Spin-noise spectrum in a pulse-modulated field

Abstract

We measure the spin noise spectrum (SNS) of a thermal Rubidium vapor in a pulse-modulated transverse magnetic field and develop a simple theory to describe the main structure of the SNS. Notably, when the pulse area is equal to π, the SNS consists of resonances centered at half-odd-integer multiples of the modulation frequency, while revealing the spin dynamics of the system in a zero field. Our study opens a promising way of studying zero-field spin dynamics by spin noise spectrum free from any low-frequency environmental disturbances.

Raman scattering model of the spin noise

“…and low-dimensional media (e. g. [16,17]) can be addressed by SNS, but also the nuclear dynamics [18][19][20], light-matter interaction effects [21,22], spatial properties distribution [23,24], and even noise of valley redistribution of electrons [25]. Still the atomic systems attract the significant attention of researchers [26][27][28][29][30][31][32][33] as model objects which allow to reveal the fundamental pecularities of spin noise formation mechanics. In typical SNS experiments with polarimetric detection of the signal, one measures, in fact, the magnetization-noise power spectrum of the studied sample associated, in accordance with the fluctuation-dissipation theorem, with the spectrum of its magnetic susceptibility [34].…”

Zero-field spin-noise spectrum of an alkali vapor with strong spin-exchange coupling

“…This work studies the OSN spectra of a thermal state dense 87 Rb vapor in the strong SE coupling regime. We measure the noise spectra in a π-pulse-modulated (πPM) transverse magnetic field [47,48], which shifts the SN resonance out of the swamp of 1/f noises while acting like a zero-field for the SE interactions [48]. We eliminate the diffusion distortion of the spectra by expanding the probe beam over the cell's entire cross-section [49] and using an evacuated antirelaxation coated cell.…”