arXiv subjects

Xiayang Fan

Publications and source records attributed to Xiayang Fan.

4 recordsLinked to original sources

arXiv2026

Quantum sensing of low-frequency electric signal enabled by modulated auxiliary field in Rydberg atoms

Rydberg atoms have emerged as a versatile and efficient platform for high-sensitivity quantum sensing of free-space electric fields, with remarkable progress in detecting low-frequency signals. To date, low-frequency Rydberg receivers have relied on a constant bias field, typically realized via intra-cell electrodes or Rydberg plasmas generated by photoelectric effects or inter-atomic interactions. While these approaches improve sensitivity, they suffer from inherent challenges in calibration, long-term stability, and robustness, hindering practical deployment. Here, we propose, design, and experimentally demonstrate a quantum sensing scheme for low-frequency electric signals using modulated auxiliary fields in Rydberg atoms. Unlike conventional methods that employ external DC electric fields that are often fully shielded by adsorbed atom layers on the cell walls, we introduce an AC-field modulation strategy. The incoming low-frequency signal mixes with the auxiliary field, and together they induce Stark shifts of the Rydberg level. These shifts are mapped onto the probe laser via electromagnetically induced transparency (EIT), in a manner analogous to heterodyne detection. We demonstrate a sensitivity of $7.5 \pm 2.6~\mathrm{\mu V/(cm\cdot Hz^{1/2})}$ at 5 kHz and a minimal detectable field of $0.26 \pm 0.04~\mathrm{\mu V/cm}$ with an integration time of 1000 s. Furthermore, we extend this approach to systematically analyze the performance of generalized auxiliary fields containing multiple frequency components. By virtue of modulated auxiliary field and quantum frequency mixing, our results establish a robust and systematic framework for quantum sensing of low-frequency electric fields with Rydberg atoms, offering improved sensitivity, stability, and immunity to environmental drifts.

quant-ph↗

arXiv2026

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

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.

physics.atom-ph↗

arXiv2025

Heterodyne detection of low-frequency fields via Rydberg EIT with phase demodulation

Recently, the rapid progress of quantum sensing research reveals that the Rydberg atoms have great potentials in becoming high-precision centimeter-scale antenna of low-frequency fields. In order to facilitate efficient and reliable detection of low-frequency fields via Rydberg atoms, we design, implement and analyze a special but low-cost and scalable method based on heterodyning processes under the condition of electromagnetically induced transparency (EIT) embedded in typical two-photon ground-Rydberg transition. Instead of relying on observing changes in absorption of light by Rydberg atoms, our method focuses on the phase modulation effect on the probe laser induced by the low-frequency fields via the Rydberg EIT mechanism and utilizes a demodulation process to accurately retrieve the signal. The general principles of our method apply to both electric and magnetic fields and it is even possible to realize the combination of both functionalities in the same apparatus. In particular, we experimentally demonstrate the full cycle of operations with respect to both cases. In the measurement of low-frequency electric fields, we discover that the Rydberg dipole-dipole interaction among atoms induce linear superposition of Rydberg states with different angular momentum that generates a first-order response corresponding to the signature of linear Stark effect. As the Rydberg atoms have excellent coupling strengths with electric fields, our results indicate that our method can hopefully reach high-precision performance for practical tasks in the future.

physics.atom-ph↗

arXiv2024

Fast entangling quantum gates with almost-resonant modulated driving

Recently, the method of off-resonant modulated driving (ORMD) with a special category of synthetic analytical pulses has improved the experimental performance of two- and multi-qubit gates and aroused many interests for further investigations. It particularly offers a helpful tool to the cold atom qubit platform and works well with the Rydberg dipole-dipole interaction. In order to explore more possibilities and wider ranges of options in constructing fast-speed and high-fidelity quantum logic gates, we design and analyze the entangling quantum gates via the almost-resonant modulated driving (ARMD) method. Apart from the apparent distinctions in resonance conditions, the ARMD gate protocols also have its different mechanisms in quantum physics compared with ORMD gate protocols. ARMD gates usually have abrupt phase changes and at certain points during the time evolution. In other words, whilst the modulation forms the key concept of high-fidelity Rydberg blockade gates, the on-off resonance condition can lead to nontrivial nuances in the styles of dynamics. From a more fundamental point of view, the ORMD and the ARMD methods all together belong to the unitary operation family of fast modulated driving with respect to precisely characterized inter-qubit interactions, which usually allows the quantum logic gate to concludes within one continuous pulse.

quant-ph↗