Sensing Low-Frequency Field with Rydberg Atoms via Quantum Weak Measurement

TL;DR

This paper demonstrates a quantum weak measurement approach using Rydberg atoms to enhance the sensitivity of low-frequency electric field sensing, surpassing traditional methods by suppressing noise and utilizing polarization degrees of freedom.

Contribution

The work introduces a novel quantum weak measurement scheme with Rydberg atoms for low-frequency electric field detection, improving sensitivity and noise suppression over classical techniques.

Findings

Achieved a sensitivity of 33 μV/cm/Hz^1/2

Demonstrated suppression of technical noise via weak measurement

Validated the scheme's performance against theoretical models

Abstract

Recently, Rydberg atom has emerged as an attractive choice to realize quantum sensing of low-frequency electric field. The progress so far has mostly utilized the intensity and phase changes in probe laser and the corresponding detection mechanism still remains classical. Nevertheless, external field acting on the Rydberg state can induce the polarization variation of probe laser in the Rydberg electromagnetically induced transparency (EIT) system embedded in realistic multi-state atoms. We experimentally observe this phenomenon and realize signal extraction by appropriately utilizing the polarization degrees of freedom. Based on such a mechanism, we further design and implement a quantum weak measurement scheme, which clearly suppresses the technical noise and leads to considerable improvement of performance. Evaluation of the sensitivities across different post-selection angles demonstrates that the weak measurement results agree well with the theoretical model predictions. The advantages of our method are analyzed from multiple aspects, including characterizing the responses over different frequencies and comparing the responses of the weak measurement scheme and the traditional transmission-based method. After accounting for the screening effect of a measured ratio 17\% where the $^\text{87}$Rb atoms experience a substantially reduced field inside the glass cell, the performance reaches 33 $\mu\text{V}~\text{cm}^\text{-1}~\text{Hz}^\text{-1/2}$ in sensitivity and 1.0 $\mu\text{V/cm}$ in minimal detectable field for an integration time of 1000 s, as perceived by the atoms.