Researchers have discovered that certain disordered superconductors exhibit abrupt phase transitions, a finding that challenges established theories and could have implications for quantum computing.
A study published in Nature by researchers investigating indium oxide films — a highly disordered superconductor — shows that their transition from a superconducting to an insulating state is not gradual, as traditionally assumed, but sudden. This abrupt shift, known as a first-order quantum phase transition, contrasts with the commonly observed continuous, second-order transitions in superconductors.
Key measurements revealed a sharp drop in superfluid stiffness — which is a property that reflects the superconducting state’s ability to resist phase distortions — at a critical level of disorder. Interestingly, the critical temperature of these films, where superconductivity breaks down, no longer depended on the strength of electron pairing but rather on the superfluid stiffness. This behavior aligns with a pseudogap regime, where electron pairs exist but lack the coherence needed for superconductivity.
