Criticality-enhanced quantum sensing in ferromagnetic Bose-Einstein condensates: role of readout measurement and detection noise

TL;DR

This paper theoretically demonstrates that ferromagnetic Bose-Einstein condensates can achieve sensitivity beyond the standard quantum limit near critical points, even with experimental imperfections like temperature and detection noise.

Contribution

It reveals the potential for sub-SQL quantum sensing in ferromagnetic condensates by analyzing Fisher information and the effects of measurement noise and temperature.

Findings

Beyond-SQL scaling near critical points

Depletion and transverse magnetization as effective signals

Feasibility of sub-SQL sensing with current technology

Abstract

We theoretically investigate estimation of the control parameter in a ferromagnetic Bose-Einstein condensate near second order quantum phase transitions. We quantify sensitivity by quantum and classical Fisher information and using the error-propagation formula. For these different metrics, we find the same, beyond-standard-quantum-limit (SQL) scaling with atom number near critical points, and SQL scaling away from critical points. We find that both depletion of the $m_f=0$ Zeeman sub-level and transverse magnetization provide signals of sufficient quality to saturate the sensitivity scaling. To explore the effect of experimental imperfections, we study the scaling around criticality at nonzero temperature and with nonzero detection noise. Our results suggest the feasibility of sub-SQL sensing in ferromagnetic condensates with current experimental capabilities.