Observation of broken inversion and chiral symmetries in the pseudogap phase in single- and double-layer bismuth-based cuprates

One of the long-standing questions in study high-${T}_{c}$ cuprate superconductors has been understanding nature boundary between strange metal phase and so-called pseudogap phase, which is a precursor to superconductivity. Testing for possible symmetry breaking transition through that boundary, detailed photogalvanic effect along set crystallographic axes BSCCO reveals state with broken inversion chiral symmetries, thus strongly constraining theoretical proposals this phenomenon.