Continuously Tunable MHz‐Range RF Magnetometry Using a Spinor Bose–Einstein Condensate

Abstract

Radio frequency (RF) magnetic field measurements in the megahertz (MHz) range are vital for modern science and engineering, with critical applications in nuclear magnetic resonance, magnetic resonance imaging, and axion dark matter detection. In this study, we demonstrate MHz RF magnetic field measurements using a sodium spinor Bose–Einstein condensate (BEC) through simultaneous multistate detection of atomic population distributions. This method enables measurements over a frequency range of 4.824–11.933 MHz, with the continuous frequency tunability through magnetic field control. This frequency range continues to represent an unexplored domain in the field of atomic RF sensing. The ultralow temperature of the BEC suppresses Doppler effects and thermal decoherence caused by atomic motion, thereby enhancing detection sensitivity of RF magnetic field. We demonstrate an interrogation‐time–normalized intrinsic sensitivity of 68.6pT/Hz$68.6\nobreakspace \mathrm{pT}/\sqrt {\mathrm{Hz}}$ at 7.903 MHz in this continuously tunable atomic RF magnetometry scheme. Looking ahead, this BEC‐based platform may be extended to exploit entangled atoms to surpass the standard quantum limit.