Towards a rigorous derivation of the cubic NLSE in dimension one. (English) Zbl 1069.35082
Summary: We consider a system of \(N\) particles in dimension one, interacting through a zero-range repulsive potential whose strength is proportional to \(N^{-1}\). We construct the finite and the infinite Schrödinger hierarchies for the reduced density matrices of subsystems with \(n\) particles. We show that the solution of the finite hierarchy converges in a suitable sense to a solution of the infinite one. Besides, the infinite hierarchy is solved by a factorized state, built as a tensor product of many identical one-particle wave functions which fulfill the cubic nonlinear Schrödinger equation. Therefore, choosing a factorized initial datum and assuming propagation of chaos, we provide a derivation for the cubic NLSE. The result, achieved with operator-analysis techniques, can be considered as a first step towards a rigorous deduction of the Gross-Pitaevskii equation in dimension one. The problem of proving propagation of chaos is left untouched.
MSC:
35Q55 | NLS equations (nonlinear Schrödinger equations) |
81T10 | Model quantum field theories |
82C22 | Interacting particle systems in time-dependent statistical mechanics |
37K10 | Completely integrable infinite-dimensional Hamiltonian and Lagrangian systems, integration methods, integrability tests, integrable hierarchies (KdV, KP, Toda, etc.) |