Probing Green's Function Zeros by Co-tunneling through Mott Insulators

TL;DR

This paper proposes a theoretical method to directly probe Green's function zeros in strongly correlated Mott insulators via co-tunneling experiments, revealing many-body correlation effects distinct from free band structures.

Contribution

It introduces an effective Hamiltonian for Green's function zeros and demonstrates how co-tunneling can experimentally access these features in correlated materials.

Findings

Effective Hamiltonian for GFZ derived and validated.

Numerical simulations confirm analytical predictions.

Distinct signatures of many-body correlations identified.

Abstract

Quantum tunneling experiments have provided deep insights into basic excitations occurring as Green's function poles in the realm of complex quantum matter. However, strongly correlated quantum materials also allow for Green's functions zeros (GFZ) that may be seen as an antidote to the familiar poles, and have so far largely eluded direct experimental study. Here, we propose and investigate theoretically how co-tunneling through Mott insulators enables direct access to the shadow band structure of GFZ. In particular, we derive an effective Hamiltonian for the GFZ that is shown to govern the co-tunneling amplitude and reveal fingerprints of many-body correlations clearly distinguishing the GFZ structure from the underlying free Bloch band structure of the system. Our perturbative analytical results are corroborated by numerical data both in the framework of exact diagonalization and matrix product state simulations for a one-dimensional model system consisting of a Su-Schrieffer-Heeger-Hubbard model coupled to two single level quantum dots.