Integrable quantum impurity models

Anastasia Doikou

Hans-Peter Eckle

Anastasia Doikou

Jian Wang, Yusong Cao, Yi Qiao +2 more

We propose an integrable spin-1 chain with a magnetic impurity whose spin is 1/2.The integrability of the model is based on an operator solution of the associated reflection equation.Due to the existence of the impurity, the SU(3) symmetry of the bulk is broken.By using the nested algebraic Bethe ansatz, we obtain the exact solution of the system.The eigenvalues, eigenstates, and Bethe ansatz equations are given explicitly.The method provided in this paper can be generalized to other high-rank quantum integrable systems with magnetic impurities where the spins of the bulk and of impurities are different.

Johan Nilsson, Hans-Peter Eckle, Henrik Johannesson

We consider an integrable model of a one-dimensional mesoscopic ring, with the conduction electrons coupled by a spin exchange to a magnetic impurity. A symmetry analysis based on a Bethe ansatz solution of the model reveals that the current is insensitive to the presence of the impurity. We argue that this is true for any integrable impurity-electron interaction, independent of the choice of physical parameters or couplings. We propose a simple physical picture of how the persistent current gets protected by integrability.

Sergey Bravyi, David Gosset