Proposed magnetoelectrostatic ring trap for neutral atoms

Abstract

We propose a trap for confining cold neutral atoms in a microscopic ring using a magnetoelectrostatic potential. The trapping potential is derived from a combination of a repulsive magnetic field from a hard drive atom mirror and the attractive potential produced by a charged disk patterned on the hard drive surface. We calculate a trap frequency of ͓29.7, 42.6, 62.8͔ kHz and a depth of ͓16. Traps are a standard tool for the study and manipulation of cold neutral atoms, allowing the investigation of fundamental quantum dynamics as well as providing a basis for quantum information processing. The manipulation of trapped atoms on "atom chips" allows the implementation of many different atom optics elements for trapping, waveguiding, interferometry, etc. [1,2]. Most atom chips use micronsized current-carrying wires to generate the magnetic trapping fields. We propose to construct a magnetoelectrostatic ring trap, consisting of a hard drive atom mirror that provides a repulsive force on low-field seeking atoms [3] and electric pads that attract polarizable atoms via the Stark effect [4-6]. Schmiedmayer and Hinds and Hughes have proposed a range of such traps, including large-area two-dimensional traps, wire-based waveguides, and quantum-dot-like single state traps. Such traps could be used to construct beam splitters or to implement collisional quantum gates [7]. Here we propose a ring trap for cold neutral atoms constructed from a conducting disk placed above the atom mirror surface, which produces a trap with a deep ring potential around the edge of the disk.Let us first examine the trapping potential from a charged conducting disk above a hard drive atom mirror. The hard drive's sinusoidal pattern of magnetization results in a repulsive potential-for atoms in weak-field seeking states-in the form of a decaying exponential [8]The amplitude depends on the remnant magnetization of the mirror, B 0 , as well as the magnetic sublevel m F and Landé g F -factor of the atomic ground state. The decay length is proportional to the periodicity a of the magnetization pattern.A small externally applied magnetic field perpendicular to the magnetization of the hard disk eliminates zones of zero magnetic field which would allow Majorana spin-flip losses. The atom's low velocity allows the spin adiabatically to follow the magnetic field and thus the trapping potential depends only on the field magnitude.In order to create a trap, the repulsive force from the mirror is balanced by an attractive force due to the dc Stark effect. The atomic potential due to an electric field iswhere we assume that we are working with atoms such as cesium or rubidium which possess only a scalar polarizability in the ground state. A charged conducting disk creates high electric fields near its edge, resulting in a strong shortrange attractive potential. The mirror is made out of an etched hard drive whose aluminum substrate is grounded. The boundary conditions consist of a ground at the mirror surface, and a constant potential on the surface of the thi...

A smooth, holographically generated ring trap for the investigation of superfluidity in ultracold atoms

“…There have been numerous alternative proposals for toroidal atom traps using magnetic fields with [6] or without rf-dressing [7], electrostatic fields [8], time-averaged optical fields [9] or Laguerre-Gauss beams [10,11]. An advantage of using optical rather than magnetic potentials is that they are suitable for trapping atoms in any state.…”

Dynamically controlled toroidal and ring-shaped magnetic traps

“…These leaks have been plugged using time orbiting ring traps (TORTs) [9], out-of-plane current carrying wires [10], or stadium-shaped traps reducing the ring of zero to four points [11]. Also electrostatic fields have been proposed as a possible solution for a chip-based trap [12]. For chipbased approaches [12,13,14] the symmetry-breaking potential corrugation caused by lead wires must typically also be addressed.…”

Many-particle dynamics of bosons and fermions in quasi-one-dimensional flat-band lattices

“…There are several ways to produce a toroidal trap for atom condensates [27,[33][34][35][36]. In the case of finite quantum rings made of the Q1D lattices considered, we induce an effective magnetic flux through the ring in order to induce a current.…”