Unitarity in periodic potentials: A renormalization group analysis

作者：Nikolic Predrag^*

来源：Physical Review B, 2011, 83(6): 064523.

DOI：10.1103/PhysRevB.83.064523

We explore the universal properties of interacting fermionic lattice systems, mostly focusing on the development of pairing correlations from attractive interactions. Using renormalization group, we identify a large number of fixed points and show that they correspond to resonant scattering in multiple channels. Pairing resonances in finite-density band insulators occur between quasiparticles and quasiholes living at different symmetry-related wave vectors in the Brillouin zone. This allows a BCS-BEC crossover interpretation of both Cooper and particle-hole pairing. We show that, in two dimensions, the runaway flows of relevant attractive interactions lead to charged-boson-dominated low-energy dynamics in the insulating states and superfluid transitions in the bosonic mean-field or XY universality classes. Analogous phenomena in higher dimensions are restricted to the strong-coupling limit, while, at weak couplings, the transition is in the pair-breaking BCS class. The models discussed here can be realized with ultracold gases of alkali atoms tuned to a broad Feshbach resonance in an optical lattice, enabling experimental studies of pairing correlations in insulators, especially in their universal regimes. In turn, these simple and tractable models capture the emergence of fluctuation-driven superconducting transitions in fermionic systems, which is of interest in the context of high-temperature superconductors.

• 出版日期2011-2-28