Achieving ultrahigh-temperature superfluidity in atomic Fermi gases by suppressing pairing fluctuations

Achieving room-temperature superconductivity has been a long-sought goal of both the physics community and the industry. The superfluid transition temperature Tc of a Fermi system initially increases with increasing pairing strength between fermions following the mean-field prediction of the Bardeen-Cooper-Schrieffer (BCS) theory, and is then suppressed by pairing fluctuations as the strength increases further. This prevents Tc from becoming high. In this talk, I will propose a novel mechanism for suppressing pairing fluctuations and thus enabling an ultrahigh Tc at moderately strong attraction, using the synergy between population imbalance and momentum space confinement induced by the periodicity of lattice systems.We show that this can be realized in strongly interacting two-component Fermi gases, as a prototype for superconductors, with an on-site attractive interaction in a three-dimensional optical lattice. Due to the momentum space confinement, a strong Pauli exclusion between paired and excessive majority fermions effectively pushes up the pair energy and suppresses finite-momentum pairing fluctuations, leading to an enhanced Tc at strong pairing interactions with a proper population imbalance. This proposed mechanism opens new avenues for experimental realization of possible room temperature superconductivity, offering transformative insights into the fundamental nature of quantum matter and its potential applications.