Topological Order in the Pseudogap Metal
The copper oxide-based high-temperature superconductors display a mysterious "pseudogap" metal phase at temperatures just above the critical temperature in a regime of low hole density. Extensive experimental and numerical studies have yielded much information on the nature of the electron corrections, but a fundamental theoretical understanding has been lacking.
In an article in PNAS, postdoc Mathias Scheurer, grad student Shubhayu Chatterjee, Prof. Subir Sachdev, and colleagues from University of Paris-Saclay show that a theory of a metal with topological order and emergent gauge fields can model much of the numerical data. This study opens up a route to a deeper understanding of the long-range quantum entanglement in these superconductors and to the direct detection of the topological characteristics of the many-body quantum state.
*See M.S. Scheurer, S. Chatterjee, W. Wu, M. Ferrero, A. and S. Sachdev, "Topological order in the pseudogap metal," PNAS (2018) https://doi.org/10.1073/pnas.1720580115.