Patent ID: 7521708

Claim:
A magnetic sensing system comprising: a hollow cylindric structure that includes at least three annular layers, said hollow cylindric structure being characterized by a geometric axis, an axial hole, and two opposite ends, each said annular layer lying in a geometric plane that is perpendicular to said geometric axis, said at least three annular layers being at least one annular non-superconductive layer and at least two annular superconductive layers, a first said annular superconductive layer being situated at a first said end, a second said annular superconductive layer being situated at a second said end, said at least three annular layers including at least one annular Josephson junction, each said annular Josephson junction being constituted by two said annular superconductive layers and a said annular non-superconductive layer situated therebetween; a power source for imparting an electrical bias current to said hollow cylindric structure so that said electrical bias current is conducted through said hollow cylindric structure along said geometric axis from said first annular superconductive layer to said second annular superconductive layer, said power source being electrically connected to said first annular superconductive layer, said at least one annular Josephson junction being characterized by an electrical critical current, said electrical critical current being the maximum electrical current across said at least one annular Josephson junction before said at least one annular Josephson junction manifests electrical resistance and an electrical voltage; and a voltage measurement device for measuring a said electrical voltage that is associated with said electrical critical current and with an external magnetic field that is aligned with said geometric axis and extends through said axial hole, said voltage measurement device being electrically connected to said second annular superconductive layer and said power source, the measured said electrical voltage being indicative of the strength of said external magnetic field.