Low-lying quasiparticle excitations in strongly correlated superconductors: An ansatz from BCS quasiparticle excitations? Original Research Article

The question about the existence of Bogoliubovʹs quasiparticles in the BCS wave functions underneath Gutzwillerʹs projection is of importance to strongly correlated systems. We develop a method to examine the two-particle excitations of Gutzwiller-projected BCS wave functions by using the variational Monte Carlo approach. We find that the exact Gutzwiller-projected quasiparticle (GQP) dispersions are quantitatively reproduced by the Gutzwiller-projected Bogoliubov quasiparticles (GBQP) except the regions where d-wave Cooper pairing is strong. We believe GBQP provides a reasonable description to the low-energy excitations in strongly correlated superconducting systems because GBQP becomes more stable than GQP near the antinodes. Our framework offers a route to understand the intimate connection between Gutzwillerʹs projection and d-wave Cooper pairing.