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Rydberg quantum sensors
The most common sensing application for Rydberg atoms is to measure electric fields. Compared to traditional dipole antenna sensors, atoms are self-calibrating, minimally perturbative (without metal parts), and maintain near-constant sensitivity across a wide bandwidth (from DC to THz). In this context, mutual interactions between atoms, which are essential in quantum optics and quantum information processing, becomes a limitation. We are interested in exploring the role of atomic interactions in typical sensing scenarios, aiming to mitigate their negative effects and potentially repurpose them to enhance sensing. At the same time, we are broadly examining sensing contexts to identify opportunities where different forms of atomic interactions may be useful.
Nonlinear optical spectra from Rydberg-mediated photon-photon interactions
Nonlinear optical spectra from Rydberg-mediated photon-photon interactions
Our work addresses a pivotal question at the intersection of nonlinear optics, quantum optics, quantum sensing, cold atoms and many-body Rydberg physics: how do many-body interactions affect (microwave-dressed) Rydberg electromagnetically induced transparency (EIT)? This question sits in a challenging theoretical regime where traditional approaches struggle. Fully quantized field theory works well for one or two photons but becomes intractable in the many-body regime, while conventional mean-field approaches break down for strongly interacting Rydberg systems. Despite the importance in terms of fundamental Rydberg physics and practical significance for quantum sensing, experimental evidence remains surprisingly scarce, and existing theoretical models yield widely divergent predictions.
We experimentally investigate Rydberg interaction-induced nonlinearity in cold-atom EIT. In a three-level EIT system, increasing photon-photon interactions produces nonlinear spectral broadening accompanied by resonance shifts, while a microwave-dressed four-level system exhibits pronounced nonlinear broadening without detectable spectral shifts. Our three-level data can be explained by a conditional superatom model, whereas our four-level observations are surprisingly captured by a simple dephasing model. Comparisons with three representative models provide key insights to the role of many-body interactions in Rydberg EIT spectroscopy. Furthermore, our results clarify the conditions under which microwave field characterization can be performed in the nonlinear regime without introducing systematic bias.
Ref: Xinghan Wang, Yupeng Wang, Aishik Panja, Qi-Yu Liang, “Nonlinear optical spectra from Rydberg-mediated photon-photon interactions”, arXiv:2602.11563
Robust Rydberg facilitation via rapid adiabatic passage
Robust Rydberg facilitation via rapid adiabatic passage
While the Rydberg blockade mechanism has enabled high-fidelity quantum operations, its complementary antiblockade (facilitation) regime opens an entirely new class of kinetically constrained dynamics, giving rise to novel quantum phases and thermalization phenomena unattainable under blockade. Beyond quantum simulation, it also provides new opportunities for quantum information processing, enabling faster gate protocols and native SWAP operations. However, a central roadblock has persisted: the sensitivity of antiblockade to experimental imperfections, particularly position disorder in atomic arrays, which has severely limited experimental progress and achievable fidelities.
We introduce a disorder-immune implementation of Rydberg facilitated excitation that remains insensitive to atomic position disorder and laser parameter variations, achieving robustness under realistic experimental conditions. Numerically demonstrated high-gain avalanche excitation growth in 1D and 2D arrays, establishing a pathway to low-dark-count, single-photon-level sensing and rare-event detection.
Ref: Xinghan Wang, Yupeng Wang, Qi-Yu Liang, “Robust Rydberg facilitation via rapid adiabatic passage”, Phys. Rev. Research 8, 013154 (2026)
Electric field control for experiments with atoms in Rydberg states
Electric field control for experiments with atoms in Rydberg states
We developed a novel, simple, and highly compact electrode assembly design that allows us to fully control the electric field in the vicinity of the atoms without restricting high NA optical access. We achieve instantaneous stray electric field cancellation to better than 10 mV/cm, with drifts of no more than 20 mV/cm over a few hours and 50 mV/cm day-to-day. This level of electric control is essential for atoms excited to high n or high angular momentum l Rydberg states. Our design can be implemented in almost any glass cell with little to no modifications.
Ref: Aishik Panja, Yupeng Wang, Xinghan Wang, Junjie Wang, Sarthak Subhankar, and Qi-Yu Liang, "Electric field control for experiments with atoms in Rydberg states", AIP Advances 14, 125013 (2024). Chosen as an Editor's Pick
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