Since the start of the SimUcQuam project, we have characterized and theoretically modeled the internal structure of charge carriers in different types of doped quantum antiferromagnets. Moreover, we have made significant progress in understanding and characterizing new pairing mechanisms that may arise in these systems, as a direct result of the rich internal structure of the charge carriers. A particular highlight of our research includes the prediction of strong pairing, mediated by strings, in mixed-dimensional antiferromagnets. In a collaboration with the experimental group of Prof. Immanuel Bloch, this has led to the first-ever direct observation of paired dopants in a cold atom quantum simulator. We have further proposed in a series of publications that the pairing mechanism we put forward may underly high-temperature superconductivity recently observed in bilayer niceklates under pressure.
We have then applied our results and insights to the long-standing problem of high-temperature superconductivity in the cuprate compounds, which led us to the formulation of the so-called Feshbach hypothesis of high-Tc. Namely, we propose that the unusually high superconducting temperatures in the cuprates may be a result of near-resonant interactions between fermionic charge carriers with an internal structure, mediated by tightly string-bound pairs of dopants. We have shown that this hypothesis is able to explain some of the key properties of the cuprate superconductors.
Maybe even more importantly, we then discovered that the same hypothesis may apply to the newly discovered bilayer nickelate superconductors: Thereby our theoretical mechanism is able to provide a unifying explanation how superconductivity arises at high temperatures in these seemingly distinct material classes.
In parallel, we have made significant advances in understanding how various collective many-body phases of matter arise in strongly correlated fermions with antiferromagnetic interactions. In another collaboration with the experimental group of Prof. Immanuel Bloch we have discovered the formation of individual stripes, involving correlated structures of multiple dopants, in an extended mixed-dimensional Hubbard model, at relatively high temperatures. To formulate effective theories of such collective phenomena, we have developed lattice gauge theory descriptions and quantum simulation protocols for the latter.
