Elementary embeddings into ultrapower $\mathrm{II}_1$ factors without a ucp lift

Abstract

We show that there are $\mathrm{II}_1$ factors $M$ and elementary embeddings $M \to M^{\cU}$ which do not lift to sequences of UCP maps, and in fact $M$ can be chosen from any given elementary equivalence class.  Furthermore, under continuum hypothesis, we show that in the sense of cardinality ``most'' automorphisms of an ultrapower $M^{\mathcal{U}}$ of a separable $\mathrm{II}_1$ factor do not lift to a sequence of UCP maps $\varphi_n: M \to M$.