Floquet topological superconductivity induced by chiral many-body interaction

Floquet theory allows the design of quantum phases of matter with exotic properties via non-trivial modulation of the effective static Hamiltonian by time-periodic driving.

In particular, by controlling the band topology, a variety of topological phases can be realized dynamically, including Chern insulators.

While extending this idea to topological superconductivity is an important application, the same mechanism cannot be straightforwardly applied to typical superconductors.

The gap function is not directly coupled to the electromagnetic field, making it difficult to modulate the pairing symmetry and induce topological phase transitions.

In this study, we find that this difficulty can be overcome by taking into account correlation effects.

Namely, we show that the d-wave superconductivity of the doped Hubbard model can be dynamically transformed to topological d+id superconductivity by irradiation of circularly polarized light.

To this end, we derive the Floquet t-J model by combining Floquet theory and the Schrieffer-Wolff transformation.

The resulting Hamiltonian has emergent chiral many-body interactions with broken time-reversal symmetry, with which we can actually modulate the pairing symmetry. We demonstrate the topological phase transition within the framework of Gutzwiller approximation.