Levitated Ferromagnetic Magnetometer with Energy Resolution Well Below ℏ

Area of Science:

• Quantum sensing
• Condensed matter physics
• Fundamental science

Background:

• A quantum limit (E_{R}≳ℏ) constrains magnetic field measurement resolution.
• Existing quantum magnetometers like SQUIDs and atomic magnetometers adhere to this limit.
• Highly correlated spin systems, such as spinor BECs, can surpass this established limit.

Purpose of the Study:

• To investigate a novel method for surpassing the quantum limit in magnetic field measurements.
• To demonstrate superior energy resolution using a levitated ferromagnet system.
• To explore potential applications in condensed matter, biophysics, and dark matter searches.

Main Methods:

• Utilizing a hard ferromagnet levitated above a superconductor at cryogenic temperatures.
• Implementing quantum measurement techniques to achieve high energy resolution.
• Proposing an experimental setup for axionlike dark matter detection.

Main Results:

• Achieved an energy resolution of E_{R}=(0.064±0.010) ℏ, significantly below the quantum limit.
• Demonstrated a system capable of surpassing the performance of conventional quantum magnetometers.
• Projected potential for achieving E_{R}<10^{-3} ℏ with future improvements.

Conclusions:

• The levitated ferromagnet system offers a pathway to overcome the established quantum limit for magnetic field measurements.
• This technology holds promise for transformative applications across diverse scientific fields.
• The proposed dark matter search experiment could achieve unprecedented sensitivity.