2. Solving the linear Schrödinger equation
We start by considering the initial value problem for the linear Schrödinger equation on
\mathbb{R}^n,
\left\{\begin{aligned}i∂_t u(t, x) &= Δ u \\ u(0, x) &= u₀.\end{aligned}\right.
We want to prove that for sufficiently regular u₀ there exists a unique solution u solving
the initial value problem and u has some regularity.