Controlling correlations of a polaritonic Luttinger liquid by engineered cross-Kerr nonlinearity
Phys. Rev. B 113, 174520 – Published 18 May, 2026
DOI: https://doi.org/10.1103/yjtj-c22v
Abstract
We study correlation properties of polaritons at zero temperature in a multiconnected Jaynes-Cummings lattice on a superconducting circuit quantum electrodynamics platform with engineered cross-Kerr nonlinearity that mimics attractive nearest-neighbor interaction. A multiconnected Jaynes-Cummings lattice is a one-dimensional lattice constructed from alternating qubits and resonators with different left and right couplings. The nearest-neighbor interaction or cross-Kerr coupling is implemented dispersively through ladder-type qutrits between each nearest-neighboring pair of resonator modes. Projecting onto the lower-polaritonic manifold, we derive an extended two-mode (bipartite) Bose-Hubbard-like model featuring on-site and attractive nearest-neighbor interactions. Employing a continuum bosonization approach, we express the Hamiltonian in terms of symmetric and antisymmetric collective modes. In the regime where the sector acquires a finite gap, one can reduce the system to an effective single-component Luttinger liquid model for the sector. The cross-Kerr term reduces the compressibility of the mode, thereby enhancing the corresponding Luttinger parameter , resulting in the slower algebraic decay of single-particle correlations, .