  The presence of two components in the electron fluid of high temperature
superconductors and the complex charge and lattice inhomogeneity have been the
hot topics of the international conference of the superstripes series,
Superstripes 2015, held in Ischia in 2015. The debate on the mechanisms for
reaching room temperature superconductivity has been boosted by the discovery
of superconductivity with the highest critical temperature in pressurized
sulfur hydride. Different complex electronic and structural landscapes showing
up in superconductors which resist to the decoherence effects of high
temperature has been discussed. While low temperature superconductors described
by the BCS approximation are made of a single condensate in the weak coupling
the high temperature superconductors are made of coexisting multiple
condensates, in different spots of the k-space and the real space, some in the
BCS-BEC crossover regime and others in the BCS regime. The role of shape
resonance in the exchange interaction between these different condensates, like
the Fano-Feshbach Resonance in ultracold gasses, is emerging as a key term for
high temperature superconductivity.

Superconductivity