Enhancement of spin noise spectroscopy of rubidium atomic ensemble by using of the polarization squeezed light

Abstract

We measured the spin noise spectroscopy (SNS) of rubidium atomic ensemble with two different atomic vapor cells (filled with the buffer gases or coated with paraffin film on the inner wall), and demonstrated the enhancement of signal-to-noise ratio (SNR) by using of the polarization squeezed state (PSS) of 795-nm light field with Stokes operator Λ S 2 squeezed. PSS is prepared by locking the relative phase between the squeezed vacuum state of light obtained by a sub-threshold optical parametric oscillator and the orthogonal polarized local oscillator beam by means of the quantum noise lock. Under the same conditions, PSS can be employed not only to improve SNR, but also to keep the full width at half maximum (FWHM) of SNS unchanged, compared with the case of using polarization coherent state (PCS), and the enhancement of SNR is positively correlated with the squeezing level of PSS. With the increase of probe laser's power and atomic number density, the SNR and FWHM of SNS will increase correspondingly. With the help of PSS of Stokes operator Λ S 2 , quantum enhancement of both SNR and FWHM of SNS signal has been demonstrated by controlling optical power of the Λ S 2 polarization squeezed light beam or atomic number density in our experiments.

Isolating noise and amplifying signal with quantum Cheshire cat

“…A significant concern in experiments is the minimizing noise in the relevant signal and designing measurement techniques that achieve the same. A measurement strategy with a greater signal to noise ratio is typically favored by experimentalists [28][29][30][31][32][33], apart from logistics and dependencies on other constraints imposed by the particular scenario. We consider a situation in which noise may be introduced during the process of weak value amplification if the Hamiltonian in Eq.…”