Projected d-wave superconducting state: a fermionic projected entangled pair state study

TL;DR

This paper develops a fermionic projected entangled pair state (fPEPS) approach to model projected d-wave superconducting states, enabling accurate evaluation of physical properties in the thermodynamic limit without approximations.

Contribution

It introduces a novel fPEPS-based method to represent and analyze projected d-wave pairing states, improving the study of strongly correlated superconductors.

Findings

Achieved competitive energies for the doped t-J model.

Demonstrated the effectiveness of the tensor network representation for projected d-wave states.

Provided a new framework for variational tensor network calculations in superconductivity.

Abstract

We investigate the physics of projected d-wave pairing states using their fermionic projected entangled pair state (fPEPS) representation. First, we approximate a d-wave Bardeen-Cooper-Schrieffer state using the Gaussian fPEPS. Next, we translate the resulting state into fPEPS tensors and implement the Gutzwiller projection which removes double occupancy by modifying the local tensor elements. The tensor network representation of the projected d-wave pairing state allows us to evaluate physical quantities in the thermodynamic limit without employing the Gutzwiller approximation. Despite having very few variational parameters, such physically motivated tensor network states are shown to exhibit competitive energies for the doped t-J model. We expect that such construction offers useful initial states and guidance for variational tensor network calculations.