Corner transfer matrices for 2D strongly coupled many-body Floquet systems

TL;DR

This paper introduces a numerically exact, renormalizable method based on Baxter's corner transfer matrices to analyze the level density of 2D Floquet systems, revealing complex parameter-dependent behaviors and potential phase transitions.

Contribution

It develops a novel renormalizable approach using corner transfer matrices for 2D Floquet systems, enabling large-scale computations and uncovering new phase transition insights.

Findings

Density of Floquet quasi-energy spectrum tends to a flat function in the thermodynamic limit.

Decay rates of Fourier coefficients show rich, non-trivial parameter dependence.

Method's renormalizability depends on the effective rank of corner transfer matrices.

Abstract

We develop, based on Baxter's corner transfer matrices, a renormalizable numerically exact method for computation of the level density of the quasi-energy spectra of two-dimensional (2D) locally interacting many-body Floquet systems. We demonstrate its functionality exemplified by the kicked 2D quantum Ising model. Using the method, we are able to treat the system of arbitrarily large finite size (for example 10000 x 10000 lattice). We clearly demonstrate that the density of Floquet quasi-energy spectrum tends to a flat function in the thermodynamic limit for generic values of model parameters. However, contrary to the prediction of random matrices of the circular orthogonal ensemble, the decay rates of the Fourier coefficients of the Floquet level density exhibit rich and non-trivial dependence on the system's parameters. Remarkably, we find that the method is renormalizable and gives thermodynamically convergent results only in certain regions of the parameter space where the corner transfer matrices have effectively a finite rank for any system size. In the complementary regions, the corner transfer matrices effectively become of full rank and the method becomes non-renormalizable. This may indicate an interesting phase transition from an area- to volume- law of entanglement in the thermodynamic state of a Floquet system.