Atom microtraps based on near-field Fresnel diffraction

We propose and present a quantitative analysis of neutral atom microtraps based on optical near fields produced by the diffraction of a laser wave on small apertures in a thin screen. We show that near-field atom microtraps are capable of storing atoms in micron-sized regions, with estimated trap lifetimes of about $1\mathrm{s}$, when using a moderate laser intensity of about $10\mathrm{W}∕{\mathrm{cm}}^2$. The depth of the proposed Fresnel atom microtraps is about $0.1\mathrm{mK}$. An array of such atom microtraps could have applications to site-selective manipulation of cold atoms.

Figure 1

(Color online) (a) An array of atom microtraps produced by diffracted optical near fields. (b) Schematic of a single microtrap formed by a circular aperture of radius $a$. $E_1$ represents the incoming light field and $E_2$ the diffracted near field.

Figure 2

Atom potential in a Fresnel atom microtrap as a function of transverse coordinates for radius $a=1.5\lambda$ $(ka=9.4)$, at distances above the aperture $z=0.5a,1a,5a$.

Figure 3

(Color online) Atom potential of the Fresnel atom microtrap as a function of the coordinates $z$ and $\rho$ for $a=1.5\lambda$.