Duration of Classicality of Homogeneous Condensates with Attractive Interactions

TL;DR

This paper investigates how long homogeneous condensates with attractive interactions remain well-described by classical equations before quantum effects cause significant depletion, impacting models of dark matter and bosonic fluids.

Contribution

It provides a quantitative estimate of the duration of classicality for homogeneous condensates with attractive interactions, considering both contact and gravitational cases.

Findings

Classical description persists until quantum depletion occurs.

Quantum parametric resonance causes pair production out of the condensate.

Estimated time scales for condensate depletion are provided.

Abstract

Dark matter axions and other highly degenerate bosonic fluids are commonly described by classical field equations. In a recent paper \cite{BECprop} we calculated the duration of classicality of homogeneous condensates with attractive contact interactions and of self-gravitating homogeneous condensates in critical expansion. According to their classical equations of motion, such condensates persist forever. In their quantum evolution parametric resonance causes quanta to jump in pairs out of the condensate into all modes with wavevector less than some critical value. We estimated in each case the time scale over which the condensate is depleted and after which a classical description is invalid.