Chip-Scale Ultra-Low Field Atomic Magnetometer Based on Coherent Population Trapping

Area of Science:

• Atomic physics
• Quantum sensing
• Miniaturized devices

Background:

• Atomic magnetometers are crucial for measuring magnetic fields.
• Coherent population trapping (CPT) is a sensitive atomic spectroscopy technique.
• Miniaturized CPT magnetometers typically require finite magnetic fields for operation.

Purpose of the Study:

• To develop a chip-scale atomic magnetometer operating near zero magnetic field.
• To exploit asymmetric population in cesium hyperfine ground states for magnetic field sensitivity.
• To demonstrate a miniaturized magnetometer suitable for low magnetic field environments.

Main Methods:

• Utilizing coherent population trapping in a chip-scale device (0.94 cm³).
• Exploiting asymmetric population among magnetic sublevels in cesium's hyperfine ground state.
• Observing resonance signals sensitive to magnetic fields despite degeneracy.

Main Results:

• Achieved magnetic field discrimination using a dispersive signal near zero and finite fields (tens of micro-tesla).
• Demonstrated operation in low magnetic field environments previously inaccessible to miniaturized CPT magnetometers.
• Measured a noise floor of 300 pT/Hz^1/2 at zero-field, comparable to conventional finite-field measurements.

Conclusions:

• The developed chip-scale atomic magnetometer operates effectively near zero magnetic fields.
• The device is suitable for low magnetic field applications, overcoming previous limitations of miniaturized CPT magnetometers.
• This work paves the way for integrated atomic magnetometers with a broad operating range.