A non-commutative Path Space approach to stationary free Stochastic Differential Equations

Abstract

By defining tracial states on a non-commutative analogue of a path space, we construct Markov dilations for a class of conservative completely Markov semigroups on finite von Neumann algebras. This class includes all symmetric semigroups. For well chosen semigroups (for instance with generator any divergence form operator associated to a derivation valued in the coarse correspondence) those dilations give rise to stationary solutions of certain free SDEs previously considered by D. Shlyakhtenko. Among applications, we prove a non-commutative Talagrand inequality for non-microstates free entropy (relative to a subalgebra B and a completely positive map \eta:B\to B). We also use those new deformations in conjunction with Popa's deformation/rigidity techniques. For instance, combining our results with techniques of Popa-Ozawa and Peterson, we prove that the von Neumann algebra of a countable discrete group with CMAP and positive first L^2 Betti number has no Cartan subalgebras.Comment: 75 pages; new results : more resolutions of SDEs from our dilations, free Talagrand inequality generalized to relative case; (slightly) improved exposition in section 2, typos correcte