The Equivalence of Schr\"{o}dinger and Heisenberg Pictures in Quantum Cellular Automata

Understand

Quantum cellular automata (QCA) are discrete models of space and time homogeneous quantum field theories (QFTs) and regarded as natural candidates for quantum simulation.

• Description of a QCA over the separable Hilbert space of finite, unbounded configurations (UFC Hilbert space) with unitary state evolution is the {\it Schr\"{o}dinger template}, and over the incomplete infinite tensor product algebra (ITPA) with evolution by algebra automorphism is the {\it Heisenberg template}.
• Whether every Heisenberg template admits an equivalent Schr\"{o}dinger template is a foundational question, and one that has persisted as an open problem.
• In the present paper we prove that for every Heisenberg template an equivalent Schr\"{o}dinger template exists.