Superstripes

Superstripes is a generic name for a phase with spatial broken symmetry that favors the onset of superconducting or superfluid quantum order.

This scenario emerged in the 1990s when non-homogeneous metallic heterostructures at the atomic limit with a broken spatial symmetry have been found to favor superconductivity.

The problem remained elusive for many years since these materials have generally a very complex structure making unuseful theoretical modelling for a homogeneous system.

The advances in experimental investigation on local lattice fluctuations have driven the community to the conclusion that it is a problem of quantum physics in complex matter.

Direct evidence for shape resonances in superstripes matter is provided by the anomalous variation of the isotope effect on the critical temperature by tuning the chemical potential.

The MIT group exposed a Bose-Einstein condensate in a double-well potential to light beams that created an effective spin-orbit coupling.

The interference between the atoms on the two spin-orbit coupled lattice sites gave rise to a density modulation that establishes a stripe phase with supersolid properties.

Crystal structure of the tetragonal (superconductive) phase of La 2 CuO 4 : top view (top-right) and CuO 6 octahedron (bottom-right). [ 7 ]
Dispersion relations of a spin–orbit coupled system for different coupling strengths. Box A has no coupling. The dispersion relation shows 2 shifted free space dispersion relations. Box B shows how the gap at k=0 opens for weak coupling. Box C shows the strong coupling limit where the double degenerate minima in the first band merge into a single ground state at k=0.