  We look back on the turning point of the concept of individual electron
carrier and paired electrons carrier in superconductivity history, look back on
the magnetic flux quantization interpretation and experiment, reference the new
discovery of new phenomena including the hc/e magnetic flux periodicity and the
scaling law of transition temperature of superconducting thin films. The
conclusion is: In a circuit including only one electron, the magnetic flux
period is hc/e in general, but hc/(2e) in the first step starting with zero
flux. Early experiments had not observed hc/e periodicity because multiple
electrons do each first step starting with zero flux. According to the new
experimental explanation, the theory of individual electron carrier is
proposed. It integrates with the energy band theory and the Hubbard model. In
the frame of energy band theory and electron correlation, we do not add Cooper
pair for the carrier, we can use the energy band theory to explain the
phenomenon of superconductivity. It needs the Hubbard model when a
superconductor is a Mott insulator. The theory makes the whole image of
super-insulators, insulators, semiconductors, conductors, superconductors
transition smoothly and continuously. The transition to fractional quantum
Holzer effect is continuous and smooth.
