  This paper is dedicated to studying the matrix solutions to the cubic
Szeg\H{o} equation, introduced in G\'erard--Grellier (2009) arXiv:0906.4540,
leading to the cubic matrix Szeg\H{o} equation on the torus, \begin{equation*}
  i \partial_t U = \Pi_{\geq 0} \left(U U ^* U \right), \quad \Pi_{\geq 0}:
\sum_{n\in \mathbb{Z}}\hat{U}(n) e^{inx} \mapsto \sum_{n \geq 0} \hat{U}(n)
e^{inx}.
  \end{equation*}This equation enjoys a two-Lax-pair structure, which allow
every solution to be expressed explicitly in terms of the initial datum and the
time $t \in \mathbb{R}$.
