Probing Green's Function Zeros by Cotunneling through Mott Insulators.

Area of Science:

• Condensed matter physics
• Quantum mechanics
• Materials science

Background:

• Quantum tunneling experiments reveal excitations as Green's function poles.
• Green's function zeros (GFZs) are less understood but crucial in quantum materials.
• GFZs have largely eluded direct experimental study.

Purpose of the Study:

• To theoretically investigate cotunneling through Mott insulators for accessing GFZs.
• To reveal the shadow band structure associated with GFZs.
• To distinguish GFZ structure from Bloch band structure using many-body correlations.

Main Methods:

• Derivation of an effective Hamiltonian for GFZs.
• Analysis of cotunneling amplitude governed by the GFZ Hamiltonian.
• Perturbative analytical calculations.
• Numerical simulations using exact diagonalization and matrix product states.

Main Results:

• Cotunneling provides direct access to the shadow band structure of GFZs.
• The derived GFZ Hamiltonian governs cotunneling amplitude.
• Fingerprints of many-body correlations are identified, distinguishing GFZs from Bloch bands.
• One-dimensional Su-Schrieffer-Heeger-Hubbard model coupled to quantum dots used as a test system.

Conclusions:

• Cotunneling is a viable theoretical probe for studying GFZs in quantum materials.
• The shadow band structure provides unique insights into strongly correlated systems.
• This work opens avenues for experimental investigation of GFZs.