An Inverse Theorem for Partially Symmetric Two-Dimensional Semiclassical Schrödinger Operators

Abstract

We study a two-dimensional semiclassical Schrödinger operator whose potential admits one reflection symmetry. Under a rational independence assumption on the harmonic frequencies and a nonvanishing condition \(a_{30}\ne0\), we show that the first two layers of the quantum Birkhoff normal form, together with the sign of \(a_{30}\) and the transverse data \(\{a_{1,2k}\}_{k\ge1}\), determine the Taylor series of the potential at the bottom of the well. The proof is constructive: the \(\hbar^2\)-layer gives a triangular recursion for odd-degree terms, while the classical layer recovers even-degree terms from their resonant projections.