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Unstable equilibrium in semi-classical regime. I: Microlocal concentration. (Équilibre instable en régime semi-classique. I: Concentration microcale.) (French) Zbl 0819.35116
The authors are interested in the study of the eigenfunctions of the Schrödinger operator in dimension 1 \[ \Biggl( - {{h^ 2} \over 2} {{d^ 2} \over {dx^ 2}}+ V(x) \Biggr) \varphi(x)= E(h) \varphi(x), \] where \(V\) is a \(C^ \infty\) potential, \(V(x)= -x^ 2/2+ o(x^ 2)\) in a neighborhood of 0 and \(\liminf_{| x| \to\infty} V(x)> 0\), \(h\) tends to 0 (semiclassical limit), \(E(h)\) tends to 0 as \(h\) tends to 0.
They analyze how these eigenfunctions are concentrated near the point \(x=0\). As a corollary, they obtain the existence of eigenfunctions of the Laplacian of a revolution surface with \(-1\) curvature which are concentrated on an unstable geodesic.
Reviewer: B.Helffer (Paris)

35Q40 PDEs in connection with quantum mechanics
35P10 Completeness of eigenfunctions and eigenfunction expansions in context of PDEs
81Q10 Selfadjoint operator theory in quantum theory, including spectral analysis