a repulsive centrifugal term, an arbitrary α/r 2 potential may be implemented.…”

Spontaneous emission of an atom placed near a nanobelt of elliptical cross section

“…This is because the charged wires were employed successfully in order to control the atomic motion [12,13]. The cylindrical geometry is also important for the investigation of fluorescence of substances in submicron capillaries [14,15].…”

Material dependence of the wire-particle Casimir interaction

“…In the plane-particle geometry this force is known as the Casimir-Polder (CP) interaction [21]. Our study of the wire-particle case is motivated by theories [22] and experiments [23,24] on the two-dimensional quantum scattering of neutral atoms or molecules at wires or nanotubes. In an early work, the interaction between a filament and an isotropic atom has been studied for perfectly and nonperfectly conducting metals [25].…”