Proc. Amer. Math. Soc. 126, 2873-2881 (1998) [DOI: 10.1090/S0002-9939-98-04362-7]
Deforming the Point Spectra of One-Dimensional Dirac Operators
We provide a method of inserting and removing any finite number of prescribed eigenvalues into spectral gaps of a given one-dimensional Dirac operator. This is done in such a way that the original and deformed operator are unitarily equivalent when restricted to the complement of the subspace spanned by the newly inserted eigenvalue. Moreover, the unitary transformation operator which links the original operator to its deformed version is explicitly determined.