Inverse Problem for Harmonic Oscillator Perturbed by Potential, Characterization

Abstract

Consider the perturbed harmonic oscillator Ty=-y’’+x²y+q(x)y in L²(ℝ), where the real potential q belongs to the Hilbert space H={q’, xq∈ L²(ℝ)}. The spectrum of T is an increasing sequence of simple eigenvalues λ _n (q)=1+2n+μ _n , n ≥ 0, such that μ _n → 0 as n→∞. Let ψ _n (x,q) be the corresponding eigenfunctions. Define the norming constants ν _n (q)=lim _x ↑∞log |ψ _n (x,q)/ψ _n (-x,q)|. We show that for some real Hilbert space and some subspace Furthermore, the mapping ψ:q↦ψ(q)=({λ _n (q)}₀^∞, {ν _n (q)}₀^∞) is a real analytic isomorphism between H and is the set of all strictly increasing sequences s={s _n }₀^∞ such that The proof is based on nonlinear functional analysis combined with sharp asymptotics of spectral data in the high energy limit for complex potentials. We use ideas from the analysis of the inverse problem for the operator -y”py, p∈ L²(0,1), with Dirichlet boundary conditions on the unit interval. There is no literature about the spaces We obtain their basic properties, using their representation as spaces of analytic functions in the disk.