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Non-linear amplification of small spin precession using long range dipolar interactions

M. P. Ledbetter·I. M. Savukov·M. V. Romalis
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Abstract

In measurements of small signals using spin precession the precession angle usually grows linearly in time. We show that non-linear interactions between particles can lead to an exponentially growing spin precession angle, resulting in an amplification of small signals and raising them above the noise level of a detection system. We demonstrate amplification by a factor of greater than 8 of a spin precession signal due to a small magnetic field gradient in a spherical cell filled with hyperpolarized liquid $^{129}$Xe. This technique can improve the sensitivity in many measurements that are limited by the noise of the detection system, rather then the fundamental spin-projection noise.

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M. P. Ledbetter, I. M. Savukov, M. V. Romalis. 2005-03-31. Non-linear amplification of small spin precession using long range dipolar interactions. https://doi.org/10.1103/physrevlett.94.060801

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