Tunable Quantum Fluctuation-Controlled Coherent Spin Dynamics

TL;DR

This paper explores a novel type of quantum spin dynamics in ultracold atoms, driven solely by zero-point quantum fluctuations, which can be precisely tuned using optical lattices and may serve as a tool to study quantum critical phenomena.

Contribution

It introduces quantum fluctuation-controlled spin dynamics (QFCSD), a new mechanism for coherent spin evolution that is highly tunable and distinct from mean-field driven dynamics.

Findings

QFCSD can be tuned by four to five orders of magnitude.

QFCSD depends uniquely on optical lattice depths and quadratic Zeeman fields.

Potential applications include calibrating quantum fluctuations and studying quantum criticality.

Abstract

Temporal evolution of a macroscopic condensate of ultra cold atoms is usually driven by mean field potentials, either due to scattering between atoms or due to coupling to external fields; and coherent quantum dynamics have been observed in various cold-atom experiments. In this article, we report results of studies of a class of quantum spin dynamics which are purely driven by zero point quantum fluctuations of spin collective coordinates. Unlike the usual mean-field coherent dynamics, quantum fluctuation-controlled spin dynamics or QFCSD studied here are very sensitive to variation of quantum fluctuations and can be tuned by four to five order of magnitude using optical lattices. They have unique dependence on optical lattice potential depths and quadratic Zeeman fields. QFCSD can be potentially used to calibrate quantum fluctuations and investigate correlated fluctuations and various universal scaling properties near quantum critical points.