A planar quantum magnetic disk (QMD) with a magnetic storage density of 65 Gbit/in.(2), over two orders of magnitude greater than the state-of-the-art magnetic storage density, has been fabricated. The planar QMD structure consists of single-domain nickel (magnetic) nanopillars uniformly embedded in a SiO2 (nonmagnetic) disk. Electron beam lithography was used to define the QMD bit’s size and location, and reactive ion etching was used to form an SiO2 template. Nickel electroplating was used to selectively deposit nickel into the template openings, and chemical mechanical polishing was used to planarize the surface. The resulting QMD consists of ultrahigh density arrays of single-domain magnetic pillars with a 50 nm diameter and 100 nm period uniformly embedded in 200-nm-thick SiO2 and with a surface roughness of 0.5 nm root mean square. Each single-domain structure has a quantized magnetic moment and acts as a single bit to store one bit of binary information. Furthermore, a method for mass production of QMDs, the nanoimprint technique, is discussed.