Abstract
Spin noise spectroscopy is emerging as a powerful technique for studying the dynamics of various spin systems also beyond their thermal equilibrium and linear response. Here, we study spin fluctuations of room-temperature neutral atoms in a Bell-Bloom type magnetometer. Driven by indirect pumping and undergoing a parametric excitation, this system is known to produce noise-squeezing. Our measurements not only reveal a strong asymmetry in the noise distribution of the atomic signal quadratures at the magnetic resonance, but also provide insight into the mechanism behind its generation and evolution. In particular, a structure in the spectrum is identified which allows to investigate the main dependencies and the characteristic timescales of the noise process. The results obtained are compatible with parametrically induced noise squeezing. Notably, the noise spectrum provides information on the spin dynamics even in regimes where the macroscopic atomic coherence is lost, effectively enhancing the sensitivity of the measurements. Our work promotes spin noise spectroscopy as a versatile technique for the study of noise squeezing in a wide range of spin based magnetic sensors.
Highlights
In standard spin-noise spectroscopy (SNS), spontaneous fluctuations of the atomic spins in thermodynamic equilibrium can provide information on the system properties, such as resonance frequencies and rates of the decoherence processes [1,2,3,4,5,6,7,8]
We demonstrate a nonstandard mode of the spin-noise analysis applied to an out-of-equilibrium nonlinear atomic system realized by a Bell-Bloom atomic magnetometer
Thermal atomic vapors create a platform for a wide range of precise atomic sensors with performances often limited by atomic projection noise [32]
Summary
In standard spin-noise spectroscopy (SNS), spontaneous fluctuations of the atomic spins in thermodynamic equilibrium can provide information on the system properties, such as resonance frequencies and rates of the decoherence processes [1,2,3,4,5,6,7,8]. First attempts to explore SNS beyond the regimes of thermodynamic equilibrium [11,12,13] and linear response have appeared [14,15,16] This is of interest as, for example, standard spin-noise spectra cannot typically disclose information on the system’s response to resonant driving fields (out-of-equilibrium dynamics) or reveal the (linear and nonlinear) couplings between the spin coherences associated with the system’s relevant energy levels [14]. We test this nonconventional SNS on an atomic spin ensemble exposed to a Bell-Bloom type excitation [17,18] This system undergoes pumping, via optical excitation, and spin-exchange collisions, and, an ensemble polarization is created which precesses around an external magnetic field.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
