Harry Potter fans rejoice! We may be closer to getting our hands on an invisibility cloak than one would think. US patent 20080165442 A1 is for the system, method and apparatus for cloaking - or in our minds, the invention of the Harry Potter invisibility cloak. Amazing.
According to the patent abstract, "an object to be cloaked is disposed such that the cloaking apparatus is between the object and an observer. The appearance of the object is altered and, in the limit, the object cannot be observed, and the background appears unobstructed." For those of you wondering, all this time since the series has been released, what mystical material Harry's cloak could be fashioned from, this patent answers your questions: "The cloak is formed of a metamaterial where the properties of the metamaterial are varied as a function of distance from the cloak interfaces, and the permittivity is less than unity. The metamaterial may be fabricated as a composite material having a dielectric component and inclusions of particles of sub-wavelength size, so as to have a permeability substantially equal to unity." Clearly not a standard fabric any muggle could buy at Joanne Fabrics, to say the least.
The invention of the Harry Potter invisibility cloak is claimed by Wenshan Cai, Vladimir M. Shalaev, Uday K. Chettiar and Alexander V. Kildishev. Their patent was published in 2008 and they have yet to make the invention available to the public. We wonder if they've made a deal with J.K. Rowling herself to keep it out of the public's hands. (After all, you never know who may be a death eater out there.)
In reality, this patent has research backing from the United States Army with the potential to decrease scattering from an object contained within it while reducing the shadow so that the combination of the cloak and the object contained resemble free space. The patent background states "the effect is generally acknowledged to be imperfect, and the object may appear in a distorted or attenuated form, or the background obscured by the object may be distorted or partially obscured." Less magical in our world, sadly, but still a brilliant invention nonetheless.
Fun Fact: Even the Wizarding World has their own version of the USPTO. In Harry Potter, the Ministry of Magic has the "Ludicrous Patents Office" as part of the Department of Magical Games and Sports. We still don't know exactly the extent of what this department handles so we will leave the possibilities to your imagination.