  Ultracold atom-traps on a chip enhances the practical application of atom
traps in quantum information processing, sensing, and metrology. Plasmon
mediated near-field optical potentials are promising for trapping atoms. The
combination of plasmonic nanostructures and ultracold atoms has the potential
to create a two dimensional array of neutral atoms with lattice spacing smaller
than that of lattices created from interfering light fields -- the optical
lattices. We report the design, fabrication and characterization of a
nano-scale array of near-field optical traps for neutral atoms using plasmonic
nanostructures. The building block of the array is a metallic nano-disc
fabricated on the surface of an ITO-coated glass substrate. We numerically
simulate the electromagnetic field-distribution using Finite Difference Time
Domain method around the nanodisc, and calculate the intensity, optical
potential and the dipole force for $^{87}$Rb atoms. The optical near-field
generated from the fabricated nanostructures is experimentally characterized by
using Near-field Scanning Optical Microscopy. We find that the optical
potential and dipole force has all the desired characteristics to trap cold
atoms when a blue-detuned light-field is used to excite the nanostructures.
This trap can be used for effective trapping and manipulation of isolated atoms
and also for creating a lattice of neutral atoms having sub-optical wavelength
lattice spacing. Near-field measurements are affected by the influence of tip
on the sub-wavelength structure. We present a deconvolution method to extract
the actual near-field profile from the measured data.
