Nuclear-Spin Comagnetometer Based on a Liquid of Identical Molecules

Area of Science:

• Atomic physics
• Precision measurements
• Fundamental interactions

Background:

• Atomic comagnetometers are crucial for detecting anomalous spin-dependent interactions.
• Magnetic field gradients represent a significant source of systematic error in these experiments.
• Existing comagnetometers often use overlapping ensembles of different molecules, limiting precision.

Purpose of the Study:

• To develop a comagnetometer design that minimizes systematic errors caused by magnetic field gradients.
• To enhance the sensitivity of searches for hypothetical spin-dependent gravitational interactions.
• To improve constraints on the spin-gravity coupling of nucleons.

Main Methods:

• Utilized a comagnetometer based on the nuclear spins within an ensemble of identical molecules (single-species approach).
• Measured the spin-precession frequency ratio to assess sensitivity to magnetic field gradients.
• Compared performance against comagnetometers using overlapping ensembles of different molecules.

Main Results:

• The single-species comagnetometer demonstrated a suppression of first-order magnetic field gradient dependence by over an order of magnitude.
• Achieved sensitivity to hypothetical spin-dependent gravitational energy of nuclei at the 10^-17 eV level.
• Results are comparable to the most stringent existing experimental constraints.

Conclusions:

• The single-species atomic comagnetometer significantly mitigates magnetic field gradient systematic errors.
• This method offers a promising pathway for improving constraints on spin-gravity coupling by several orders of magnitude.
• Potential for enhanced sensitivity when combined with signal-boosting techniques like parahydrogen-induced polarization.