On the Singular Spectrum of the Almost Mathieu Operator
Paul B. Wiegmann · Progress of Theoretical Physics Supplement · 1999
I review a recent progress towards solution of the so-called almost Mathieu equation, known also as Harper's equation or Azbel-Hofstadter problem. The spectrum of this equation is known to be a pure singular continuum with a rich hierarchical structure. Few years ago it has been found that the almost Mathieu operator is integrable. An asymptotic solution of this operator becamepossible due analysis the Bethe Ansatz equations.