Dilations for operator-valued quantum measures

TL;DR

This paper establishes conditions under which countably additive operator-valued quantum measures can be dilated to projection-valued measures, extending dilation theory to Banach spaces with specific properties and measures with bounded p-variation.

Contribution

It proves that quantum measures with bounded p-variation on certain Banach spaces can be dilated to projection-valued measures, preserving countable additivity and boundedness.

Findings

Dilations exist for quantum measures on Banach spaces with Schur property or p spaces.

Introduces a p-variation norm on the dilation space.

Every measure with bounded p-variation admits a projection-valued dilation.

Abstract

This paper concerns the dilations of Banach space operator-valued quantum measures. While the recently developed general dilation theory can lead to a projection (idempotent) valued dilation for any quantum measure over the projection lattice for a von Neumann algebra that dose not contain type $I_{2}$ direct summand, such a dilation does not necessarily guarantee the preservation of countable additivity of the quantum measure. So it remain an open question whether every countably additive $B(X)$-valued quantum measure can be dilated to a countably additive projection-valued measure.The main purpose of this paper is to prove that such a dilation can be constructed if one of the following two conditions is satisfied: (i) the underling Banach space $X = \ell_{p}$ $(1\leq p < 2$) or it has Schur property, (ii) the quantum measure has bounded $p$-variation for some $ 1\leq p < \infty $. All of these were achieved by establishing a non-commutative version of a minimal dilation theory on the so-called elementary dilation space equipping with an appropriate dilation norm. In particular, the newly introduced $p$-variation norm on the elementary dilation space allows us to prove that every operator-valued quantum measure with bounded $p$-variation has a projection-valued quantum measure dilation that preserves the boundedness of the $p$-variation.