Compact quantum metric spaces from free probability

David Jekel; Therese Basa Landry

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arXiv · 2606.19578

Compact quantum metric spaces from free probability

David Jekel·Therese Basa Landry

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Abstract

We study quantum metric space structures on operator algebras arising from free probability, namely those associated to $q$-Gaussians and free Gibbs laws for convex potentials. We note that even for free semicirculars, Voiculescu's dual system does not produce a quantum metric space structure that recovers the weak-$*$ topology on the state space. However, for $q$-Gaussians, we can define a compact quantum metric space using length-like functions by the same method as has already been used for hyperbolic groups, quantum groups of rapid decay, free products, and free graph algebras. Next, motivated by the free transport results for free Gibbs laws, we describe a universal way of defining Lip-norms in terms of a generating set, which behaves well under changes of coordinates. We show using semigroup regularization that this Lip-norm defines a quantum metric space structure for $q$-Gaussians, and then transfer this property to free Gibbs laws for convex potentials using free transport.

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David Jekel, Therese Basa Landry. 2026-06-17. Compact quantum metric spaces from free probability. https://arxiv.org/abs/2606.19578

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