G. Kevrekidis'
- 'C. Ticknor'
title: 'Enhanced quantum spin fluctuations in a binary Bose-Einstein condensate'
---

Introduction
============

Quantum fluctuations are ubiquitous in nature, lying at the heart of a wide variety of physical phenomena ranging from, for example, the Van der Waals force and the Casimir effect, through to Hawking radiation of black holes and the theory of cosmic inflation, providing the initial seed for the large-scale structure of the universe today. Despite their importance, quantum fluctuations are notoriously difficult to describe theoretically and many important questions remain unanswered [@SachdevBook; @Pitaevskii16].

Focusing on quantum fluids with short-range interactions, the role of quantum fluctuations becomes important in several qualitatively distinct regimes. Among the most dramatic of these are the one-dimensional systems, for which quantum fluctuations are so large that long-range order is destroyed [@Mermin1966; @Hohenberg1967]. Another well-known regime is that of high density (and strong interactions) where, for example, in the superfluid phase of liquid $^{4}$He, quantum fluctuations cause a depletion of the underlying Bose-Einstein condensate (BEC) of around 90% [@Dalfovo1999].

Dilute quantum gases have accelerated quantum-fluctuation research in recent years, offering a clean and highly-controllable testbed in which nearly all aspects are tunable, such as the interaction strength, confinement, 