Kondo effect in a non-Hermitian PT-symmetric Anderson model with Rashba spin-orbit coupling

The noninteracting and non-Hermitian, parity-time (PT) symmetric Anderson model exhibits an exceptional point (EP) at a non-Hermitian coupling g = 1, which remains unrenormalized in the presence of interactions [J. A. S. Lourenco et al., Phys. Rev. B 98, 085126 (2018)], where the EP was shown to coincide with the quantum critical point for Kondo destruction. In this work, we consider a quantum dot hybridizing with metallic leads having Rashba spin-orbit coupling (lambda). We show that for a non-Hermitian hybridization, lambda can renormalize the exceptional point even in the noninteracting case, stabilizing PT symmetry beyond g = 1. Through exact diagonalization of a zero-bandwidth, three-site model, we show that the quantum critical point and the exceptional point bifurcate, with the critical point for Kondo destruction at g(c) = 1, and the exceptional coupling being gEP > 1 for all U &NOTEQUexpressionL; 0 and lambda >= 0; lambda =? U/2. On the line lambda = U/2, the critical point and the EP again coincide at g(c) = g(EP )= 1. The full model with finite-bandwidth leads is investigated through the slave-boson approach, using which we show that, in the strong-coupling regime, lambda and interactions cooperate in strongly reducing the critical point associated with Kondo destruction, below the lambda = 0 value.

Automated summary

This study investigates the noninteracting and non-Hermitian, parity-time (PT) symmetric Anderson model, and finds that in the noninteracting case, the exceptional point can be renormalized by the non-Hermitian coupling and Rashba spin-orbit coupling. The relationship between the critical point and the exceptional point varies for different parameter values.