A symplectic approach to Schrödinger equations in the infinite-dimensional unbounded setting
Javier de Lucas, Julia Lange, Xavier Rivas
TL;DR
This work develops a rigorous symplectic-geometric treatment of $t$-dependent Schrödinger equations on separable Hilbert spaces driven by unbounded self-adjoint Hamiltonians with a common domain of analytic vectors. By encoding quantum dynamics as Hamiltonian flows on normed/Banach manifolds, it clarifies how to handle unbounded observables and constructs a coherent framework using $(oldsymbol{ ext{H}},oldsymbol{ ext{ω}})$ on a domain, with the Schrödinger equation given by $rac{d}{dt}oldsymbol{\psi}=-iH(t)oldsymbol{\psi}$ corresponding to the Hamiltonian vector field of $ frac{1}{2}igra oldsymbol{\psi}ig|H(t)oldsymbol{\psi}igra$. The Marsden--Weinstein reduction is then employed to project these dynamics onto the projective Hilbert space $oldsymbol{ ext{PH}}$, yielding a reduced symplectic form $oldsymbol{ ext{ω}}_oldsymbol{\mu}$ and reduced Hamiltonians $f_eta^{oldsymbol{\\mu}}$, governing the rays that encode physical states. These contributions provide a rigorous bridge between infinite-dimensional quantum mechanics and symplectic reduction, with potential for extending to Hamilton–Jacobi theory and broader reductive techniques in quantum dynamics.
Abstract
By using the theory of analytic vectors and manifolds modelled on normed spaces, we provide a rigorous symplectic differential geometric approach to $t$-dependent Schrödinger equations on separable (possibly infinite-dimensional) Hilbert spaces determined by unbounded $t$-dependent self-adjoint Hamiltonians satisfying a technical condition. As an application, the Marsden--Weinstein reduction procedure is employed to map above-mentioned $t$-dependent Schrödinger equations onto their projective spaces. Other applications of physical and mathematical relevance are also analysed.
