Buildings for Synthesis with Clifford+R
Mark Deaconu, Nihar Gargava, Amolak Ratan Kalra, Michele Mosca, Jon Yard
TL;DR
We address exact synthesis for the qutrit Clifford$+\mathsf{R}$ gate set by connecting circuit synthesis to the geometry of a Bruhat-Tits building for $U_3$ over $\mathbb{Z}[\chi^{-1}]$. The authors construct the building explicitly via lattice chains and Cartan decomposition, and use it to prove arithmeticity of the Clifford$+\mathsf{R}$ gate set in a new way. The main technical result is that the group generated by $H,S,R$ at $p=3$ equals $U_3(\mathbb{Z}[\chi^{-1}])$, and synthesis can be visualized as path traversal on a tree acting on lattice chains. This approach bridges number theory and quantum circuit design, providing both a self-contained Bruhat-Tits framework and potential for efficient exact and approximate synthesis algorithms. The work thus advances understanding of arithmetic gate sets and offers concrete geometric tools for qutrit circuit synthesis.
Abstract
We study the problem of exact synthesis for the Clifford+R gate set and give the explicit structure of the underlying Bruhat-Tits building for this group. In this process, we also give an alternative proof of the arithmetic nature of the Clifford+R gate set.
