A characterization of Rieffel's deformed algebra as Heisenberg smooth operators

Abstract: Let $\mathcal{C}$ be a unital C$^*$-algebra and $E_n$ be the Hilbert $\mathcal{C}$-module defined as the completion of the $\mathcal{C}$-valued Schwartz function space $\mathcal{S}^\mathcal{C}(\mathbb{R}^n)$ with respect to the norm $|f|2 := \left| \int{\mathbb{R}^n} f(x)^*f(x) \, dx \right|_\mathcal{C}^{1 / 2}$. Also, let $\text{Ad }\mathcal{U}$ be the canonical action of the $(2n + 1)$-dimensional Heisenberg group by conjugation on the algebra of adjointable operators on $E_n$ and let $J$ be a skew-symmetric linear transformation on $\mathbb{R}^n$. We characterize the smooth vectors under $\text{Ad }\mathcal{U}$ which commute with a certain algebra of right multiplication operators $R_h$, with $h \in \mathcal{S}^\mathcal{C}(\mathbb{R}^n)$, where the product is "twisted" with respect to $J$ according to a deformation quantization procedure introduced by M.A. Rieffel. More precisely, we establish that they coincide with the corresponding algebra of left multiplication operators, as conjectured by Rieffel.