Superconductivity

Superconductivity is another example of symmetry breaking. Superconductivity is a property of certain materials, which lose all electrical resistance at sufficiently low temperature, meaning that, once switched on, electric currents would never die. It turns out that the explanation of this phenomenon is based on the same potential as the Higgs potential or the ridged bowl. The analog of the Higgs field in this case is a complex field \rho with potential such that |\rho|=A at the minimum. The current in a circular superconductor comes in discrete units, or quanta, which can be thought of as windings of the phase, of \rho , at the bottom of the circular potential (Fig. 35 ): \rho=A\cdot exp(i\phi) , and \phi winds around the “Mexican hat” potential n times as we go around the circular loop parameterized by the angle \theta \phi=n\theta . As it turns out the current I\propto n . Therefore the strength of the current is directly proportional to the number of windings of the phase of \rho .