We use free probability techniques to compute spectra and Brown measures of some non-hermitian operators in finite von Neumann algebras. Examples include where uₙ and are the generators of ℤₙ and ℤ respectively, in the free product ℤₙ*ℤ, or elliptic elements of the form where and are free semicircular elements of variance α and β.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm90-2-3, author = {Philippe Biane and Franz Lehner}, title = {Computation of some examples of Brown's spectral measure in free probability}, journal = {Colloquium Mathematicae}, volume = {89}, year = {2001}, pages = {181-211}, zbl = {0988.22004}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm90-2-3} }
Philippe Biane; Franz Lehner. Computation of some examples of Brown's spectral measure in free probability. Colloquium Mathematicae, Tome 89 (2001) pp. 181-211. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm90-2-3/