$\Phi^4_3$ Theory from many-body quantum Gibbs states

TL;DR

This paper rigorously derives the three-dimensional $\

Contribution

It introduces a novel semiclassical limit approach connecting quantum Bose gases to the $\

Findings

Established a rigorous link between quantum Gibbs states and $\

Developed new paracontrolled calculus techniques for nonlocal interactions

Connected quantum many-body problems with classical stochastic measures

Abstract

We derive the $\Phi^4_3$ measure on the torus as a rigorous limit of the quantum Gibbs state of an interacting Bose gas. To be precise, starting from many-body quantum mechanics, where the problem is linear and regular but involving non commutative operators, we justify the emergence of the $\Phi^4_3$ measure as a semiclassical limit which captures the formation of Bose--Einstein condensation just above the critical temperature. We employ and develop several tools from both stochastic quantization and many-body quantum mechanics. Since the quantum problem is typically formulated using a nonlocal interaction potential, our first key step involves approximating the $\Phi^4_3$ measure through a Hartree measure with nonlocal interaction, achieved by developing new techniques in paracontrolled calculus. The connection between the quantum problem and the Hartree measure emerges through a variational interplay between classical and quantum models.